Module superheat degree control method

Abstract

The invention discloses a module superheat degree control method which comprises the following steps: (1) carrying out big data fitting analysis on the superheat degree to obtain a control function of superheat degree control of a turnover steel ladle: the superheat degree is equal to 13.467 + 0.01901 T vacuum + 0.26687 T crane ladle-0.03262 t empty ladle, T vacuum is vacuum inlet temperature, T crane ladle is crane ladle temperature, and t empty ladle is empty ladle time; and (2) on the basis of the functions, the steel ladles are divided into turnover steel ladles, non-turnover steel ladles, new steel ladles, slag changing lines or minor repair steel ladles, and different temperature control modules and corresponding parameters are respectively formed by considering steel types. The method has the advantages that the superheat degree is kept between 20 DEG C and 30 DEG C, the molten steel temperature is stabilized, the temperature fluctuation range is reduced, and the product quality is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of iron and steel metallurgy, and particularly relates to a method for controlling the superheat of a module. Background Art

[0002] Stable superheat and good temperature uniformity are key factors to ensure the production efficiency of steelmaking - continuous casting and the stability of the quality of the cast slab. In modern continuous casting production practice, the tundish is not only a container for storing molten steel, but also a crucial device for controlling the composition, temperature, and cleanliness of molten steel. Usually, in order to ensure the smooth progress of the continuous casting process and the quality of the cast slab, the temperature of the molten steel in the tundish must be accurately controlled. During the continuous casting process, due to factors such as the heat absorption of the refractory lining in the tundish, the radiation heat dissipation during the pouring process of molten steel, and the lack of supply of high-temperature molten steel in the tundish at the end of ladle change and pouring, the temperature drop of molten steel is severe and the fluctuation range of superheat is relatively large.

[0003] The change in the temperature of the molten steel in the tundish affects the quality of the continuous casting slab and thus the quality of the product steel. Excessive temperature of the molten steel will increase the economic cost of steelmaking, and a relatively high superheat is also not conducive to the growth of equiaxed crystals; too low temperature of the molten steel will greatly increase the probability of accidents such as nodulation, freezing, reverting to the furnace, and stopping pouring in the tundish. Therefore, seeking an external heat source to compensate for the temperature drop of the molten steel in the tundish and keeping the pouring temperature of the molten steel near the target value has become a hot issue of current concern. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of severe temperature drop of molten steel in the existing tundish and large fluctuation range of superheat, and provides a method for controlling the superheat of a module, which can keep the superheat between 20 - 30 °C, stabilize the temperature of molten steel, reduce the temperature fluctuation range, and improve the product quality while reducing costs.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions: A method for controlling the superheat of a module, the specific steps are as follows, including: (1) Conduct a big data fitting analysis on the superheat, and obtain the control function for controlling the superheat of the turnover ladle as: superheat = 13.467 + 0.01901 T 真空 + 0.26687 T 吊包 - 0.03262 t 空包 , where T 真空 is the temperature entering the vacuum, T 吊包 is the ladle hanging temperature, and t 空包 is the empty ladle time; (2) On the basis of the above function, divide the ladles into turnover ladles, non-turnover ladles, new ladles, ladles for slag line change or minor repair, and consider the steel grades to form different temperature control modules respectively; (3)For non-turnover ladles, new ladles, ladles for slag change line or minor repair, the control situations are divided into four categories, namely: superheat difference with soaking time ≤ 180 min, superheat difference with soaking time 181 - 240 min, superheat difference with soaking time 241 - 300 min, and superheat difference with soaking time > 300 min; (4)According to the above four control situations, the inlet vacuum temperatures of non-turnover ladles are set as 140 - 150 °C, 145 - 152 °C, 140 - 148 °C, 144 - 150 °C in sequence, and the continuous casting inlet temperatures of non-turnover ladles are set as 61 - 67 °C, 55 - 65 °C, 55 - 65 °C, 53 - 59 °C in sequence; (5)According to the above four control situations, the inlet vacuum temperatures of new ladles are set as 148 - 153 °C, 145 - 150 °C, 145 - 150 °C, 145 - 150 °C in sequence, and the continuous casting inlet temperatures of new ladles are set as 63 - 68 °C, 60 - 65 °C, 62 - 67 °C, 60 - 65 °C in sequence; (6)According to the above four control situations, the inlet vacuum temperatures of ladles for slag change line or minor repair are set as 140 - 147 °C, 147 - 153 °C, 145 - 150 °C, 148 - 153 °C in sequence, and the continuous casting inlet temperatures of ladles for slag change line or minor repair are set as 60 - 64 °C, 58 - 63 °C, 55 - 60 °C, 55 - 60 °C in sequence.

[0006] Further, in the step (2), for different steel grades, including low-carbon steel, medium-carbon steel and high-carbon steel, the control situations are divided into five categories, namely: superheat difference with empty ladle time ≤ 240 min, superheat difference with soaking time ≤ 180 min, superheat difference with soaking time 181 - 240 min, superheat difference with soaking time 241 - 300 min, and superheat difference with soaking time > 300 min.

[0007] Further, according to the above five control situations, the inlet vacuum temperatures of low-carbon steel are set as 138 - 143 °C, 133 - 138 °C, 140 - 146 °C, 137 - 142 °C, 137 - 142 °C in sequence, and the continuous casting inlet temperatures of low-carbon steel are set as 57 - 63 °C, 60 - 65 °C, 55 - 60 °C, 55 - 60 °C, 53 - 58 °C in sequence.

[0008] Further, according to the above five control situations, the inlet vacuum temperatures of medium-carbon steel are set as 145 - 150 °C, 140 - 144 °C, 149 - 153 °C, 150 - 155 °C, 145 - 150 °C in sequence, and the continuous casting inlet temperatures of medium-carbon steel are set as 57 - 63 °C, 58 - 62 °C, 57 - 61 °C, 55 - 60 °C, 55 - 60 °C in sequence.

[0009] Furthermore, according to the above five control cases, the vacuum inlet temperatures of high-carbon steel are set to 139 - 141 °C, 134 - 139 °C, 138 - 143 °C, 137 - 143 °C, and 135 - 140 °C in sequence, and the continuous casting upper temperatures of high-carbon steel are set to 55 - 60 °C, 55 - 60 °C, 55 - 60 °C, 55 - 60 °C, and 55 - 60 °C in sequence.

[0010] In the technical solution of the present invention, through big data analysis and combined with the actual on-site situation, a modular superheat control method is designed, which can achieve superheat control within 20 - 30 °C with a qualification rate of 100%, greatly improving the quality of steel billets. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is the superheat residual graph obtained by big data fitting analysis of the superheat in the present invention; Figure 2 It is the parameter table of the superheat control module of the present invention; Figure 3 It is the macrostructure diagram of the steel billet after treatment in the first embodiment; Figure 4 It is the macrostructure diagram of the steel billet after treatment in the second embodiment; Figure 5 It is the macrostructure diagram of the steel billet after treatment in the third embodiment. SPECIFIC EMBODIMENTS Embodiment 1

[0012] To make the present invention more clearly understood, the following further illustrates a modular superheat control method of the present invention with reference to the accompanying drawings. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0013] A modular superheat control method, characterized in that: (1) Referring to Figure 1 , through big data fitting analysis of the superheat, the control function for the superheat control of the turnover ladle is obtained as: superheat = 13.467 + 0.01901 T 真空 + 0.26687 T 吊包 - 0.03262 t 空包 , where T 真空 is the vacuum inlet temperature, T 吊包 is the ladle hanging temperature, and t 空包 is the empty ladle time; (2) Based on the above function, the ladles are divided into turnover ladles, non-turnover ladles, new ladles, ladles for slag line change or minor repair, and considering the steel grades, different temperature control modules are formed respectively. Refer to Figure 2 .

[0014] In this embodiment, the steel grade ER69A, a low-carbon steel, is taken as an example. The ladle is a reusable ladle, with a liquidus temperature of 1513°C, an empty ladle time of 180 minutes, a temperature entering the vacuum of 140°C, a ladle hanging temperature of 60°C, and a final superheat of 27°C. The macrostructure is as Figure 3 shown. Example 2

[0015] In this embodiment, the steel grade S55C-SV is taken as an example. The liquidus temperature is 1483°C, the ladle is a non-reusable ladle, the soaking time is 220 minutes, the temperature entering the vacuum is 144°C, the temperature for continuous casting is 60°C, and the superheat is 27°C. The macrostructure is as Figure 4 shown. Example 3

[0016] In this embodiment, the steel grade GCr15 is taken as an example. The liquidus temperature is 1450°C, the soaking time is 362 minutes, the temperature entering the vacuum is 138°C, the temperature for continuous casting is 58°C, and the superheat is 24°C. The macrostructure is as Figure 5 shown.

[0017] In addition to the above embodiments, the present invention may have other implementation manners. Any technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A method for controlling the superheat degree of a module, characterized in that: (1) Conduct big data fitting analysis on the superheat degree, and obtain the control function for controlling the superheat degree of the turnover ladle as: Superheat degree = 13.467 + 0.01901 T 真空 + 0.26687 T 吊包 - 0.03262 t 空包 , where T 真空 is the temperature entering the vacuum, T 吊包 is the ladle hanging temperature, and t 空包 is the empty ladle time; (2) Based on the above function, the ladle is divided into a turnover ladle, a non-turnover ladle, a new ladle, a slag-changing line or a minor repair ladle, and different temperature control modules are formed respectively considering the steel grade. (3) For non-turnover ladles, new ladles and slag-changing line or minor repair ladles, the control situations are divided into four categories, namely: superheat degree difference when the soaking time ≤ 180 min, superheat degree difference when the soaking time is 181 - 240 min, superheat degree difference when the soaking time is 241 - 300 min, and superheat degree difference when the soaking time > 300 min. (4) According to the above four control situations, the vacuum inlet temperature of the non-turnover ladle is set to 140 - 150 °C, 145 - 152 °C, 140 - 148 °C, 144 - 150 °C in sequence, and the continuous casting upper temperature of the non-turnover ladle is set to 61 - 67 °C, 55 - 65 °C, 55 - 65 °C, 53 - 59 °C in sequence. (5) According to the above four control situations, the vacuum inlet temperature of the new ladle is set to 148 - 153 °C, 145 - 150 °C, 145 - 150 °C, 145 - 150 °C in sequence, and the continuous casting upper temperature of the new ladle is set to 63 - 68 °C, 60 - 65 °C, 62 - 67 °C, 60 - 65 °C in sequence. (6) According to the above four control situations, the vacuum inlet temperature of the slag-changing line or minor repair ladle is set to 140 - 147 °C, 147 - 153 °C, 145 - 150 °C, 148 - 153 °C in sequence, and the continuous casting upper temperature of the slag-changing line or minor repair ladle is set to 60 - 64 °C, 58 - 63 °C, 55 - 60 °C, 55 - 60 °C in sequence.

2. The method for controlling the superheat degree of a module according to claim 1, characterized in that: In the step (2), for different steel grades, including low-carbon steel, medium-carbon steel and high-carbon steel, the control situations are divided into five categories, namely: superheat degree difference when the empty ladle time ≤ 240 min, superheat degree difference when the soaking time ≤ 180 min, superheat degree difference when the soaking time is 181 - 240 min, superheat degree difference when the soaking time is 241 - 300 min, and superheat degree difference when the soaking time > 300 min.

3. The method for controlling the superheat degree of a module according to claim 2, characterized in that: According to the above five control situations, the vacuum inlet temperature of low-carbon steel is set to 138 - 143 °C, 133 - 138 °C, 140 - 146 °C, 137 - 142 °C, 137 - 142 °C in sequence, and the continuous casting upper temperature of low-carbon steel is set to 57 - 63 °C, 60 - 65 °C, 55 - 60 °C, 55 - 60 °C, 53 - 58 °C in sequence.

4. The method for controlling the superheat degree of a module according to claim 2, characterized in that: According to the above five control situations, the vacuum inlet temperature of medium-carbon steel is set to 145 - 150 °C, 140 - 144 °C, 149 - 153 °C, 150 - 155 °C, 145 - 150 °C in sequence, and the continuous casting upper temperature of medium-carbon steel is set to 57 - 63 °C, 58 - 62 °C, 57 - 61 °C, 55 - 60 °C, 55 - 60 °C in sequence.

5. The method for controlling the superheat degree of a module according to claim 2, characterized in that: According to the above five control cases, the vacuum inlet temperatures of high-carbon steel are set to 139 - 141 °C, 134 - 139 °C, 138 - 143 °C, 137 - 143 °C, and 135 - 140 °C in sequence, and the continuous casting upper temperatures of high-carbon steel are set to 55 - 60 °C, 55 - 60 °C, 55 - 60 °C, 55 - 60 °C, and 55 - 60 °C in sequence.

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