A method for calculating the concentration of molten steel mixed in a continuous casting tundish

Abstract

The application discloses a continuous casting tundish molten steel mixing concentration calculation method, and is characterized by comprising the following steps: S1: using an iterative calculation method to calculate the current time solute mixing degree; S2: comparing the calculated current time solute mixing degree with a standard value, if the comparison is correct, it is determined that the molten steel entering the continuous casting machine at the time meets the requirements; if the comparison is incorrect, step S1 is repeated again. The application has the advantages that the method can predict the chemical composition of each position of the mixed pouring billet through a mathematical model, position the mixed pouring billet, optimize the flame cutting parameters, and improve the qualified continuous casting billet yield. The method can obtain the ladle pouring information, including time, composition, and the like, obtain the actual detected composition, calculate the chemical composition mixing degree range of the mixed pouring heats through a mathematical model, and calculate the chemical composition mixing degree of each position in real time, so that the reasonable cutting position is determined, and thus the chemical composition of the mixed pouring billet and the upper and lower continuous casting billets can meet the design requirements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal materials, and particularly relates to a continuous casting tundish molten steel mixing concentration calculation method. BACKGROUND

[0002] In view of the increasingly competitive steel market, the production mode presents the characteristics of small batch, multi-variety and multi-specification, and the continuous casting tundish molten steel mixing concentration calculation model and the slab steel grade division method can well meet the above requirements, while ensuring the production continuity and stability, significantly improving the production efficiency and reducing the cost, effectively enhancing the market competitiveness, creating considerable economic benefits for enterprises, and the multi-furnace continuous casting of different steel grades is carried out on the same casting tundish, due to the difference in steel grade composition, mixed casting blanks are inevitably produced, for enterprises, it is required to shorten the mixed casting time to the maximum extent and reduce the length of the mixed casting blanks to be judged as waste, in order to optimize the mixed casting process to minimize the length of the mixed casting blanks, it is of great significance to accurately predict the starting position and composition change of the mixed casting blanks in the continuous casting process of different steel grades. SUMMARY

[0003] The application aims to provide a continuous casting tundish molten steel mixing concentration calculation method to predict the starting position and composition change of the mixed casting blanks in the continuous casting process of different steel grades, which is suitable for a single flow slab continuous casting machine.

[0004] The application is implemented by the following technical scheme: a continuous casting tundish molten steel mixing concentration calculation method, characterized by comprising the following steps:

[0005] S1: the solute mixing degree at the current time is iteratively calculated by using the following formula:

[0006] ;

[0007] Wherein, R1 is the solute mixing degree of the current period, and R0 is the solute mixing degree of the previous period;

[0008] Wherein, D lw is the weight of the molten steel flowing from the ladle into the tundish, and the value is obtained by the following formula:

[0009] ;

[0010] In the formula, L w1 is the weight of the ladle in the current period, and L w0 is the weight of the ladle in the previous period;

[0011] In the formula, D m is the weight of the molten steel flowing into the crystallizer, and the value is obtained by the following formula;

[0012] ;

[0013] wherein D tw is the change in tundish liquid steel weight, the value of which is obtained by the following formula:

[0014] ;

[0015] wherein: T w1 is the current tundish weight, T w0 is the previous tundish weight;

[0016] S2: comparing R1 with the standard value, if it is consistent, it is determined that the liquid steel entering the continuous casting machine at this moment meets the requirements; if it is not consistent, step S1 is repeated again.

[0017] Further: in the step S2, the following steps are included:

[0018] S2.1: determining the solute mixing degree range of the continuous casting steel grade

[0019] For a specified chemical composition, the solute mixing degree range is calculated respectively, and E is the element symbol;

[0020] Let the previous steel grade be S0, and the current mixed casting steel grade be S1; for the mixed casting element E, each steel grade has its own chemical composition range, and each chemical composition range is divided into an upper limit E u , a lower limit E d , and a standard value E s ;

[0021] The following calculation formula is used to determine the maximum solute mixing degree of the E element of the previous liquid steel:

[0022] ;

[0023] R E0 is the upper limit value of the chemical element solute mixing degree of the previous liquid steel;

[0024] E u0 is the upper limit value of the chemical composition of the previous liquid steel;

[0025] E s0 is the standard value of the chemical composition of the previous liquid steel;

[0026] E S1 is the standard value of the chemical composition of the current liquid steel;

[0027] The following calculation formula is used to determine the minimum solute mixing degree of the E element of the current liquid steel:

[0028] ;

[0029] R E1 is the lower limit value of the chemical element solute mixing degree of the current liquid steel;

[0030] E d1 is the lower limit value of the chemical composition of the current molten steel in the furnace;

[0031] S2.2: compare R1 with the standard value R E0 and R E1 , if R1∈[R E0 , R E1 , it is qualified; otherwise, it is unqualified.

[0032] Further, in the step S2, the following steps are included:

[0033] S2.1: determine the range of each element in the tundish:

[0034] According to the value of R1 and the content of each element in the initial ladle and tundish, the content of each element in the current tundish is calculated;

[0035] S2.2: compare the content range of the specified chemical composition with the corresponding element content in S2.1, if they all meet the range requirement, it is qualified; otherwise, it is unqualified.

[0036] Further, if it is determined to be qualified in S2, the molten steel entering the continuous casting machine at the current time corresponds to the steel plate that meets the requirements, and the steel plate can be cut at the corresponding position. The cut steel plate is a qualified steel plate.

[0037] Further, the period is 5s.

[0038] The advantages of the present application are: predicting the starting position and composition change of mixed billets in different steel grade continuous casting process, suitable for single flow slab continuous casting machine, when the composition difference of continuous casting furnace is large, the composition of mixed billets cannot be accurately judged, the method predicts the chemical composition of each position of mixed billets through mathematical model, positions the mixed billets, optimizes the flame cutting parameters, improves the qualified continuous casting billet yield, the method obtains the opening information of the ladle, including time, composition, etc., obtains the actual test composition, calculates the chemical composition mixing degree range of the mixed furnace through the mathematical model, and calculates the chemical composition mixing degree of each position in real time, determines the reasonable cutting position, so as to ensure that the chemical composition of the upper and lower continuous casting billets of the mixed billet meets the design requirements, and has good application prospect in the field of single flow slab continuous casting machine. The method can shorten and reduce the length of the mixed billet to be discarded, optimize the mixed casting process to minimize the length of the mixed billet, accurately predict the starting position and composition change of mixed billets in the mixed casting process of different steel grades, etc. DETAILED DESCRIPTION

[0039] The application discloses a continuous casting tundish molten steel mixing concentration calculation method, which comprises the following steps:

[0040] S1: iteratively calculate the solute mixing degree at the current time by using the following formula:

[0041] ;

[0042] Wherein, R1 is the current cycle solute mixing degree, R0 is the previous cycle solute mixing degree;

[0043] Wherein, D lw is the tundish inflow molten steel weight, the value of which is obtained by the following formula:

[0044] ;

[0045] In the formula: L w1 is the current cycle tundish weight, L w0 is the previous cycle tundish weight;

[0046] In the formula, Dm is the inflow crystallizer molten steel weight, the value of which is obtained by the following formula:

[0047] ;

[0048] Wherein, D tw is the tundish molten steel weight change, the value of which is obtained by the following formula:

[0049] ;

[0050] In the formula: T w1 is the current time tundish weight, T w0 is the previous cycle tundish weight;

[0051] S2: Compare R1 with the standard value, if it is consistent, it is determined that the molten steel entering the continuous casting machine at this time meets the requirements; if it is not consistent, repeat step S1 again.

[0052] Preferred: namely the first determination mode: in the step S2, the following steps are included:

[0053] S2.1: determine the continuous casting steel solute mixing degree range required for production, that is, when the replaced steel reaches the qualified condition, the required continuous casting steel solute mixing degree range is taken as the standard value, so as to compare R1 with the standard value and determine whether it meets the requirements; the specific steps are as follows:

[0054] For a specified chemical composition (there are many components in the new steel grade, which can be aimed at the main components or each component respectively), the solute mixing degree range is calculated respectively, and E is the element symbol;

[0055] Let the previous steel grade be S0, and the current mixed casting steel grade be S1 (in the following formula, the subscript after 0 is the parameter of the previous furnace, and the subscript after 1 is the parameter of the current furnace); for each mixed casting element E, each steel grade has a respective chemical composition range, and each chemical composition range is divided into an upper limit E u , a lower limit E d , and a standard value E s .

[0056] The calculation rule of the element mixing degree range is as follows, taking E d1 > E u0 as an example (usually of this type, E d1 is less than E u0 , and the same applies, which will not be repeated here), that is, the current furnace element range is greater than the previous furnace element range.

[0057] The following calculation formula is used to determine the maximum solute mixing degree of E element in the previous furnace molten steel:

[0058] ;

[0059] R E0 is the upper limit value of the chemical element solute mixing degree of the previous furnace molten steel;

[0060] The following calculation formula is used to determine the minimum solute mixing degree of E element in the current furnace molten steel:

[0061] ;

[0062] R E1 is the lower limit value of the chemical element solute mixing degree of the current furnace molten steel;

[0063] E d1 is the lower limit value of the chemical composition of the current furnace molten steel;

[0064] S2.2 compares R1 with the standard values R E0 and R E1 . If R1 ∈ [R E0 , R E1 ], it is in conformity; otherwise, it is not in conformity.

[0065] Preferably: that is, the second determination method: in the step S2, the following steps are included:

[0066] S2.1: determining the range of each element in the tundish:

[0067] According to the value of R1 and the content of each element in the ladle and the tundish, the content of each element in the current tundish is calculated;

[0068] S2.2: Compare the content range of the specified chemical composition with the content of the corresponding element in S2.1. If both meet the range requirements, it is qualified; otherwise, it is not qualified.

[0069] Preferably, if it is determined to be qualified in S2, the steel plate corresponding to the molten steel entering the continuous casting machine at the current time is a qualified steel grade. According to the distance from the outlet to the cutting point and the pulling speed, the lag time is determined, and the steel plate is cut at the corresponding time (obtained by dividing the distance from the outlet to the cutting point by the pulling speed). The cut steel plate is a steel plate that meets the requirements of the new steel grade.

[0070] Preferably, the period of iterative calculation is 5s.

[0071] The present scheme aims to solve the problem in the prior art that when the composition difference of continuous casting is large, the composition of mixed casting billet cannot be accurately judged. The method optimizes the flame cutting parameters and improves the qualified continuous casting billet yield by predicting the chemical composition of each position of the mixed casting billet through a mathematical model and positioning the mixed casting billet. The method acquires the tundish opening information including time, composition, etc., acquires the actual detected composition, calculates the chemical composition mixing degree range of the mixed furnace through a mathematical model, and calculates the chemical composition mixing degree of each position in real time to determine a reasonable cutting position, thereby ensuring that the chemical composition of the upper and lower continuous casting billets of the mixed casting billet meets the design requirements. The method effectively solves the problems of large mixed casting loss and unreasonable production sequence of different composition steel grades. Through verification, the method can accurately judge the positions of the mixed casting billet and the normal billet, accurately predict the starting position, end position and composition change of the mixed casting billet, and provide effective measures for optimizing the process of mixed casting of different steel grades in the continuous casting process to reduce the length of the mixed casting billet.

[0072] The present application is further described below through specific examples. Examples

[0073] A method for calculating the mixing concentration of molten steel in a continuous casting tundish, the specific steps and parameters are as follows:

[0074] (1) In the process of continuous casting of different steel grades, the tundish needs to be replaced. The molten steel flows out of the tundish into the tundish and mixes with the molten steel of the previous furnace. The mixing of the molten steel in the tundish is related to the flow control device in the tundish and the continuous casting conditions. After the mixed molten steel leaves the tundish, it enters the crystallizer. The element diffusion in the solidification process is ignored, and only the mixing process of the molten steel is considered.

[0075] (2) According to the weight reduction of the ladle in one calculation period, the change of the tundish, the solute mixing degree coefficient obtained in the previous calculation period, the solute mixing degree in the current time is iteratively calculated:

[0076] Let the model calculation period be Dt (5s); the weight of the ladle in the previous period is L w0 , and the weight of the ladle in the current period is L w1, the ladle weight in the previous cycle is T w0 , the tundish weight at the current time is T w1 , the solute mixing degree coefficient is R, R∈[0, 1], the solute mixing degree in the previous cycle is R0, and the solute mixing degree in the current cycle is R1;

[0077] Therefore, the steel weight flowing into the tundish from the ladle is

[0078] ;

[0079] The tundish steel weight change

[0080] ;

[0081] From the ladle steel weight change and the tundish steel weight change, the steel weight flowing into the crystallizer can be derived;

[0082] ;

[0083] The following iterative calculation formula is used for iterative calculation of the solute mixing degree:

[0084] ;

[0085] Initial condition: reset R0=0 at the ladle opening time;

[0086] (3) Determine the solute mixing degree range of continuous casting steel. For a specified chemical composition, such as C, Si, Mn, S, P, etc., the solute mixing degree range is calculated respectively, and E is taken as the element symbol here;

[0087] Let the previous furnace steel be S0, and the current mixed casting steel be S1; for mixed casting element E, each steel has its own chemical composition range, and each chemical composition range is divided into upper limit E u , lower limit E d , and standard value E s ;

[0088] The calculation element mixing degree range rule is as follows, taking E d1 >E u0 as an example, that is, the current furnace element range is greater than the previous furnace element range;

[0089] The following calculation formula is used to determine the maximum solute mixing degree of E element of the previous furnace steel:

[0090] ;

[0091] R E0 : the upper limit value of the chemical element solute mixing degree of the previous furnace steel;

[0092] The minimum solute mixing degree of E element of the current furnace molten steel is determined by using the following calculation formula:

[0093] ;

[0094] R E1 : is the lower limit value of the chemical element solute mixing degree of the current furnace molten steel;

[0095] (3) Through the above iteration formula and the definition range of chemical elements, it is found that the solute mixing degree corresponding to the qualified standard of each element in the post-furnace molten steel is different, and the mixing standard of different elements is that the solute mixing degree meets the solute mixing degree corresponding to the element of the post-furnace molten steel. The solute mixing degree corresponding to the mixing depends on the chemical composition definition range of the pre-furnace molten steel and the post-furnace molten steel. The standard for complete mixing is that the solute mixing degree of all elements meets the solute mixing degree corresponding to the new steel grade. When the composition of the new furnace is higher than that of the pre-furnace, it is beneficial to rapid mixing to control the composition of the new furnace according to the upper limit, and when the composition of the new furnace is lower than that of the pre-furnace, it is beneficial to accelerate mixing to control the composition of the new furnace according to the lower limit. Real-time tracking of the casting speed and the casting section, according to the solute mixing degree calculation formula, the composition content of each element of the mixed casting billet at different positions along the casting direction is calculated to determine whether the mixed process reaches the composition range of the new molten steel, thereby completing the division and tracking of the mixed casting billet.

[0096] (4) According to the composition content of the mixed casting billet calculated by the model, combined with the casting speed and the production section specification, the position of the mixed casting billet is tracked in real time.

[0097] (5) According to the composition requirement and the composition content of the mixed casting billet at each position, the starting point of flame cutting that meets the composition requirement is determined, and according to the composition requirement of the next furnace composition and the composition content of the mixed casting billet at each position, the end point of the mixed casting billet cutting is determined. The continuous casting billet between the starting point and the end point is the mixed casting billet.

[0098] (6) The mixed casting billet composition and cutting data obtained by the above method are stored and analyzed, combined with the composition requirement of the planned production steel grade, the production order of the shortest mixed casting billet is calculated, thereby determining the casting plan of the subsequent production steel grade.

Claims

1. A method for calculating a mixing concentration of molten steel in a continuous casting tundish, characterized by comprising: Comprising the following steps: ​ S1: iteratively calculate the solute mixing degree at the current time by using the following formula: ； Wherein, R1 is the current cycle solute mixing degree, R0 is the previous cycle solute mixing degree; where D lw is the weight of the steel in the tundish, which is obtained by the following equation: ； wherein: L w1 L is the large package weight for the current period w0 L is the large package weight for the previous period where D m is the weight of the steel flowing into the crystallizer, which is obtained by the following equation; ； where D tw is the change in tundish bath weight, which is obtained by the following equation: ； In the formula: T w1 is the intermediate ladle weight at the current time, T w0 is the intermediate ladle weight at the previous cycle; S2: compare R1 with the standard value, if it is consistent, it is determined that the molten steel entering the continuous caster at this time meets the requirements; if it is not consistent, step S1 is repeated again.

2. The method according to claim 1, characterized in that: In step S2, comprising the following steps: S2.1: determine the solute mixing degree range of continuous casting steel grade For a specified chemical composition, the solute mixing degree range is calculated respectively, and E is the element symbol; Let the previous steel grade be S0, and the current mixed pouring steel grade be S1; for each mixed pouring element E, each steel grade has its own chemical composition range, and each chemical composition range is divided into an upper limit E u , a lower limit E d , and a standard value E s ; The maximum solute mixing degree of E element of the previous molten steel is determined by using the following calculation formula: ； R E0 is the upper limit value of the degree of mixing of the chemical element solutes in the molten steel of the previous heat; E u0 upper limit value for the chemical composition of the previous heat of steel E s0 standard value for the chemical composition of the previous heat of steel; E S1 is the standard value of the chemical composition of the current molten steel The minimum solute mixing degree of E element of the current molten steel is determined by using the following calculation formula: ； R E1 is the current furnace molten steel chemical element solute mixing degree lower limit value; E d1 is the lower limit value of the chemical composition of the current molten steel S2.2 Compare R1 with standard value R E0 and R E1 . If R1∈[R E0 ,R E1 ], then it is compliant; otherwise, it is non-compliant.

3. The method according to claim 1, characterized in that: In step S2, comprising the following steps: S2.1: determine the range of each element in the tundish According to the value of R1 and the initial content of each element in the ladle and tundish, the content of each element in the current tundish is calculated; S2.2: compare the content range of the specified chemical composition with the content of the corresponding element in S2.1, if they all meet the range requirements, it is consistent; otherwise, it is not consistent.

4. The method according to claim 1, characterized in that: If it is determined to be consistent in S2, the steel plate corresponding to the molten steel entering the continuous caster is the steel grade that meets the requirements, which can be segmented at the corresponding position, and the segmented steel plate is the steel plate that meets the requirements.

5. The method of claim 1, wherein the method is characterized by: The cycle is 5s.

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