Method for intelligently analyzing LF refining production time and power supply parameters

Abstract

The invention relates to a method for intelligently analyzing LF refining production time and power supply parameters. An intelligent model is compiled, data in a first-level PLC, a second-level material calculation system and a third-level MES are collected in real time through a computer, manual experience data input is combined, and the LF refining production time and the power supply time are effectively predicted through a model series algorithm. The method has the characteristic of low cost for refining production, can effectively and accurately predict the production time of LF refining and the optimal power supply parameters conforming to the continuous casting tundish temperature, and ensures that refined molten steel can meet the target temperature and the subsequent casting blank quality after being conveyed to continuous casting.

Description

Technical Field

[0001] The present invention belongs to the technical field of steelmaking production processes, and particularly relates to a method for intelligently analyzing the production time and power supply parameters of LF refining production. Background Art

[0002] In the field of steel manufacturing, LF refining is a key process for improving the quality of molten steel. By adjusting the chemical composition and temperature of the molten steel, it can meet the performance requirements of different products. This process is crucial for producing high-quality steel because it can remove impurities such as oxygen, sulfur, and phosphorus in the molten steel, and at the same time adjust the carbon content and the content of other alloying elements to achieve the required steel grade specifications.

[0003] In LF refining production, the production time and power supply time of refining are key factors determining the quality of molten steel. During the refining process, impurity elements such as sulfur and oxygen in the molten steel will combine with the components in the slag through chemical reactions and be removed. If the refining time is too short, the impurities in the molten steel cannot be completely removed, which may lead to unqualified quality of the final product, especially in the production of steel grades with high requirements for composition accuracy. Although a too long refining time helps to further remove impurities, it will increase energy consumption and production costs, and may cause excessive oxidation of the molten steel, affecting the composition and performance of the molten steel. Therefore, the optimization of the refining production time needs to balance the relationship between impurity removal and energy costs. The power supply time is closely related to the power supply voltage and current, and is an important factor affecting the heating and reaction rate of the molten steel. During the LF refining process, arc heating is the main heat source, and the power supply current and voltage determine the temperature in the furnace and the heating rate of the molten steel. If the power supply time is too long, it may cause the temperature of the molten steel to be too high, affecting the composition stability of the molten steel, and even may cause local overheating in the furnace, thus damaging the quality of the molten steel. If the power supply time is too short, the molten steel may not be heated sufficiently and the reaction may not be complete, affecting the refining effect. Therefore, reasonably controlling the power supply time is crucial for maintaining the stable temperature and reaction rate of the molten steel.

[0004] The tundish is a transition container for the molten steel to reach the continuous casting machine after the LF furnace refining is completed. Before the continuous casting production starts, the temperature of the molten steel in the tundish needs to reach a certain standard to ensure the smooth progress of the subsequent continuous casting process. If the temperature of the molten steel is too low, it may lead to problems such as too slow casting speed, uneven solidification of the molten steel, and even casting fracture; while too high a temperature may cause excessive oxidation of the molten steel, increase energy consumption, and affect the compositional uniformity during the casting process, thereby affecting the product quality.

[0005] Therefore, accurately controlling the production time and power supply time of LF refining is of crucial significance for improving production efficiency and ensuring the quality of the final product.

[0006] There are two traditional methods for controlling the refining production time and power supply time:

[0007] One is to adopt a fixed - mode production, that is, to formulate a set of fixed production processes according to historical data and experience. The refining production time and power supply time are carried out according to the preset procedures. For example, some steel mills set the refining production time to 40 minutes and the power supply time to 20 minutes. However, this approach ignores the dynamic changes in the actual production process, such as fluctuations in raw material components and changes in equipment status, resulting in a certain degree of resource waste in the production process.

[0008] The second is to estimate the refining production time and power supply time through manual experience. The on - site operators control the production time and power supply time according to the actual situation of each furnace and their own production operation experience. However, this approach is limited by the subjective judgment and experience level of the operators, and there are certain limitations. Moreover, it does not fully consider production scheduling, as well as influencing factors such as whether the molten steel can reach the target temperature, the drawing speed of the continuous caster, and the temperature loss caused by the transportation process, which is likely to cause fluctuations in product quality. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for intelligently analyzing the refining production time and power supply parameters of LF refining. By writing an intelligent model, using a computer to collect data from the first - level PLC, second - level material calculation system, and third - level MES in real - time, combined with the input of manual experience data, the effective prediction of the LF refining production time and power supply time is realized through a series of model algorithms, solving the problems in the background technology.

[0010] The technical solution for solving the above - mentioned technical problems is as follows:

[0011] A method for intelligently analyzing the refining production time and power supply parameters of LF refining. First, install a computer at the LF refining site, connect the computer to the data networks of the first - level PLC, second - level material calculation system, and third - level MES, and install a model for intelligently analyzing the refining production time and power supply parameters in the computer; proceed according to the following steps:

[0012] Step 1: Enter basic information into the computer, including: the transportation time correspondence table from LF refining to the continuous caster, the molten steel temperature drop speed table for different ladle conditions, the molten steel temperature change table caused by adding different materials, the LF refining power supply system parameters, and the search range table of gear voltage and gear current based on the characteristics of the power supply system.

[0013] The transportation time correspondence table is a correspondence table between the continuous caster number and the corresponding transportation time. When a specific continuous caster number is input into the computer, the computer can, according to the corresponding relationship in the table, feedback the corresponding transportation time;

[0014] The steel temperature drop rate table for different ladle conditions is a table showing the corresponding relationship between ladle codes and the corresponding steel temperature drop rates; when a specific ladle condition code is input into the computer, the computer can, according to the corresponding relationship in the table, feedback the corresponding steel temperature drop rate.

[0015] The steel temperature change table caused by adding different materials is a table showing the corresponding relationship between each material and the corresponding temperature change coefficient; when a specific material name is input into the computer, the computer can, according to the corresponding relationship in the table, calculate the corresponding temperature change value.

[0016] Step 2: The computer determines whether the LF refining is in the production state by detecting the ladle capping signal. If so, it proceeds to Step 3.

[0017] Step 3: The computer reads the following data from the third-level MES system:

[0018] The current LF refining production plan, including the weight, temperature, ladle condition of the molten steel entering the station and the resulting temperature drop rate; the casting plan information of the subsequent continuous caster, including the caster number and transportation time, tundish target temperature, slab cross-sectional area, molten steel density, empty ladle weight of the tundish, and the remaining molten steel weight of the tundish required by the process control.

[0019] The computer reads the information on the weight of the bulk materials and alloys to be added in the LF refining from the second-level material calculation system, and according to the steel temperature change table caused by adding different materials in Step 1, calculates the steel temperature change caused by adding materials according to Equation (1):

[0020] Lost _Mat_i =Mat _i ·T _drop_i (1)

[0021] In the formula: Lost_Mat_i—the temperature change of the molten steel caused by adding materials, unit: °C;

[0022] Mat_i—the amount of material added, unit: ton;

[0023] T_drop_i—the temperature change coefficient caused by the material, unit: °C / ton.

[0024] Summarize the temperature changes of the molten steel caused by various materials, and calculate the total temperature change caused by adding materials according to Equation (2):

[0025]

[0026] In the formula: Lost _Mat —the total temperature change of the molten steel caused by various materials, unit: °C;

[0027] Lost _Mat_i——Temperature changes caused by various feedings, unit: °C.

[0028] Step 4: The computer reads the casting speed of the continuous caster corresponding to the production plan in the first-level PLC at the current moment, combines the cross-sectional area of the billet and the molten steel density data obtained in Step 3, and calculates the weight of molten steel that can be poured out per minute according to Equation (3), that is:

[0029] Wt_ cast = S·Dens·V (3)

[0030] In the formula: Wt_cast—the weight of molten steel that can be poured out per minute, unit: ton / min;

[0031] S—the cross-sectional area of the billet, unit: m 2 ;

[0032] Dens—the density of molten steel, ton / m 3 ;

[0033] V—the casting speed of the continuous caster, unit: m / min.

[0034] Step 5: The computer reads the weighing weight data of the tundish turntable in the first-level PLC at the current moment, combines the empty tundish weight obtained in Step 3 and the remaining molten steel weight required by the process control, and combines the weight of molten steel that can be poured out per minute in Step 4, and calculates the remaining casting time according to Equation (4), that is:

[0035] Time _cast =(Wt - Wt _GB - Wt _Last ) / Wt _cast (4)

[0036] In the formula: Time_cast—the remaining casting time of the current continuous caster for the corresponding heat, unit: min;

[0037] Wt—the current weighing weight of the tundish turntable, unit: ton;

[0038] Wt_GB—the current empty tundish weight, unit: ton;

[0039] Wt_Last—the remaining molten steel weight of the tundish, unit: ton;

[0040] Wt_cast—the weight of molten steel that can be poured out per minute, unit: ton / min

[0041] Step 6: According to the remaining teeming time obtained in Step 5 and the transportation time required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process obtained in Step 3, calculate the LF refining production time of the current heat that meets the continuous casting production schedule according to Equation (5), that is:

[0042] Time _LF = Time _cast - Time _transp ort (5)

[0043] In the formula: Time_ LF ——The LF refining production time of the current heat, unit: min;

[0044] Time_ cast ——The remaining teeming time of the corresponding heat of the current continuous caster, unit: min;

[0045] Time _transport ——The transportation time required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process, unit: min

[0046] Step 7: According to the temperature drop rate of the molten steel under different ladle conditions and the molten steel transportation time in Step 3, calculate the temperature loss Lost during transportation according to Equation (6) _Transport ;

[0047] Lost _Transport = Time _transport ·V 损失 (6)

[0048] In the formula: Lost _Transport ——The temperature loss during transportation, unit: °C;

[0049] Time_ transport ——The molten steel transportation time, unit: min;

[0050] V 损失 ——The temperature drop rate of the molten steel under different ladle conditions, unit: °C / min.

[0051] Furthermore, combined with the tundish target temperature in Step 3, calculate the temperature that the molten steel needs to reach when leaving the LF refining according to Equation (7) as:

[0052] Temp _LF_Out = Temp _tundish + Lost _Transport (7)

[0053] In the formula: Temp _LF_Out ——The LF refining outgoing target temperature, unit: °C;

[0054] Temp _tundish —— The target temperature of the tundish for continuous casting, unit: °C;

[0055] Lost _Transport —— Temperature loss during transportation, unit: °C;

[0056] Step 8: Calculate the temperature loss of the molten steel caused by the ladle condition during the LF refining process according to Equation (8):[[ID=~]]

[0057] Lost _LF = Time _LF ·V 损失 (8)

[0058] In the formula: Lost _LF —— Temperature loss caused by the ladle condition during the LF refining process, °C; Time _LF ——

[0059] LF refining production time, min;

[0060] V 损失 —— Temperature drop rate of the molten steel under different ladle conditions, unit: °C / min

[0061] Step 9: Calculate the total temperature that the molten steel needs to be raised according to the incoming temperature of the molten steel for LF refining, the total temperature change of the molten steel caused by various materials, the target temperature of the molten steel leaving the LF refining in Step 7, and the temperature loss caused by the ladle condition in Step 8 according to Equation (9):

[0062] dT = K0·(Temp _LF_Out - T _Begin + Lost _LF + Lost _Mat ) (9)

[0063] In the formula: dT—— Total temperature that the molten steel needs to be raised, unit: °C;

[0064] K0—— Heating threshold, value is 1.0 - 1.2;

[0065] Temp _LF—Out —— Target temperature of the molten steel leaving the LF refining, unit: °C;

[0066] T _Begin —— Incoming temperature of the molten steel for LF refining, unit: °C;

[0067] Lost _LF —— Temperature loss caused by the ladle condition during the LF refining process, °C;

[0068] Lost _Mat——Total temperature change of molten steel caused by various materials during LF refining, °C.

[0069] Step 10: Calculate the additional heat required to reach the target temperature of the molten steel based on the total temperature to be raised for the molten steel obtained in Step 9 and the weight of the molten steel in Step 3 according to Equation (10):

[0070] Q = C·Steel _wt ·dT (10)

[0071] Where: Q——Total heat required, unit: KJ;

[0072] C——Specific heat of molten steel, default is 460 KJ / ton / K;

[0073] Steel _wt ——Weight of molten steel, unit: ton;

[0074] dT——Total temperature to be raised for the molten steel, unit °C.

[0075] Based on the total heat T, the set average power supply P can be calculated according to Equation (11), that is:

[0076] P = 3600·Q / (Time _Hot ·60) / 1000 (11)

[0077] Where: P——Set average power supply, unit: kW;

[0078] Q——Total heat required, unit: KJ;

[0079] Time _Hot ——Heating time required for the molten steel, unit min.

[0080] Time _Hot Is half of the total LF refining time, that is: Time _Hot = Time _LF / 2

[0081] Step 11: According to the power supply parameters of the LF refining power supply equipment in Step 1, calculate the corresponding useful arc power Pi for all gear voltages and gear currents under the corresponding power supply equipment according to Equations (12)-(14), that is:

[0082]

[0083]

[0084]

[0085] Where: U i—— A certain voltage level of the power supply system, unit: V;

[0086] I i —— A certain current level of the power supply system, unit: kA.

[0087] S i —— The representative power corresponding to a certain voltage and current level, unit: kW;

[0088] Q i —— The reactive power corresponding to a certain voltage and current level, unit: kW;

[0089] P i —— The active power corresponding to a certain voltage and current level, unit: kW;

[0090] a1 - The rated power corresponding to the power supply system, built-in in the system, unit: kW;

[0091] b1 - The rated voltage corresponding to the power supply system, built-in in the system, unit: V;

[0092] c1 - The short - circuit impedance corresponding to the power supply system, built-in in the system, unit: Ω.

[0093] For the power supply system corresponding to LF refining, calculate the active power corresponding to all voltage levels and current levels. Then, by comparing the set average power P of the power supply with the active power P of the arc corresponding to all voltage levels and current levels one by one, find the P closest to P according to Equation (15) i and the corresponding voltage level and current, that is: i min(|P - P

[0094] |) (15) i |) (15)

[0095] Step 12: Reflect the calculated production time of the current heat of LF refining and the results of the power supply voltage and current on the computer screen for guiding on - site production.

[0096] Step 13: The computer continues to read the data of the first - level PLC of LF refining in real - time. When it detects that LF refining is in a shutdown state, the computer clears the production time of the current heat of LF refining and the results of the power supply voltage and current obtained in Step 12.

[0097] Step 14: Repeat the operations in Step 2 to Step 12 to achieve the tracking calculation of the production time and the results of the power supply voltage and current for different heats during the LF refining production process.

[0098] The above method for intelligently analyzing the production time and power supply parameters of LF refining, wherein the parameters of the LF refining power supply system include rated power, rated voltage and short-circuit impedance.

[0099] The above method for intelligently analyzing the production time and power supply parameters of LF refining. In step 2, the computer determines whether the LF refining is in the production state by detecting the ladle capping signal. Specifically, when the ladle capping signal at the current station is detected as Ture and the bottom blowing argon flow rate data is greater than 0 L / min, it indicates that the LF refining is in the production state; in step 13, when the ladle capping signal at the current station is detected as False and the bottom blowing argon flow rate data is equal to 0 L / min, it indicates that the LF refining is in the shutdown state.

[0100] The above method for intelligently analyzing the production time and power supply parameters of LF refining, wherein the model installed in the computer for intelligently analyzing the production time and power supply parameters of LF refining is an artificial intelligence model written in the Python programming language.

[0101] The above method for intelligently analyzing the production time and power supply parameters of LF refining, wherein the computer selects the Modbus protocol for communication with the first-level PLCs at the LF refining site and the continuous casting site to ensure efficient data transmission and real-time interaction; the computer communicates with the on-site second-level material calculation system and the third-level MES system using the Oracle database protocol. Through the interaction mode of the database, it ensures the stable storage and accurate call of data, providing reliable data support for intelligent analysis.

[0102] The beneficial effects of this invention are as follows:

[0103] Since no additional hardware equipment needs to be added, it has the characteristics of low cost for refining production, and can effectively and accurately predict the production time of LF refining and the optimal power supply parameters that meet the tundish temperature of continuous casting, ensuring that the molten steel after refining can meet the target temperature and the subsequent slab quality when it arrives at continuous casting, which has very important significance. Specific embodiments

[0104] The following further illustrates the present invention through specific Examples 1-5.

[0105] In Examples 1 - 5, first, a computer is installed at the LF refining site. The computer is connected to the primary PLCs at the LF refining site and the continuous casting site through Modbus protocol communication to ensure efficient data transmission and real - time interaction; the computer communicates with the secondary material calculation system and the tertiary MES system on - site through Oracle database protocol. Through the interaction of the database, stable data storage and accurate calling are ensured, providing reliable data support for intelligent analysis; an artificial intelligence model for intelligently analyzing the LF refining production time and power supply parameters is installed in the computer; this model is an artificial intelligence model written in the Python programming language.

[0106] Then, it is necessary to manually input basic information according to Step 1, specifically including:

[0107] Step 1: The corresponding table of the transportation time of molten steel from LF refining to the continuous caster, that is: when a specific continuous caster number is input into the computer, the computer can, according to the corresponding relationship in the table, feedback the corresponding transportation time, and these times are artificial experience values accumulated over a long time.

[0108] Continuous casting machine number Molten steel transportation time [min] 1CC 7 2CC 6 3CC 6

[0109] The table of the temperature - drop rate of molten steel corresponding to different ladle conditions, that is: when a specific ladle condition code is input into the computer, the computer can, according to the corresponding relationship in the table, feedback the corresponding temperature - drop rate of molten steel, and these rate values are artificial experience values accumulated over a long time.

[0110] Ladle condition code Temperature reduction rate / ℃ / min 1 0.1 1A 0.2 2 0.3 2A 0.4 3 0.5 3A 0.6 4 0.7 4A 0.8 5 0.9 5A 1 6 1.1 6A 1.2

[0111] The table of the temperature change of molten steel caused by the addition of different materials, that is: when a specific material name is input into the computer, the computer can, according to the corresponding relationship in the table, feedback the corresponding temperature change coefficient, and these coefficients are artificial experience values accumulated over a long time.

[0112] Material name Temperature change coefficient [℃ / ton] Fluorite -18 Slag melting agent -15 Ferromanganese -15 Ferrotitanium -7 Wollastonite -15 Lime -15 Low-aluminum ferrosilicon +15 Ferrosilicon +15 Ferrochrome -12 Aluminum wire +4 Calcium wire -50 Carburizer -45

[0113] Note: In the table, “-” represents the temperature drop of molten steel, and “+” represents the temperature increase of molten steel.

[0114] The relevant parameters of the LF refining power supply system, specifically including: the rated power is 5000kW, the rated voltage is 350V, the short - circuit impedance is 0.5Ω. In addition, there is also a search range table for the voltage and current of the power supply gear.

[0115]

[0116]

[0117] After completing Step 1, the following will separately describe Examples 1 - 5 in Steps 2 - 14.

[0118] Example 1:

[0119] Step 2: The computer reads the data of the first - level PLC of LF refining in real - time. When it detects that the ladle capping signal is True and the bottom - blowing argon gas flow rate data is 300 L / min, it determines that LF refining is in the production state.

[0120] Step 3: The computer reads the current LF refining production plan from the third - level MES system: the weight of the incoming molten steel is 100 tons, the temperature of the incoming molten steel is 1500 °C, and the ladle condition code is 3. According to the ladle condition code, the temperature drop rate of the molten steel can be found to be 0.5 °C / min. The subsequent plan is to cast at the 2CC continuous caster. From the caster number, it can be known that the molten steel transportation time is 6 min, the tundish target temperature is 1530 °C, the cross - sectional area of the slab is 0.2 m 2 , the density of the molten steel is 7.0 ton / m 3 , the empty - ladle weight of the continuous - casting tundish is 20 tons, and the required remaining molten steel weight in the tundish for process control is 5 tons.

[0121] The computer reads from the second - level material calculation system: it is set to add 1.0 ton of lime, 0.3 ton of ferrosilicon, and 0.2 ton of ferromanganese. Calculate the change in molten - steel temperature caused by the addition of materials according to Equation (1):

[0122] Lost _Mat_i =Mat _i ·T _drop_i (1)

[0123] In the formula: Lost_Mat_i—the change in molten - steel temperature caused by adding materials, unit: °C;

[0124] Mat_i—the amount of material added, unit: ton;

[0125] T_drop_i—the temperature change coefficient caused by the material, unit: °C / ton.

[0126] According to the table of the change in molten - steel temperature caused by adding different materials in Step 1, the temperature change coefficient of lime is - 15 °C / ton, the temperature change coefficient of ferrosilicon is 15 °C / ton, and the temperature coefficient of ferromanganese is - 15 °C / ton. Then:

[0127] The temperature change caused by lime: Lost _Mat_1 =1.0×(-15)= - 15 °C

[0128] The temperature change caused by ferrosilicon: Lost _Mat_2 =0.300×15=4.5 °C

[0129] Temperature change caused by ferromanganese: Lost _Mat_3 = 0.2 × (-15) = -3 °C

[0130] Summarize the temperature changes of the molten steel caused by lime, ferrosilicon, and ferromanganese, and calculate the total temperature change caused by the addition of materials according to Equation (2):

[0131]

[0132] In the formula: Lost _Mat —— The total temperature change of the molten steel caused by various materials, unit: °C;

[0133] Lost _Mat_i —— The temperature change caused by various types of feeding, unit: °C.

[0134] Then the total temperature change Lost _Mat = -15 + 4.5 - 3 = -13.5 °C.

[0135] Step 4: The computer reads the casting speed of the continuous caster corresponding to the production plan in the first-level PLC at the current moment, combines the slab cross-sectional area and molten steel density data obtained in Step 3, and calculates the weight of molten steel that can be poured out per minute according to Equation (3), that is:

[0136] Wt_ cast = S · Dens · V (3)

[0137] In the formula: Wt_cast —— The weight of molten steel that can be poured out per minute, unit: ton / min;

[0138] S —— The slab cross-sectional area, unit: m 2 ;

[0139] Dens —— The molten steel density ton / m 3 ;

[0140] V —— The casting speed of the continuous caster, unit: m / min.

[0141] The casting speed of the continuous caster in the first-level PLC at the current moment is 1.5 m / min. Combining the slab cross-sectional area and molten steel density, calculate the weight of molten steel poured out per minute according to Equation (3):

[0142] Wt _cast = 0.2 × 7.0 × 1.5 = 2.1 ton / min

[0143] Step 5: The computer reads the weighing weight data of the continuous casting ladle turntable in the first-level PLC at the current moment, which is 80t. Combining the empty ladle weight of 20t obtained in Step 3 and the remaining steel weight of 5t required by the process control, and combining the weight of molten steel that can be poured out per minute in Step 4, calculate the remaining casting time according to Equation (4), that is:

[0144] Time _cast =(Wt - Wt _GB - Wt _Last ) / Wt _cast (4)

[0145] =(80 - 20 - 5) / 2.1 = 26.2min

[0146] In the formula: Time_cast - the remaining casting time of the corresponding heat of the current continuous caster, unit: min;

[0147] Wt - the weighing weight of the current ladle turntable, unit: ton;

[0148] Wt_GB - the weight of the current empty ladle, unit: ton;

[0149] Wt_Last - the remaining steel weight of the ladle, unit: ton;

[0150] Wt_cast - the weight of molten steel that can be poured out per minute, unit: ton / min

[0151] Step 6: According to the remaining casting time of 26.2min obtained in Step 5 and the transportation time of 6min required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process in Step 3, calculate the LF refining production time of the current heat that meets the continuous casting production schedule according to Equation (5), that is:

[0152] Time _LF = Time _cast - Time _transport (5)

[0153] = 26.2 - 6 = 20.2min

[0154] In the formula: Time_ LF - the LF refining production time of the current heat, unit: min;

[0155] Time_ cast - the remaining casting time of the corresponding heat of the current continuous caster, unit: min;

[0156] Time _transport - the transportation time required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process, unit: min

[0157] Step 7: According to the molten steel temperature drop rate of 0.5 °C / min of the No. 3 ladle in Step 3 and the molten steel transportation time of 6 min corresponding to the 2CC continuous caster, calculate the temperature loss Lost during transportation according to Equation (6). _Transport ;

[0158] Lost _Transport = Time _transport ·V 损失 (6)

[0159] = 6 × 0.5 = 3 °C

[0160] In the formula: Lost _Transport —— Temperature loss during transportation, unit: °C;

[0161] Time transport —— Molten steel transportation time, unit: min;

[0162] V 损失 —— Molten steel temperature drop rate under different ladle conditions, unit: °C / min.

[0163] Combined with the tundish target temperature of 1530 °C in Step 3, calculate the target temperature that the molten steel needs to reach when leaving the LF refining furnace according to Equation (7):

[0164] Temp _LF_Out = Temp _tundish + Lost _Transport (7)

[0165] = 1530 + 3 = 1533 °C

[0166] In the formula: Temp _LF_Out —— LF refining furnace outlet target temperature, unit: °C;

[0167] Temp _tundish —— Tundish target temperature, unit: °C;

[0168] Lost _Transport —— Temperature loss during transportation, unit: °C;

[0169] Step 8: According to the LF refining production time obtained in Step 6 and the molten steel temperature drop rate of 0.5 °C / min of the No. 3 ladle in Step 3, calculate the molten steel temperature loss caused by the ladle condition during the LF refining process according to Equation (8):

[0170] Lost _LF = Time _LF ·V 损失 (8)

[0171] 20.2 × 0.5 = 10.1 °C

[0172] Where: Lost _LF —— During the LF refining process, the temperature loss caused by the ladle condition, °C; Time _LF ——

[0173] The LF refining production time, min;

[0174] V 损失 —— The temperature drop rate of molten steel under different ladle conditions, unit: °C / min

[0175] Step 9: According to the incoming temperature of molten steel in LF refining of 1500 °C in Step 3, the total change in molten steel temperature caused by various materials of -13.5 °C, the target temperature of molten steel out of LF refining of 1533 °C in Step 7, and the temperature loss of 10.1 °C caused by the ladle condition in Step 8, calculate the total temperature that the molten steel needs to be raised according to Equation (9):

[0176] dT = K0·(Temp _LF_Out -T _Begin +Lost _LF +Lost _Mat (9)

[0177] = 1.1 × [1533 - 1500 + 10.1 - (-13.5)] = 62.3 °C

[0178] Where: dT—— The total temperature that the molten steel needs to be raised, unit: °C;

[0179] K0—— The heating threshold, value is 1.1;

[0180] Temp _LF—Out —— The target temperature of molten steel out of LF refining, unit: °C;

[0181] T _Begin —— The incoming temperature of molten steel in LF refining, unit: °C;

[0182] Lost _LF —— During the LF refining process, the temperature loss caused by the ladle condition, °C;

[0183] Lost _Mat —— During the LF refining process, the total change in molten steel temperature caused by various materials, °C.

[0184] Step 10: From the total temperature that the molten steel needs to be raised of 62.3 °C obtained in Step 9 and the weight of molten steel of 100 t in Step 3, calculate the additional heat required to reach the target temperature of molten steel according to Equation (10):

[0185] Q = C·Steel_wt ·dT (10)

[0186] =460×100×62.3=2.87×10 6 KJ

[0187] Where: Q——Total heat required, unit: KJ;

[0188] C——Specific heat of molten steel, default is 460 KJ / ton / K;

[0189] Steel _wt ——Weight of molten steel, unit: ton;

[0190] dT——Total temperature rise required for molten steel, unit: °C.

[0191] Heating time required for molten steel Time _Hot Is half of the total LF refining time, Time _Hot =20.2 / 2=10.1 min

[0192] From the total heat T, the set average power supply P can be calculated according to Equation (11), that is:

[0193] P = 3600 · Q / (Time _Hot · 60) / 1000 (11)

[0194] =3600×2.87×10 6 / (10.1×60) / 1000=1705 kW Where: P——Set average power supply, unit: kW;

[0195] Q——Total heat required, unit: KJ;

[0196] Step 11: According to the power supply parameters of the LF refining power supply equipment in Step 1, calculate the arc useful power P corresponding to all gear voltages and gear currents under the corresponding power supply equipment according to Equations (12)-(14) i That is:

[0197]

[0198]

[0199]

[0200] Where: U i ——A certain gear voltage of the power supply system, unit: V;

[0201] I i ——A certain gear current of the power supply system, unit: KA.

[0202] S i —— The characterized power corresponding to a certain gear voltage and current, unit: kW;

[0203] Q i —— The reactive power corresponding to a certain gear voltage and current, unit: kW;

[0204] P i —— The useful power corresponding to a certain gear voltage and current, unit: kW;

[0205] a1 —— The rated power corresponding to the power supply system, built in the system, unit: kW;

[0206] b1 —— The rated voltage corresponding to the power supply system, built in the system, unit: V;

[0207] c1 —— The short - circuit impedance corresponding to the power supply system, built in the system, unit: Ω.

[0208] For the power supply system corresponding to LF refining, calculate the useful power corresponding to all gear voltages and gear currents. Then, by comparing the set average power supply P with the arc useful power P i corresponding to all the corresponding gear voltages and gear currents one by one, find the P i closest to P according to formula (15). The gear voltage and current corresponding to the P i closest to 1705 kW are found by comparison. The gear voltage corresponding to the P

[0209] min(|P - P i |) (15)

[0210] Step 12: Display the calculated production time of 20.2 min, power supply voltage of 300 V, and power supply current of 8 KA for the current heat of LF refining on the screen to guide on - site production.

[0211] Step 13: The computer continues to read the LF refining level - 1 PLC data in real - time. When it detects that the ladle cover signal is False and the bottom - blowing argon gas flow data is 0 L / min, it indicates that LF refining is in a shutdown state. At this time, the computer clears the results and prepares for the calculation of the next heat.

[0212] Step 14: Repeat the operations in Step 2 to Step 12 to realize the tracking calculation of the production time, power supply voltage, and power supply current results for different heats during the LF refining production process.

[0213] Example 2:

[0214] Step 2: The computer reads the data of the first-level PLC in the LF refining process in real time. When it detects that the ladle cover signal is True and the flow rate of bottom-blown argon is 200 L / min, it determines that the LF refining is in the production state.

[0215] Step 3: The computer reads the current LF refining production plan from the third-level MES system: the weight of the molten steel entering the station is 110 tons, the temperature of the molten steel entering the station is 1510 °C, and the ladle condition code is 4. According to the ladle condition code, the temperature drop rate of the molten steel can be found to be 0.7 °C / min. The subsequent plan is to cast at the 1CC continuous caster. From the caster number, it can be known that the molten steel transportation time is 7 min, the target temperature of the tundish is 1535 °C, the cross-sectional area of the billet is 0.22 m 2 , and the density of the molten steel is 7.1 ton / m 3 , the empty ladle weight of the continuous caster's tundish is 21 tons, and the remaining molten steel weight required by the process control is 4 tons.

[0216] The computer reads from the second-level material calculation system: it is set to add 0.9 ton of lime, 0.35 ton of ferrosilicon, and 0.25 ton of ferromanganese; calculate the change in molten steel temperature caused by the addition of materials according to Equation (1):

[0217] Lost _Mat_i =Mat _i ·T _drop_i (1)

[0218] In the formula: Lost_Mat_i—the change in molten steel temperature caused by adding materials, unit: °C;

[0219] Mat_i—the amount of material added, unit: ton;

[0220] T_drop_i—the temperature change coefficient caused by the material, unit: °C / ton.

[0221] According to the molten steel temperature change table caused by the addition of different materials in Step 1, it can be known that the temperature change coefficient of lime is -15 °C / ton, the temperature change coefficient of ferrosilicon is 15 °C / ton, and the temperature coefficient of ferromanganese is -15 °C / ton; then:

[0222] The temperature change caused by lime: Lost _Mat_1 =0.9×(-15)=-13.5 °C

[0223] The temperature change caused by ferrosilicon: Lost _Mat_2 =0.35×15=5.25 °C

[0224] The temperature change caused by ferromanganese: Lost _Mat_3 =0.25×(-15)=-3.75 °C

[0225] Summarize the temperature changes of molten steel caused by lime, ferrosilicon, and ferromanganese, and calculate the total temperature change caused by the addition of materials according to Equation (2):

[0226]

[0227] In the formula: Lost _Mat —— The total temperature change of molten steel caused by various materials, unit: °C;

[0228] Lost _Mat_i —— The temperature change caused by various types of feeding, unit: °C.

[0229] Then the total temperature change Lost _Mat =-13.5 + 5.25 - 3.75 = -12 °C

[0230] Step 4: The computer reads the casting speed of the continuous caster corresponding to the production plan in the first-level PLC at the current moment once, combines the cross-sectional area of the billet and the molten steel density data obtained in Step 3, and calculates the weight of molten steel that can be poured out per minute according to Equation (3), that is:

[0231] Wt_ cast = S·Dens·V (3)

[0232] In the formula: Wt_cast—— The weight of molten steel that can be poured out per minute, unit: ton / min;

[0233] S—— The cross-sectional area of the billet, unit: m 2 ;

[0234] Dens—— The density of molten steel ton / m 3 ;

[0235] V—— The casting speed of the continuous caster, unit: m / min.

[0236] The casting speed of the continuous caster in the first-level PLC at the current moment is 1.6 m / min. Combining the cross-sectional area of the billet and the density of molten steel, calculate the weight of molten steel poured out per minute according to Equation (3):

[0237] Wt _cast = 0.22×7.1×1.6 = 2.49 ton / min

[0238] Step 5: The computer reads the weighing weight data of the tundish turntable scale in the first-level PLC at the current moment once, which is 85 t, and combines the empty tundish weight of 21 t and the remaining molten steel weight of 4 t required by the process control obtained in Step 3. Combining the weight of molten steel that can be poured out per minute in Step 4, calculate the remaining casting time according to Equation (4), that is:

[0239] Time _cast =(Wt - Wt_GB -Wt _Last ) / Wt _cast (4)

[0240] =(85 - 21 - 4) / 2.49 = 24.1 min

[0241] Where: Time_cast—the remaining steel pouring time of the current continuous caster for the corresponding heat, unit: min;

[0242] Wt—the weighing weight of the current ladle turntable, unit: ton;

[0243] Wt_GB—the weight of the empty ladle of the current ladle, unit: ton;

[0244] Wt_Last—the remaining steel weight in the ladle, unit: ton;

[0245] Wt_cast—the weight of molten steel that can be poured out per minute, unit: ton / min

[0246] Step 6: According to the remaining steel pouring time 24.1 min obtained in Step 5 and the transportation time 7 min required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process in Step 3, calculate the current heat LF refining production time that meets the continuous casting production schedule according to Equation (5), that is:

[0247] Time _LF = Time _cast - Time _transport (5)

[0248] = 24.1 - 7 = 17.1 min

[0249] Where: Time_ LF —the current heat LF refining production time, unit: min;

[0250] Time_ cast —the remaining steel pouring time of the current continuous caster for the corresponding heat, unit: min;

[0251] Time _transport —the transportation time required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process, unit: min

[0252] Step 7: According to the molten steel temperature drop rate of 0.7 °C / min of the No. 4 ladle and the molten steel transportation time of 7 min corresponding to the 1CC continuous caster in Step 3, calculate the temperature loss Lost during transportation according to Equation (6) _Transport ;

[0253] Lost _Transport = Time_transport ·V 损失 (6)

[0254] = 7 × 0.7 = 4.9 °C

[0255] In the formula: Lost _Transport ——Temperature loss during transportation, unit: °C;

[0256] Time_ transport ——Transportation time of molten steel, unit: min;

[0257] V 损失 ——Temperature drop rate of molten steel under different ladle conditions, unit: °C / min.

[0258] Combined with the target temperature of 1535 °C in the continuous casting tundish in step 3, according to formula (7), the target temperature that the molten steel needs to reach when leaving the LF refining station is:

[0259] Temp _LF_Out = Temp _tundish + Lost _Transport (7)

[0260] = 1535 + 4.9 = 1539.9 °C

[0261] In the formula: Temp _LF_Out ——Target temperature when leaving the LF refining station, unit: °C;

[0262] Temp _tundish ——Target temperature of the continuous casting tundish, unit: °C;

[0263] Lost _Transport ——Temperature loss during transportation, unit: °C;

[0264] Step 8: According to the LF refining production time obtained in step 6 and the temperature drop rate of 0.7 °C / min of the molten steel in ladle No. 4 in step 3, calculate the temperature loss of the molten steel caused by the ladle condition during the LF refining process according to formula (8):

[0265] Lost _LF = Time _LF ·V 损失 (8)

[0266] 17.1 × 0.7 = 11.97 °C

[0267] In the formula: Lost _LF ——Temperature loss caused by the ladle condition during the LF refining process, °C; Time _LF ——

[0268] LF refining production time, min;

[0269] V 损失 ——The temperature drop rate of molten steel under different ladle conditions, unit: ℃ / min

[0270] Step 9: According to the tapping temperature of molten steel in LF refining of 1510℃ in Step 3, the total change in molten steel temperature caused by various materials of -12℃, the target tapping temperature of 1539.9℃ in LF refining in Step 7, and the temperature loss of 11.97℃ caused by ladle conditions in Step 8, calculate the total temperature that the molten steel needs to be raised according to Equation (9):

[0271] dT = K0·(Temp _LF_Out -T _Begin +Lost _LF +Lost _Mat ) (9)

[0272] = 1.08×[1539.9 - 1510 + 11.97 - (-12)] = 57.4℃. In the formula: dT - the total temperature that the molten steel needs to be raised, unit: ℃;

[0273] K0 - the heating threshold value, with a value of 1.1;

[0274] Temp _LF—Out ——The target tapping temperature of LF refining, unit: ℃;

[0275] T _Begin ——The tapping temperature of molten steel in LF refining, unit: ℃;

[0276] Lost _LF ——During LF refining, the temperature loss caused by ladle conditions, ℃;

[0277] Lost _Mat ——During LF refining, the total change in molten steel temperature caused by various materials, ℃.

[0278] Step 10: Based on the total temperature that the molten steel needs to be raised of 57.4℃ obtained in Step 9 and the weight of molten steel of 110t in Step 3, calculate the additional heat required to reach the target temperature of molten steel according to Equation (10):

[0279] Q = C·Steel _wt ·dT (10)

[0280] = 460×110×57.4 = 2.89×10 6 KJ

[0281] In the formula: Q - the total heat required, unit: KJ;

[0282] C - the specific heat of molten steel, default value is 460 KJ / ton / K;

[0283] Steel _wt —— Weight of molten steel, unit: ton;

[0284] dT —— Total temperature to be raised for molten steel, unit: °C.

[0285] Heating time Time required for molten steel _Hot Is half of the total LF refining time, Time _Hot = 17.1 / 2 = 8.55 min

[0286] Based on the total heat T, the set average power supply P can be calculated according to Equation (11), that is:

[0287] P = 3600·Q / (Time _Hot ·60) / 1000 (11)

[0288] = (3600 × 2.89 × 10 6 / (8.55 × 60) / 1000) = 2034 kW

[0289] In the formula: P —— Set average power supply, unit: kW;

[0290] Q —— Total heat required, unit: KJ;

[0291] Step 11: According to the power supply parameters of the LF refining power supply equipment in Step 1, calculate the useful arc power Pi corresponding to all gear voltages and gear currents under the corresponding power supply equipment according to Equations (12)-(14), that is:

[0292]

[0293]

[0294]

[0295] In the formula: U i —— A certain gear voltage of the power supply system, unit: V;

[0296] I i —— A certain gear current of the power supply system, unit: KA.

[0297] S i —— Representational power corresponding to a certain gear voltage and current, unit: kW;

[0298] Q i —— Reactive power corresponding to a certain gear voltage and current, unit: kW;

[0299] P i——Useful work power corresponding to a certain gear voltage and current, unit: kW;

[0300] a1——Rated power corresponding to the power supply system, built-in in the system, unit: kW;

[0301] b1——Rated voltage corresponding to the power supply system, built-in in the system, unit: V;

[0302] c1——Short-circuit impedance corresponding to the power supply system, built-in in the system, unit: Ω.

[0303] For the power supply system corresponding to LF refining, calculate the useful work power corresponding to all gear voltages and gear currents. Then, by comparing the set average power supply P with the arc useful work power P i corresponding to all corresponding gear voltages and gear currents one by one, find the P i closest to P according to formula (15). By comparison, find the P i corresponding to the gear voltage of 360V and current of 8.5KA closest to 2034kW.

[0304] min(|P - P i |) (15)

[0305] Step 12: Display the calculated production time of 17.1 min, power supply voltage of 360V, and power supply current of 8.5KA for the current heat of LF refining on the screen to guide on-site production.

[0306] Step 13: The computer continues to read the LF refining level 1 PLC data in real time. When it detects that the ladle cover signal is False and the bottom blowing argon flow data is 0 L / min, it indicates that LF refining is in a shutdown state. At this time, the computer clears the results and prepares for the calculation of the next heat.

[0307] Step 14: Repeat the operations in Step 2 to Step 12 to realize the tracking calculation of the production time, power supply voltage, and power supply current results for different heats during the LF refining production process.

[0308] Example 3:

[0309] Step 2: The computer reads the LF refining level 1 PLC data in real time. When it detects that the ladle cover signal is True and the bottom blowing argon flow data is 250 L / min, it determines that LF refining is in a production state.

[0310] Step 3: The computer reads the current LF refining production plan from the third-level MES system: the weight of the molten steel entering the station is 120 tons, the temperature of the molten steel entering the station is 1520 °C, and the ladle condition code is 5. According to the ladle condition code, the temperature drop rate of the molten steel can be found to be 0.9 °C / min. The subsequent plan is to cast at the 2CC continuous caster. Through the caster number, the molten steel transportation time is known to be 6 min, the tundish target temperature is 1540 °C, and the cross-sectional area of the billet is 0.25 m 2 , and the density of the molten steel is 7.2 ton / m 3 , the empty ladle weight of the continuous caster's tundish is 22 tons, and the remaining molten steel weight in the tundish required by the process control is 5 tons.

[0311] The computer reads from the second-level material calculation system: it is set to add 0.8 ton of lime, 0.4 ton of ferrosilicon, and 0.3 ton of ferromanganese; calculate the change in molten steel temperature caused by the addition of materials according to Equation (1):

[0312] Lost _Mat_i = Mat _i ·T _drop_i (1)

[0313] In the formula: Lost_Mat_i—the change in molten steel temperature caused by the addition of materials, unit: °C;

[0314] Mat_i—the amount of material added, unit: ton;

[0315] T_drop_i—the temperature change coefficient caused by the material, unit: °C / ton.

[0316] According to the table of the change in molten steel temperature caused by the addition of different materials in Step 1, the temperature change coefficient of lime is -15 °C / ton, the temperature change coefficient of ferrosilicon is 15 °C / ton, and the temperature coefficient of ferromanganese is -15 °C / ton; then:

[0317] The temperature change caused by lime: Lost _Mat_1 = 0.8×(-15) = -12 °C

[0318] The temperature change caused by ferrosilicon: Lost _Mat_2 = 0.4×15 = 6 °C

[0319] The temperature change caused by ferromanganese: Lost _Mat_3 = 0.3×(-15) = -4.5 °C

[0320] Sum up the temperature changes of the molten steel caused by lime, ferrosilicon, and ferromanganese, and calculate the total temperature change caused by the addition of materials according to Equation (2):

[0321]

[0322] In the formula: Lost_Mat —— Total temperature change of molten steel caused by various materials, unit: °C;

[0323] Lost _Mat_i —— Temperature change caused by various types of feeding, unit: °C.

[0324] Then the total temperature change Lost _Mat =-12 + 6 - 4.5 = -10.5 °C

[0325] Step 4: The computer reads the casting speed of the continuous caster corresponding to the production plan in the first-level PLC at the current moment once, which is 1.8 m / min. Combining the cross-sectional area of the billet and the molten steel density data obtained in Step 3, calculate the weight of molten steel that can be poured out per minute according to Equation (3), that is:

[0326] Wt_ cast = S·Dens·V (3)

[0327] In the formula: Wt_cast——Weight of molten steel that can be poured out per minute, unit: ton / min;

[0328] S——Cross-sectional area of the billet, unit: m 2 ;

[0329] Dens——Molten steel density ton / m 3 ;

[0330] V——Casting speed of the continuous caster, unit: m / min.

[0331] The casting speed of the continuous caster in the first-level PLC at the current moment is 1.8 m / min. Combining the cross-sectional area of the billet and the molten steel density, calculate the weight of molten steel poured out per minute according to Equation (3):

[0332] Wt _cast = 0.25×7.2×1.8 = 3.24 ton / min

[0333] Step 5: The computer reads the weighing weight data of the tundish turntable scale in the first-level PLC at the current moment once, which is 90 t. Combining the empty tundish weight of 22 t and the remaining molten steel weight of 5 t required by the process control obtained in Step 3, and combining the weight of molten steel that can be poured out per minute obtained in Step 4, calculate the remaining casting time according to Equation (4), that is:

[0334] Time _cast =(Wt - Wt _GB - Wt _Last ) / Wt _cast (4)

[0335] =(90 - 22 - 5) / 3.24 = 19.1 min

[0336] Where: Time_cast—the remaining steel-casting time of the current heat corresponding to the continuous caster, unit: min;

[0337] Wt—the weighing weight of the current ladle turret, unit: ton;

[0338] Wt_GB—the weight of the empty current ladle, unit: ton;

[0339] Wt_Last—the remaining steel weight in the ladle, unit: ton;

[0340] Wt_cast—the weight of the molten steel that can be poured out per minute, unit: ton / min

[0341] Step 6: According to the remaining steel-casting time of 19.1 min obtained in Step 5 and the transportation time of 6 min required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process obtained in Step 3, calculate the LF refining production time of the current heat that meets the continuous casting production schedule according to Equation (5), that is:

[0342] Time _LF = Time _cast - Time _transport (5)

[0343] = 19.1 - 6 = 13.1 min

[0344] Where: Time_ LF —the LF refining production time of the current heat, unit: min;

[0345] Time_ cast —the remaining steel-casting time of the current heat corresponding to the continuous caster, unit: min;

[0346] Time _transport —the transportation time required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process, unit: min

[0347] Step 7: According to the molten steel temperature drop rate of 0.9 °C / min of the No. 5 ladle and the molten steel transportation time of 6 min corresponding to the 1CC continuous caster in Step 3, calculate the temperature loss Lost during transportation according to Equation (6) _Transport ;

[0348] Lost _Transport = Time _transport ·V 损失 (6)

[0349] = 6 × 0.9 = 5.4 °C

[0350] Where: Lost _Transport—— Temperature loss during transportation, unit: °C;

[0351] Time_ transport —— Molten steel transportation time, unit: min;

[0352] V 损失 —— Temperature drop rate of molten steel under different ladle conditions, unit: °C / min.

[0353] Combined with the target temperature of 1540 °C in the continuous casting tundish in Step 3, when the molten steel leaves the LF refining station, the target temperature that the molten steel needs to reach is calculated according to Equation (7) as follows:

[0354] Temp _LF_Out =Temp _tundish +Lost _Transport (7)

[0355] =1540 + 5.4=1545.4 °C

[0356] In the formula: Temp _LF_Out —— Target temperature when the molten steel leaves the LF refining station, unit: °C;

[0357] Temp _tundish —— Target temperature of the continuous casting tundish, unit: °C;

[0358] Lost _Transport —— Temperature loss during transportation, unit: °C;

[0359] Step 8: According to the LF refining production time obtained in Step 6 and the temperature drop rate of 0.9 °C / min of the molten steel in the 5# ladle in Step 3, calculate the temperature loss of the molten steel caused by the ladle condition during the LF refining process according to Equation (8):

[0360] Lost _LF =Time _LF ·V 损失 (8)

[0361] 13.1×0.9=11.79 °C

[0362] In the formula: Lost _LF —— Temperature loss caused by the ladle condition during the LF refining process, °C; Time _LF ——

[0363] LF refining production time, min;

[0364] V 损失 —— Temperature drop rate of molten steel under different ladle conditions, unit: °C / min

[0365] Step 9: Based on the tapping temperature of 1520 °C of the LF-refined molten steel in Step 3, the total temperature change of the molten steel caused by various materials of -10.5 °C, the target tapping temperature of 1545.4 °C in Step 7 of the LF refining, and the temperature loss of 11.79 °C caused by the ladle condition in Step 8, calculate the total temperature that the molten steel needs to be raised according to Equation (9):

[0366] dT = K0·(Temp _LF_Out - T _Begin + Lost _LF + Lost _Mat ) (9)

[0367] = 1.1×[1545.4 - 1520 + 11.79 - (-10.5)] = 49.3 °C

[0368] In the formula: dT - the total temperature that the molten steel needs to be raised, unit: °C;

[0369] K0 - the heating threshold value, with a value of 1.1;

[0370] Temp _LF—Out - the target tapping temperature of the LF refining, unit: °C;

[0371] T _Begin - the tapping temperature of the LF-refined molten steel, unit: °C;

[0372] Lost _LF - the temperature loss caused by the ladle condition during the LF refining, °C;

[0373] Lost _Mat - the total temperature change of the molten steel caused by various materials during the LF refining, °C.

[0374] Step 10: Based on the total temperature of 49.3 °C that the molten steel needs to be raised obtained in Step 9 and the weight of the molten steel of 120 t in Step 3, calculate the additional heat required to reach the target temperature of the molten steel according to Equation (10):

[0375] Q = C·Steel _wt ·dT (10)

[0376] = 460×120×49.3 = 2.72×10 6 KJ

[0377] In the formula: Q - the total required heat, unit: KJ;

[0378] C - the specific heat of the molten steel, default value is 460 KJ / ton / K;

[0379] Steel _wt - the weight of the molten steel, unit: ton;

[0380] dT - The total temperature of the molten steel that needs to be raised, unit: °C.

[0381] The heating time required for molten steel _Hot Time is half of the total LF refining time. _Hot =13.1 / 2=6.55min

[0382] The set average power supply power P can be calculated from the total heat T according to formula (11), that is:

[0383] P=3600·Q / (Time _Hot 60) / 1000 (11)

[0384] =3600×2.72×10 6 / (6.55×60) / 1000=2497kW

[0385] Where: P——set average power supply power, unit: kW;

[0386] Q——total calories required, unit: KJ;

[0387] Step 11: Based on the power supply parameters of the LF refined power supply equipment in step 1, calculate the arc useful work power Pi corresponding to all gear voltages and gear currents of the corresponding power supply equipment according to equations (12)-(14), that is:

[0388]

[0389]

[0390]

[0391] Where: U i ——The voltage of a certain gear of the power supply system, unit: V;

[0392] I i ——Current in a certain gear of the power supply system, unit: KA.

[0393] S i ——The power corresponding to a certain voltage and current, unit: kW;

[0394] Q i ——Reactive power corresponding to a certain voltage and current, unit: kW;

[0395] P i ——The useful work power corresponding to a certain gear voltage and current, unit: kW;

[0396] a1——Rated power of the corresponding power supply system, built in the system, unit: kW;

[0397] b1——Rated voltage of the corresponding power supply system, built in the system, unit: V;

[0398] c1——Short - circuit impedance of the corresponding power supply system, built in the system, unit: Ω.

[0399] For the power supply system corresponding to LF refining, calculate the useful power corresponding to the voltage and current of all gears. Then, by comparing the set average power supply P with the arc useful power P i corresponding to the voltage and current of all gears one by one, find the P i closest to P according to formula (15). By comparison, find the P i corresponding to the gear voltage and current closest to 2497 kW. The corresponding gear voltage is 380 V and the current is 9.5 KA.

[0400] min(|P - P i |) (15)

[0401] Step 12: Display the calculated production time of 13.1 min, power supply voltage of 380 V, and power supply current of 9.5 KA for the current heat of LF refining on the screen to guide on - site production.

[0402] Step 13: The computer continues to read the LF refining level - 1 PLC data in real - time. When it detects that the ladle cover signal is False and the bottom - blowing argon gas flow data is 0 L / min, it indicates that LF refining is in a shutdown state. At this time, the computer clears the results and prepares for the calculation of the next heat.

[0403] Step 14: Repeat the operations in Step 2 to Step 12 to achieve the tracking calculation of the production time, power supply voltage, and power supply current results for different heats during the LF refining production process.

[0404] Example 4:

[0405] Step 2: The computer reads the LF refining level - 1 PLC data in real - time. When it detects that the ladle cover signal is True and the bottom - blowing argon gas flow data is 280 L / min, it determines that LF refining is in a production state.

[0406] Step 3: The computer reads the current LF refining production plan from the third - level MES system: the weight of the incoming molten steel is 115 tons, the temperature of the incoming molten steel is 1515 °C, and the ladle condition code is 4. According to the ladle condition code, the temperature drop rate of the molten steel can be found to be 0.7 °C / min. The subsequent plan is to cast on the 3CC continuous caster. Through the continuous caster number, the molten steel transportation time is known to be 6 min, the tundish target temperature is 1538 °C, and the cross - sectional area of the billet is 0.23 m2 , the density of molten steel is 7.15 ton / m 3 , the empty weight of the tundish for continuous casting is 21.5 tons, and the remaining molten steel weight in the tundish required by process control is 4.5 tons.

[0407] The computer reads from the secondary material calculation system: it is set to add 0.75 ton of lime, 0.38 ton of ferrosilicon, and 0.28 ton of ferromanganese; calculate the change in molten steel temperature caused by the addition of materials according to Equation (1):

[0408] Lost _Mat_i = Mat _i ·T _drop_i (1)

[0409] In the formula: Lost_Mat_i - the change in molten steel temperature caused by material addition, unit: °C;

[0410] Mat_i - the amount of material added, unit: ton;

[0411] T_drop_i - the temperature change coefficient caused by the material, unit: °C / ton.

[0412] According to the molten steel temperature change table caused by the addition of different materials in Step 1, it can be known that the temperature change coefficient of lime is -15 °C / ton, the temperature change coefficient of ferrosilicon is 15 °C / ton, and the temperature coefficient of ferromanganese is -15 °C / ton; then:

[0413] The temperature change caused by lime: Lost _Mat_1 = 0.75 × (-15) = -11.25 °C

[0414] The temperature change caused by ferrosilicon: Lost _Mat_2 = 0.38 × 15 = 5.7 °C

[0415] The temperature change caused by ferromanganese: Lost _Mat_3 = 0.28 × (-15) = -4.2 °C

[0416] Sum up the temperature changes of molten steel caused by lime, ferrosilicon, and ferromanganese, and calculate the total temperature change caused by the addition of materials according to Equation (2):

[0417]

[0418] In the formula: Lost _Mat —— the total change in molten steel temperature caused by various materials, unit: °C;

[0419] Lost _Mat_i —— the temperature change caused by various types of material addition, unit: °C.

[0420] Then the total temperature change Lost_Mat = -11.25 + 5.7 - 4.2 = -9.75 °C

[0421] Step 4: The computer reads the casting speed of the continuous caster corresponding to the production plan in the first-level PLC at the current moment once, which is 1.7 m / min. Combining with the cross-sectional area of the slab and the molten steel density data obtained in Step 3, the weight of molten steel that can be poured out per minute is calculated according to Equation (3), that is:

[0422] Wt_ cast = S·Dens·V (3)

[0423] In the formula: Wt_cast - the weight of molten steel that can be poured out per minute, unit: ton / min;

[0424] S - the cross-sectional area of the slab, unit: m 2 ;

[0425] Dens - the density of molten steel, ton / m 3 ;

[0426] V - the casting speed of the continuous caster, unit: m / min.

[0427] The casting speed of the continuous caster in the first-level PLC at the current moment is 1.7 m / min. Combining with the cross-sectional area of the slab and the density of molten steel, the weight of molten steel poured out per minute is calculated according to Equation (3):

[0428] Wt _cast = 0.23×7.15×1.7 = 2.76 ton / min

[0429] Step 5: The computer reads the weighing weight data of the tundish turntable scale in the first-level PLC at the current moment once, which is 88 t. Combining with the empty tundish weight of 21.5 t obtained in Step 3 and the remaining molten steel weight of 4.5 t required by the process control, and combining with the weight of molten steel that can be poured out per minute obtained in Step 4, the remaining casting time is calculated according to Equation (4), that is:

[0430] Time _cast = (Wt - Wt _GB - Wt _Last ) / Wt _cast (4)

[0431] = (88 - 21.5 - 4.5) / 2.76 = 22.5 min

[0432] In the formula: Time_cast - the remaining casting time of the current continuous caster corresponding to the heat, unit: min;

[0433] Wt - the weighing weight of the current tundish turntable scale, unit: ton;

[0434] Wt_GB——The current weight of the empty tundish, unit: ton;

[0435] Wt_Last——The remaining molten steel weight in the tundish, unit: ton;

[0436] Wt_cast——The weight of molten steel that can be poured per minute, unit: ton / min

[0437] Step 6: According to the remaining casting time of 22.5 min obtained in Step 5 and the transportation time of 6 min required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process obtained in Step 3, calculate the current heat LF refining production time that meets the continuous casting production schedule according to Equation (5), that is:

[0438] Time _LF =Time _cast -Time _transport (5)

[0439] =22.5 - 6=16.5min

[0440] In the formula: Time_ LF ——The current heat LF refining production time, unit: min;

[0441] Time_ cast ——The remaining casting time of the corresponding heat of the current continuous casting machine, unit: min;

[0442] Time _transport ——The transportation time required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process, unit: min

[0443] Step 7: According to the temperature drop rate of 0.7℃ / min of the molten steel in the No. 4 ladle and the molten steel transportation time of 6 min corresponding to the 1CC continuous casting machine in Step 3, calculate the temperature loss Lost during transportation according to Equation (6) _Transport ;

[0444] Lost _Transport =Time _transport ·V 损失 (6)

[0445] =6×0.7=4.2℃

[0446] In the formula: Lost _Transport ——The temperature loss during transportation, unit: ℃;

[0447] Time_ transport ——The molten steel transportation time, unit: min;

[0448] V 损失——The temperature drop rate of molten steel under different ladle conditions, unit: ℃ / min.

[0449] Combined with the tundish target temperature of 1538℃ in step 3, according to formula (7), when the molten steel leaves the LF refining station, the target temperature that the molten steel needs to reach is:

[0450] Temp _LF_Out =Temp _tundish +Lost _Transport (7)

[0451] =1538 + 4.2=1542.2℃

[0452] In the formula: Temp _LF_Out ——The target temperature when the molten steel leaves the LF refining station, unit: ℃;

[0453] Temp _tundish ——The target temperature of the tundish, unit: ℃;

[0454] Lost _Transport ——The temperature loss during transportation, unit: ℃;

[0455] Step 8: According to the LF refining production time obtained in step 6 and the molten steel temperature drop rate of 0.7℃ / min of the No. 4 ladle in step 3, calculate the temperature loss of the molten steel caused by the ladle condition during the LF refining process according to formula (8):

[0456] Lost _LF =Time _LF ·V 损失 (8)

[0457] 16.5×0.7=11.55℃

[0458] In the formula: Lost _LF ——The temperature loss caused by the ladle condition during the LF refining process, ℃; Time _LF ——

[0459] The LF refining production time, min;

[0460] V 损失 ——The molten steel temperature drop rate under different ladle conditions, unit: ℃ / min

[0461] Step 9: According to the molten steel inlet temperature of 1515℃ in step 3, the total temperature change of the molten steel caused by various materials of -9.75℃, the LF refining outlet target temperature of 1542.2℃ in step 7, and the temperature loss of 11.55℃ caused by the ladle condition in step 8, calculate the total temperature that the molten steel needs to be raised according to formula (9):

[0462] dT = K0·(Temp _LF_Out - T _Begin + Lost _LF + Lost _Mat ) (9)

[0463] = 1.06×[1542.2 - 1515 + 11.55 - (-9.75)] = 53.4℃

[0464] Where: dT - The total temperature to be raised for molten steel, unit: ℃;

[0465] K0 - The temperature rise threshold, with a value of 1.06;

[0466] Temp _LF—Out - The target temperature at the end of LF refining, unit: ℃;

[0467] T _Begin - The temperature of molten steel entering LF refining, unit: ℃;

[0468] Lost _LF - The temperature loss caused by the ladle condition during LF refining, ℃;

[0469] Lost _Mat - The total change in the temperature of molten steel caused by various materials during LF refining, ℃.

[0470] Step 10: Based on the total temperature to be raised for molten steel of 53.4℃ obtained in Step 9 and the weight of molten steel of 115t in Step 3, calculate the additional heat required to reach the target temperature of molten steel according to Equation (10):

[0471] Q = C·Steel _wt ·dT (10)

[0472] = 460×115×53.4 = 2.83×10 6 KJ

[0473] Where: Q - The total required heat, unit: KJ;

[0474] C - The specific heat of molten steel, default value is 460 KJ / ton / K;

[0475] Steel _wt - The weight of molten steel, unit: ton;

[0476] dT - The total temperature to be raised for molten steel, unit: ℃.

[0477] The heating time Time required for molten steel _Hot is half of the total LF refining time, Time _Hot= 16.5 / 2 = 8.25 min

[0478] From the total heat T, the set average power supply P can be calculated according to Equation (11), that is:

[0479] P = 3600·Q / (Time _Hot ·60) / 1000 (11)

[0480] = 3600 × 2.83 × 10 6 / (8.25 × 60) / 1000 = 2073 kW

[0481] Where: P - set average power supply, unit: kW;

[0482] Q - total heat required, unit: KJ;

[0483] Step 11: According to the power supply parameters of the LF refining power supply equipment in Step 1, calculate the arc useful power Pi corresponding to all gear voltages and gear currents under the corresponding power supply equipment according to Equations (12) - (14), that is:

[0484]

[0485]

[0486]

[0487] Where: U i - a certain gear voltage of the power supply system, unit: V;

[0488] I i - a certain gear current of the power supply system, unit: KA.

[0489] S i - the characteristic power corresponding to a certain gear voltage and current, unit: kW;

[0490] Q i - the reactive power corresponding to a certain gear voltage and current, unit: kW;

[0491] P i - the useful power corresponding to a certain gear voltage and current, unit: kW;

[0492] a1 - the rated power corresponding to the power supply system, provided by the system, unit: kW;

[0493] b1 - the rated voltage corresponding to the power supply system, provided by the system, unit: V;

[0494] c1 - the short - circuit impedance corresponding to the power supply system, provided by the system, unit: Ω.

[0495] For the power supply system corresponding to LF refining, calculate the useful power corresponding to the voltages and currents of all gears. Then, by comparing the set average power supply P with the arc useful power P i corresponding to the voltages and currents of all the corresponding gears one by one, find the P i closest to P according to formula (15). By comparison, find the P i corresponding to the gear voltage and current closest to 2073 kW. The gear voltage corresponding to P is 370 V and the current is 8.8 KA.

[0496] min(|P - P i |) (15)

[0497] Step 12: Display the calculated production time of 16.5 min, power supply voltage of 370 V, and power supply current of 8.8 KA for the current heat of LF refining on the screen to guide on-site production.

[0498] Step 13: The computer continues to read the LF refining level-1 PLC data in real time. When it detects that the ladle capping signal is False and the bottom blowing argon flow rate data is 0 L / min, it indicates that LF refining has stopped production. At this time, the computer clears the results and prepares for the calculation of the next heat.

[0499] Step 14: Repeat the operations in Step 2 to Step 12 to realize the tracking calculation of the production time, power supply voltage, and power supply current results of different heats during LF refining production.

[0500] Example 5:

[0501] Step 2: The computer reads the LF refining level-1 PLC data in real time. When it detects that the ladle capping signal is True and the bottom blowing argon flow rate data is 320 L / min, it determines that LF refining is in the production state.

[0502] Step 3: The computer reads the current LF refining production plan from the third-level MES system: the weight of the incoming molten steel is 125 tons, the temperature of the incoming molten steel is 1525 °C, and the ladle condition code is 5. According to the ladle condition code, the molten steel temperature drop rate can be found to be 0.9 °C / min. The subsequent plan is to cast at the 1CC continuous caster. Through the caster number, the molten steel transportation time is known to be 7 min, the tundish target temperature is 1545 °C, and the slab cross-sectional area is 0.26 m2 ， The molten steel density is 7.3 ton / m 3 , the empty ladle weight of the continuous caster is 23 tons, and the required remaining molten steel weight in the ladle for process control is 5 tons.

[0503] The computer reads from the secondary material calculation system: it is set to add 0.85 ton of lime, 0.42 ton of ferrosilicon, and 0.32 ton of ferromanganese; calculate the change in molten steel temperature caused by the addition of materials according to Equation (1):

[0504] Lost _Mat_i =Mat _i ·T _drop_i (1)

[0505] In the formula: Lost_Mat_i—the change in molten steel temperature caused by adding materials, unit: °C;

[0506] Mat_i—the amount of material added, unit: ton;

[0507] T_drop_i—the temperature change coefficient caused by the material, unit: °C / ton.

[0508] According to the molten steel temperature change table caused by the addition of different materials in Step 1, it can be known that the temperature change coefficient of lime is -15 °C / ton, the temperature change coefficient of ferrosilicon is 15 °C / ton, and the temperature coefficient of ferromanganese is -15 °C / ton; then:

[0509] The temperature change caused by lime: Lost _Mat_1 =0.85×(-15)=-12.75 °C

[0510] The temperature change caused by ferrosilicon: Lost _Mat_2 =0.42×15=6.3 °C

[0511] The temperature change caused by ferromanganese: Lost _Mat_3 =0.32×(-15)=-4.8 °C

[0512] Sum up the molten steel temperature changes caused by lime, ferrosilicon, and ferromanganese, and calculate the total temperature change caused by the addition of materials according to Equation (2):

[0513]

[0514] In the formula: Lost _Mat ——The total change in molten steel temperature caused by various materials, unit: °C;

[0515] Lost _Mat_i ——The temperature changes caused by various types of material additions, unit: °C.

[0516] Then the total temperature change Lost _Mat =-12.75 + 6.3 - 4.8=-11.25 °C

[0517] Step 4: The computer reads the casting speed of the continuous caster corresponding to the production plan in the first-level PLC at the current moment once, which is 1.9 m / min. Combining with the billet cross-sectional area and molten steel density data obtained in Step 3, calculate the weight of molten steel that can be poured out per minute according to Equation (3), that is:

[0518] Wt_ cast = S·Dens·V (3)

[0519] Where: Wt_cast——the weight of molten steel that can be poured out per minute, unit: ton / min;

[0520] S——the billet cross-sectional area, unit: m 2 ;

[0521] Dens——the molten steel density ton / m 3 ;

[0522] V——the casting speed of the continuous caster, unit: m / min.

[0523] The casting speed of the continuous caster in the first-level PLC at the current moment is 1.9 m / min. Combining with the billet cross-sectional area and molten steel density, calculate the weight of molten steel poured out per minute according to Equation (3):

[0524] Wt _cast = 0.26×7.3×1.9 = 3.47 ton / min

[0525] Step 5: The computer reads the weighing weight data of the tundish turntable scale in the first-level PLC at the current moment once, which is 92 t. Combining with the empty tundish weight of 23 t obtained in Step 3 and the remaining molten steel weight of 5 t required by the process control, and combining with the weight of molten steel that can be poured out per minute obtained in Step 4, calculate the remaining casting time according to Equation (4), that is:

[0526] Time _cast = (Wt - Wt _GB - Wt _Last ) / Wt _cast (4)

[0527] = (92 - 23 - 5) / 3.47 = 18.4 min

[0528] Where: Time_cast——the remaining casting time of the current continuous caster for the corresponding heat, unit: min;

[0529] Wt——the weighing weight of the current tundish turntable scale, unit: ton;

[0530] Wt_GB——the empty tundish weight of the current tundish, unit: ton;

[0531] Wt_Last——The remaining steel weight of the large package, unit: ton;

[0532] Wt_cast——The weight of molten steel that can be poured per minute, unit: ton / min

[0533] Step 6: According to the remaining casting time of 18.4 min obtained in Step 5 and the transportation time of 7 min required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process obtained in Step 3, calculate the current heat LF refining production time that meets the continuous casting production schedule according to Equation (5), that is:

[0534] Time _LF =Time _cast -Time _transport (5)

[0535] =18.4 - 7=11.4min

[0536] In the formula: Time_ LF ——The current heat LF refining production time, unit: min;

[0537] Time_ cast ——The remaining casting time of the corresponding heat of the current continuous casting machine, unit: min;

[0538] Time _transport ——The transportation time required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process, unit: min

[0539] Step 7: According to the molten steel temperature drop rate of 0.9℃ / min of the 5# ladle and the molten steel transportation time of 7 min corresponding to the 1CC continuous casting machine in Step 3, calculate the temperature loss Lost during transportation according to Equation (6) _Transport ;

[0540] Lost _Transport =Time _transport ·V 损失 (6)

[0541] =7×0.9=6.3℃

[0542] In the formula: Lost _Transport ——The temperature loss during transportation, unit: ℃;

[0543] Time_ transport ——The molten steel transportation time, unit: min;

[0544] V 损失 ——The molten steel temperature drop rate under different ladle conditions, unit: ℃ / min.

[0545] Combined with the target temperature of 1545 °C in the continuous casting tundish in Step 3, according to Equation (7), the target temperature that the molten steel needs to reach when leaving the LF refining station is calculated as follows:

[0546] Temp _LF_Out = Temp _tundish + Lost _Transport (7)

[0547] = 1545 + 6.3 = 1551.3 °C

[0548] In the formula: Temp _LF_Out ——The target temperature when leaving the LF refining station, unit: °C;

[0549] Temp _tundish ——The target temperature of the continuous casting tundish, unit: °C;

[0550] Lost _Transport ——The temperature loss during transportation, unit: °C;

[0551] Step 8: According to the LF refining production time obtained in Step 6 and the temperature drop rate of 0.9 °C / min of the molten steel in Ladle No. 5 in Step 3, calculate the temperature loss of the molten steel caused by the ladle condition during the LF refining process according to Equation (8):

[0552] Lost _LF = Time _LF ·V 损失 (8)

[0553] 11.4×0.9 = 10.26 °C

[0554] In the formula: Lost _LF ——The temperature loss caused by the ladle condition during the LF refining process, °C; Time _LF ——

[0555] The LF refining production time, min;

[0556] V 损失 ——The temperature drop rate of the molten steel under different ladle conditions, unit: °C / min

[0557] Step 9: According to the molten steel inlet temperature of 1525 °C in the LF refining in Step 3, the total temperature change of the molten steel caused by various materials of -11.25 °C, the LF refining outlet target temperature of 1551.3 °C in Step 7, and the temperature loss of 10.26 °C caused by the ladle condition in Step 8, calculate the total temperature that the molten steel needs to be raised according to Equation (9):

[0558] dT = K0·(Temp _LF_Out - T _Begin + Lost _LF+Lost _Mat ) (9)

[0559] = 1.08 × [1551.3 - 1525 + 10.26 - (-11.25)] = 48.7 °C

[0560] Where: dT - The total temperature to be raised for the molten steel, unit: °C;

[0561] K0 - The temperature rise threshold, with a value of 1.08;

[0562] Temp _LF—Out - The target temperature at the end of LF refining, unit: °C;

[0563] T _Begin - The temperature of the molten steel entering LF refining, unit: °C;

[0564] Lost _LF - The temperature loss caused by the ladle condition during LF refining, °C;

[0565] Lost _Mat - The total change in the temperature of the molten steel caused by various materials during LF refining, °C.

[0566] Step 10: Based on the total temperature of 48.7 °C to be raised for the molten steel obtained in Step 9 and the molten steel weight of 125 t in Step 3, calculate the additional heat required to reach the target temperature of the molten steel according to Equation (10):

[0567] Q = C · Steel _wt · dT (10)

[0568] = 460 × 125 × 48.7 = 2.79 × 10 6 KJ

[0569] Where: Q - The total required heat, unit: KJ;

[0570] C - The specific heat of molten steel, default value is 460 KJ / ton / K;

[0571] Steel _wt - The weight of molten steel, unit: ton;

[0572] dT - The total temperature to be raised for the molten steel, unit °C.

[0573] The heating time Time required for the molten steel _Hot is half of the total LF refining time, Time _Hot = 11.4 / 2 = 5.7 min

[0574] Based on the total heat T, the set average power supply P can be calculated according to Equation (11), that is:

[0575] P=3600·Q / (Time _Hot 60) / 1000 (11)

[0576] =(3600×2.79×10 6 / (5.7×60) / 1000)=2947kW

[0577] Where: P——set average power supply power, unit: kW;

[0578] Q——total calories required, unit: KJ;

[0579] Step 11: Based on the power supply parameters of the LF refined power supply equipment in step 1, calculate the arc useful work power Pi corresponding to all gear voltages and gear currents of the corresponding power supply equipment according to equations (12)-(14), that is:

[0580]

[0581]

[0582]

[0583] Where: U i ——The voltage of a certain gear of the power supply system, unit: V;

[0584] I i ——Current in a certain gear of the power supply system, unit: KA.

[0585] S i ——The power corresponding to a certain voltage and current, unit: kW;

[0586] Q i ——Reactive power corresponding to a certain voltage and current, unit: kW;

[0587] P i ——The useful work power corresponding to a certain gear voltage and current, unit: kW;

[0588] a1——Rated power of the corresponding power supply system, which is provided by the system, unit: kW;

[0589] b1——Rated voltage of the corresponding power supply system, which is provided by the system, unit: V;

[0590] c1——corresponding to the short-circuit impedance of the power supply system, which is built into the system. Unit: Ω.

[0591] For the power supply system corresponding to LF refining, calculate the useful power corresponding to the voltages and currents of all gears. Then, by comparing the set average power supply P with the arc useful power P i corresponding to the voltages and currents of all gears one by one, find the P i closest to P according to Equation (15). i The gear voltage and current corresponding to the P closest to 2947 kW are found by comparison.

[0592] min(|P - P i |) (15)

[0593] Step 12: Display the calculated production time of 11.4 min, power supply voltage of 390 V, and power supply current of 9.2 kA for the current heat of LF refining on the screen to guide on-site production.

[0594] Step 13: The computer continues to read the LF refining level-1 PLC data in real time. When it detects that the ladle cover signal is False and the bottom blowing argon flow data is 0 L / min, it indicates that LF refining has stopped production. At this time, the computer clears the results and prepares for the calculation of the next heat.

[0595] Step 14: Repeat the operations in Step 2 to Step 12 to achieve the tracking calculation of the production time, power supply voltage, and power supply current results for different heats during the LF refining production process.

Claims

1. A method for intelligently analyzing the production time and power supply parameters of LF refining, characterized in that: First, install a computer at the LF refining site, connect the computer to the first-level PLC, the second-level material calculation system, and the third-level MES data network, and install a model for intelligently analyzing the production time and power supply parameters of LF refining in the computer. Proceed as follows: Step 1: Enter basic information into the computer, including: the transportation time correspondence table from LF refining to the continuous casting machine, the molten steel temperature drop rate table for different ladle conditions, the molten steel temperature change table caused by the addition of different materials, the LF refining power supply system parameters, and the search range table for step voltage and step current based on the characteristics of the power supply system. The transportation time correspondence table is the correspondence table between the continuous casting machine number and the corresponding transportation time. When a specific continuous casting machine number is input into the computer, the computer can, according to the correspondence in the table, feedback the corresponding transportation time. The molten steel temperature drop rate table for different ladle conditions is the correspondence table between the ladle code and the corresponding molten steel temperature drop rate. When a specific ladle condition code is input into the computer, the computer can, according to the correspondence in the table, feedback the corresponding molten steel temperature drop rate. The molten steel temperature change table caused by the addition of different materials is the correspondence table between each material and the corresponding temperature change coefficient. When a specific material name is input into the computer, the computer can, according to the correspondence in the table, calculate the corresponding temperature change value. Step 2: The computer determines whether LF refining is in the production state by detecting the ladle capping signal. If so, proceed to Step 3. Step 3: The computer reads the following data from the third-level MES system: The current LF refining production plan, including the weight, temperature, and ladle condition of the molten steel entering the station, and the temperature drop rate obtained therefrom; the subsequent continuous casting machine casting plan information, including the continuous casting machine number and transportation time, the tundish target temperature, the slab cross-sectional area, the molten steel density, the empty ladle weight of the tundish, and the remaining molten steel weight of the tundish required by the process control. The computer reads the information on the weight of bulk materials and alloys to be added in LF refining from the second-level material calculation system, and according to the molten steel temperature change table caused by the addition of different materials in Step 1, calculates the molten steel temperature change caused by the addition of materials according to Equation (1): Lost _Mat_i = Mat _i · T _drop_i (1) In the formula: Lost_Mat_i—the molten steel temperature change caused by the addition of materials, unit: °C; Mat_i—the amount of material added, unit: ton; T_drop_i—the temperature change coefficient caused by the material, unit: °C / ton. Sum up the molten steel temperature changes caused by various materials, and calculate the total temperature change caused by the addition of materials according to Equation (2): Where: Lost _Mat —— The total change in molten steel temperature caused by various materials, unit: °C; Lost _Mat_i —— Temperature change caused by various feedings, unit: °C. Step 4: The computer reads the casting speed of the continuous casting machine corresponding to the production plan in the first-level PLC at the current moment, combines the slab cross-sectional area and molten steel density data obtained in Step 3, and calculates the weight of molten steel that can be poured out per minute according to Equation (3), that is: Wt_ cast = S · Dens · V (3) In the formula: Wt_cast—the weight of molten steel that can be poured out per minute, unit: ton / min; S—— cross-sectional area of the slab, unit: m 2 ; Dens - Molten steel density ton / m 3 ; V—the casting speed of the continuous casting machine, unit: m / min. Step 5: The computer reads the weighing weight data of the continuous casting ladle turntable in the first-level PLC at the current moment once, combines the empty ladle weight obtained in Step 3 and the remaining steel weight of the ladle required by the process control requirements, combines the weight of molten steel that can be poured out per minute in Step 4, and calculates the remaining casting time according to Equation (4), that is: Time _cast = (Wt - Wt _GB - Wt _Last ) / Wt _cast (4) In the formula: Time_cast - The remaining casting time for the corresponding heat of the current continuous casting machine, unit: min; Wt - The weighing weight of the current ladle turntable, unit: ton; Wt_GB - The empty ladle weight of the current ladle, unit: ton; Wt_Last - The remaining steel weight of the ladle, unit: ton; Wt_cast - The weight of molten steel that can be poured out per minute, unit: ton / min Step 6: According to the remaining casting time obtained in Step 5 and the transportation time required for the molten steel to be transported from the LF refining process to the corresponding continuous casting process obtained in Step 3, calculate the LF refining production time of the current heat that meets the continuous casting production schedule according to Equation (5), that is: Time _LF = Time _cast -Time _transport (5) Where: Time_ LF —— The LF refining production time of the current heat, unit: min; Time_ cast —— Remaining steel casting time for the corresponding heat of the current continuous caster, unit: min; Time _transport —— The time required for transporting molten steel from the LF refining process to the corresponding continuous casting process, unit: min Step 7: According to the molten steel temperature drop rate and molten steel transportation time under different ladle conditions in Step 3, calculate the temperature loss Lost during transportation according to Equation (6). _Transport ; Lost _Transport = Time _transport ·V 损失 (6) Where: Lost _Transport —— Temperature loss during transportation, unit: °C; Time_ transport ——Transportation time of molten steel, unit: min; V 损失 ——The temperature drop rate of molten steel under different ladle conditions, unit: °C / min. Furthermore, combined with the target temperature of the continuous casting tundish in Step 3, the temperature that the molten steel needs to reach when leaving the LF refining station is calculated according to Equation (7): Temp _LF_Out＝ Temp _tundish +Lost _Transport (7) In the formula: Temp _LF_Out —— Target temperature at the end of LF refining, unit: °C; Temp _tundish ——Target temperature of the continuous casting tundish, unit: °C; Lost _Transport ——Temperature loss during transportation, unit: °C; Step 8: Calculate the temperature loss of the molten steel caused by the ladle condition during the LF refining process according to Equation (8): Lost _LF = Time _LF ·V 损失 (8) Where: Lost _LF —— Temperature loss caused by ladle condition during LF refining process, °C; Time _LF ——LF refining production time, min; V 损失 ——Rate of temperature drop of molten steel under different ladle conditions, unit: °C / min Step 9: According to the incoming temperature of the molten steel in the LF refining process in Step 3, the total change in the temperature of the molten steel caused by various materials, the target temperature when leaving the LF refining station in Step 7, and the temperature loss caused by the ladle condition in Step 8, calculate the total temperature that the molten steel needs to be raised according to Equation (9): dT = K0·(Temp _LF_Out - T _Begin + Lost _LF + Lost _Mat )(9) In the formula: dT - The total temperature that the molten steel needs to be raised, unit: °C; K0 - The heating threshold, with a value of 1.0 - 1.2; Temp _LF—Out ——Target temperature at the end of LF refining, unit: °C; T _Begin ——The tapping temperature of molten steel for LF refining, unit: °C; Lost _LF —— Temperature loss caused by ladle condition during LF refining, °C; Lost _Mat ——Total temperature change of molten steel caused by various materials during LF refining process, °C. Step 10: From the total temperature that the molten steel needs to be raised obtained in Step 9 and the weight of the molten steel in Step 3, calculate the additional heat required to reach the target temperature of the molten steel according to Equation (10): Q = C · Steel _wt · dT (10) In the formula: Q - The total required heat, unit: KJ; C - The specific heat of molten steel, default value is 460 KJ / ton / K; Steel _wt —— Weight of molten steel, unit: ton; dT - The total temperature that the molten steel needs to be raised, unit °C. The set average power supply P can be calculated from the total heat T according to Equation (11), that is: P = 3600 · Q / (Time _Hot · 60) / 1000 (11) In the formula: P - The set average power supply, unit: kW; Q - The total required heat, unit: KJ; Time _Hot —— Heating time required for molten steel, unit: min. Time _Hot is half of the total LF refining time, i.e., Time _Hot = Time _LF / 2 Step 11: According to the power supply parameters of the LF refining power supply equipment in Step 1, calculate the useful arc power Pi corresponding to the voltages and currents of all gears under the corresponding power supply equipment according to Formulas (12)-(14), i.e.: Where: U i —— The voltage of a certain gear in the power supply system, unit: V; I i —— Current of a certain gear in the power supply system, unit: KA. S i ——The characteristic power corresponding to a certain gear voltage and current, unit: kW; Q i ——Reactive power corresponding to a certain gear voltage and current, unit: kW; P i —— The useful power corresponding to a certain gear voltage and current, unit: kW; a1 - The rated power of the corresponding power supply system, provided by the system, unit: kW; b1 - The rated voltage of the corresponding power supply system, provided by the system, unit: V; c1 - The short-circuit impedance of the corresponding power supply system, provided by the system, unit: Ω. For the power supply system corresponding to LF refining, calculate the useful power corresponding to the voltages and currents of all gears. Then, by comparing the set average power supply P with the useful arc power P i corresponding to the voltages and currents of all gears one by one, find the P i closest to P according to Equation (15), and the corresponding gear voltages and currents are: min(|P - P i |) (15) Step 12: Reflect the calculated production time of the current heat of LF refining, the power supply voltage, and the power supply current results on the computer screen for guiding on-site production. Step 13: The computer continues to read the LF refining first-level PLC data in real time. When it detects that the LF refining is in a shutdown state, the computer clears the production time of the current heat of LF refining, the power supply voltage, and the power supply current results obtained in Step 12. Step 14: Repeat the operations of Step 2 to Step 12 to achieve the tracking calculation of the production time, power supply voltage, and power supply current results of different heats during LF refining production.

2. The method for intelligently analyzing the production time and power supply parameters of LF refining according to claim 1, characterized in that: The parameters of the LF refining power supply system include rated power, rated voltage, and short-circuit impedance.

3. The method for intelligently analyzing the production time and power supply parameters of LF refining according to claim 1, characterized in that: In Step 2, the computer determines whether LF refining is in the production state by detecting the ladle cover signal. Specifically, when the ladle cover signal at the current station is detected as Ture and the bottom blowing argon flow rate data is greater than 0 L / min, it indicates that LF refining is in the production state; in Step 13, when the ladle cover signal at the current station is detected as False and the bottom blowing argon flow rate data is equal to 0 L / min, it indicates that LF refining is in the shutdown state.

4. The method for intelligently analyzing the production time and power supply parameters of LF refining according to claim 1, characterized in that: The model installed in the computer for intelligent analysis of the production time and power supply parameters of LF refining is an artificial intelligence model written in the python programming language.

5. The method for intelligently analyzing the production time and power supply parameters of LF refining according to claim 1, wherein: The computer uses the Modbus protocol for communication with the first-level PLCs at the LF refining site and the continuous casting site; the computer uses the Oracle database protocol for communication with the on-site second-level material calculation system and the third-level MES system.

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