Method and system for matching the rotational speed and immersion depth of a kr machine

Abstract

The application discloses a method and system for matching KR mechanical stirring speed and immersion depth, comprising: obtaining the current KR mechanical stirring process ladle geometric size and stirring paddle geometric size, and the initial liquid level of molten iron; predicting the KR mechanical stirring process molten iron multiphase flow field under different stirring paddle speed and immersion depth; obtaining the critical speed affected by the stirring paddle immersion depth; obtaining the stirring paddle speed and immersion depth and the change relationship formula of the molten iron multiphase flow field; obtaining the KR mechanical stirring vortex shape size and the change relationship formula of the molten iron multiphase flow field through the output KR mechanical stirring vortex shape size; and calculating the critical value of the stirring paddle speed and immersion depth when the KR mechanical stirring vortex lowest point reaches the top of the stirring paddle. The technical scheme of the application can quantitatively obtain the critical speed and immersion depth value for improving the stirring efficiency, can provide scientific guidance for the field production, can improve the desulfurizer dispersion degree and reduce the desulfurization period, and can optimize the production practice.

Description

Technical Field

[0001] This invention belongs to the field of steelmaking technology in the metallurgical industry, and particularly relates to a method and system for matching the KR mechanical stirring speed and immersion depth. Background Technology

[0002] The KR mechanical stirring method is widely used in the desulfurization process of molten iron pretreatment in steelmaking. Although the KR mechanical stirring desulfurization process has many advantages, such as good desulfurization kinetics and high desulfurization efficiency, there is still room for optimization. In particular, the high proportion of dead zones in the flow field below the molten iron ladle and the low dispersion caused by the accumulation of desulfurizing agent at the bottom of the stirring vortex lead to a decrease in the desulfurization rate and the actual utilization rate of the desulfurizing agent. Simultaneously, it also adversely affects iron loss and the temperature drop of the treatment process. Studies have shown that the proportion of dead zones in the molten iron ladle and the degree of desulfurizing agent accumulation in the stirring vortex are directly related to the stirring paddle speed and immersion depth. An improperly matched stirring paddle speed and immersion depth will lead to a significant increase in the proportion of dead zones and the degree of desulfurizing agent accumulation. Determining the minimum critical speed for reducing the proportion of dead zones and the degree of desulfurizing agent accumulation at different immersion depths, i.e., achieving a reasonable match between stirring paddle speed and immersion depth, is crucial for further improving desulfurization efficiency, reducing desulfurizing agent consumption, and shortening the desulfurization cycle. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method and system for matching the stirring speed and immersion depth of KR mechanical stirring, which can quantitatively obtain the critical speed and immersion depth values ​​for improving stirring efficiency, and achieve the matching of stirring speed and immersion depth for the purpose of improving the dispersion of desulfurizing agent and reducing desulfurization cycle.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for matching KR mechanical stirring speed and immersion depth includes:

[0006] Step S1: Obtain the current geometric dimensions of the ladle and the agitator in the KR mechanical stirring process, as well as the initial liquid level of the molten iron;

[0007] Step S2: Based on the current geometric dimensions of the ladle and the agitator in the KR mechanical stirring process, as well as the initial liquid level of the molten iron, predict the multiphase flow field of the molten iron in the KR mechanical stirring process under different agitator speeds and immersion depths.

[0008] Step S3: Based on the multiphase flow field of molten iron, obtain the critical rotational speed that affects the immersion depth of the stirring paddle;

[0009] Step S4: Determine the relationship between the stirring paddle speed and immersion depth and the multiphase flow field of molten iron;

[0010] Step S5: Determine the relationship between the shape and size of the KR mechanical stirring vortex and the change of the multiphase flow field of molten iron based on the shape and size of the KR mechanical stirring vortex.

[0011] Step S6: Based on the relationship between the shape and size of the KR mechanical stirring vortex and the multiphase flow field of molten iron, obtain the critical values ​​of the rotational speed and immersion depth at which the lowest point of the KR mechanical stirring vortex reaches the top of the stirring paddle.

[0012] As a preferred option, the relationship between the stirring paddle rotation speed and immersion depth and the multiphase flow field of molten iron is obtained as follows:

[0013]

[0014] Where C1 and C2 are constants; ε is the turbulent kinetic energy dissipation rate; h id n is the immersion depth; n is the rotational speed; n id The critical rotational speed that affects the effect of the impeller immersion depth on the multiphase flow field of molten iron.

[0015] As a preferred option, the relationship between the shape and size of the KR mechanical stirring vortex and the change in the multiphase flow field of molten iron is obtained as follows:

[0016] ΔH d =C3·ε 0.67

[0017] Where C3 is a constant; ΔH d ΔH represents the vortex depth. h ε is the vortex height; ε is the turbulent kinetic energy dissipation rate.

[0018] As a preferred embodiment, the relationship between the critical rotational speed at which the lowest point of the KR mechanical stirring vortex reaches the top of the impeller and the critical immersion depth is as follows:

[0019]

[0020] Where C4 is a constant; n cr The critical speed; h cr This represents the critical immersion depth.

[0021] The present invention also provides a system for matching the KR mechanical stirring speed and immersion depth, comprising:

[0022] The first processing module is used to obtain the geometric dimensions of the ladle and the agitator in the current KR mechanical stirring process, as well as the initial liquid level of the molten iron.

[0023] The second processing module is used to predict the multiphase flow field of molten iron in the KR mechanical stirring process under different stirring speeds and immersion depths, based on the current geometric dimensions of the ladle and stirring paddle in the KR mechanical stirring process, as well as the initial liquid level of the molten iron.

[0024] The third processing module is used to obtain the critical rotational speed that affects the immersion depth of the stirring paddle based on the multiphase flow field of molten iron.

[0025] The fourth processing module is used to determine the relationship between the stirring paddle speed and immersion depth and the multiphase flow field of molten iron.

[0026] The fifth processing module is used to determine the relationship between the shape and size of the KR mechanical stirring vortex and the change of the multiphase flow field of molten iron based on the shape and size of the KR mechanical stirring vortex.

[0027] The sixth processing module is used to obtain the critical values ​​of the rotational speed and immersion depth at which the lowest point of the KR mechanical stirring vortex reaches the top of the stirring paddle, based on the relationship between the shape and size of the KR mechanical stirring vortex and the multiphase flow field of molten iron.

[0028] As a preferred option, the relationship between the stirring paddle rotation speed and immersion depth and the multiphase flow field of molten iron is obtained as follows:

[0029]

[0030] Where C1 and C2 are constants; ε is the turbulent kinetic energy dissipation rate; h id n is the immersion depth; n is the rotational speed; n id The critical rotational speed that affects the effect of the impeller immersion depth on the multiphase flow field of molten iron.

[0031] As a preferred option, the relationship between the shape and size of the KR mechanical stirring vortex and the change in the multiphase flow field of molten iron is obtained as follows:

[0032] ΔH d =C3·ε 0.67

[0033] Where C3 is a constant; ΔH d ΔH represents the vortex depth. h ε is the vortex height; ε is the turbulent kinetic energy dissipation rate.

[0034] As a preferred embodiment, the relationship between the critical rotational speed at which the lowest point of the KR mechanical stirring vortex reaches the top of the impeller and the critical immersion depth is as follows:

[0035]

[0036] Where C4 is a constant; n cr The critical speed; h cr This represents the critical immersion depth.

[0037] This invention obtains the geometric dimensions of the ladle and impeller in the current KR mechanical stirring process, as well as the initial molten iron level. Based on the obtained parameters, it predicts the multiphase flow field of the molten iron under different impeller speeds and immersion depths. By comparing the multiphase flow fields, it obtains the critical speed affecting the impeller immersion depth. Based on the above parameters, it obtains the relationship between the impeller speed and immersion depth and the multiphase flow field of the molten iron. By outputting the shape and size of the KR mechanical stirring vortex, it obtains the relationship between the shape and size of the KR mechanical stirring vortex and the multiphase flow field of the molten iron. Based on the obtained relationships, it calculates the critical speed and immersion depth values ​​at which the lowest point of the KR mechanical stirring vortex reaches the top of the impeller. This invention can quantitatively obtain the critical speed and immersion depth values ​​for improving stirring efficiency, providing scientific guidance for on-site production, improving the dispersion of desulfurizing agents, reducing desulfurization cycles, and optimizing production practices. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0039] Figure 1 This is a flowchart illustrating the method for matching the KR mechanical stirring speed and immersion depth according to an embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram illustrating the variation of the turbulent kinetic energy dissipation rate of molten iron with rotational speed and immersion depth in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram illustrating the variation of vortex depth with turbulent kinetic energy dissipation rate in an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram illustrating the changes in critical stirring speed and immersion depth in an embodiment of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] Example 1:

[0046] like Figure 1 As shown, this embodiment of the invention provides a method for matching the KR mechanical stirring speed and immersion depth, including:

[0047] Step S1: Obtain the current geometric dimensions of the ladle and the agitator in the KR mechanical stirring process, as well as the initial liquid level of the molten iron;

[0048] Step S2: Based on the current geometric dimensions of the ladle and the impeller in the KR mechanical stirring process, as well as the initial liquid level of the molten iron, establish a three-dimensional calculation domain for the KR mechanical stirring process. Further, use the VOF air-molten iron multiphase model and the k-ε flow model to numerically calculate the multiphase flow field distribution and vortex shape and size of the molten iron in the KR mechanical stirring process under different impeller speeds and immersion depths.

[0049] Step S3: Based on the multiphase flow field of molten iron, obtain the critical rotational speed that affects the immersion depth of the stirring paddle;

[0050] Step S4: Determine the relationship between the stirring paddle speed and immersion depth and the multiphase flow field of molten iron;

[0051] Step S5: Compare the calculated multiphase flow field distribution and vortex shape and size at different stirring impellers and immersion depths, and fit the relationship between the KR mechanical stirring vortex shape and size and the multiphase flow field of molten iron.

[0052] Step S6: Based on the relationship between the shape and size of the KR mechanical stirring vortex and the multiphase flow field of molten iron, obtain the critical values ​​of the rotational speed and immersion depth at which the lowest point of the KR mechanical stirring vortex reaches the top of the stirring paddle.

[0053] As one embodiment of the present invention, step S3 specifically includes:

[0054] The stirring paddle immersion depth was set to the minimum value, the stirring paddle speed was changed, and the multiphase flow field distribution of the first molten iron was calculated.

[0055] The stirring paddle immersion depth was set to the maximum value, the stirring paddle speed was changed, and the distribution of the second molten iron multiphase flow field was calculated.

[0056] Based on the distribution of the first and second multiphase flow fields of molten iron, the critical rotational speed n that affects the influence of the impeller immersion depth on the multiphase flow field of molten iron is determined. id .

[0057] In one embodiment of the present invention, in step S4, the relationship between the stirring paddle rotation speed and immersion depth and the multiphase flow field of molten iron is obtained as follows:

[0058]

[0059] Where C1 and C2 are constants; ε is the turbulent kinetic energy dissipation rate; h id n is the immersion depth; n is the rotational speed; n id The critical rotational speed that affects the effect of the impeller immersion depth on the multiphase flow field of molten iron.

[0060] In one embodiment of the present invention, in step S5, the relationship between the shape and size of the KR mechanical stirring vortex and the change in the multiphase flow field of molten iron is obtained as follows:

[0061] ΔH d =C3·ε 0.67

[0062] Where C3 is a constant; ΔH d ε represents the vortex depth; ε represents the turbulent kinetic energy dissipation rate.

[0063] In one embodiment of the present invention, in step S6, the relationship between the stirring paddle speed and immersion depth and the multiphase flow field of molten iron in step S4 is expressed as ε=C2·n. 3 The relationship between the shape and size of the KR mechanical stirring vortex and the change in the multiphase flow field of molten iron in step S5 is expressed as ΔH. d =C3·ε 0.67 The relationship between the depth of the KR mechanical stirring vortex and the rotational speed is obtained as follows:

[0064] ΔH d =C4·n 2

[0065] When the lowest point of the KR mechanical stirring vortex reaches the top of the impeller, the vortex depth is equal to the immersion depth minus the impeller height of 950. Further, the relationship between the critical rotational speed and the critical immersion depth is obtained as follows:

[0066]

[0067] Where C4 is a constant; n cr The critical speed; h cr This represents the critical immersion depth.

[0068] This embodiment of the invention targets a ladle capacity of 230 tons and an initial molten iron height of 3601 mm. The top and bottom diameters of the ladle are 3869 mm and 3248 mm, respectively. The stirring paddle rotation radius is 727 mm. The entire computational domain is divided into approximately 530,000 structured mesh elements, with a fine gradient mesh used near the molten iron and slag interface. Table 1 summarizes other detailed parameters used in this study. The physical properties of the molten iron and air phases are shown in Table 1. By obtaining the current ladle and stirring paddle geometry, as well as the initial molten iron level, the multiphase flow field of the molten iron in the KR mechanical stirring process is predicted at different stirring paddle rotation speeds and immersion depths. Figure 2 As shown, based on the minimum and maximum immersion depth of the agitator (1400 mm and 1800 mm), the critical rotational speed n affecting the immersion depth of the agitator is determined. id It is 90 rpm. For example... Figure 3 As shown, the relationship between the stirring paddle speed and immersion depth and the multiphase flow field of molten iron is further determined, where C1 and C2 are 6.62 × 10⁻⁶. -10 and 7.36×10 --7 By outputting the shape and size of the KR mechanical stirring vortex, the relationship between the shape and size of the KR mechanical stirring vortex and the multiphase flow field of molten iron was determined, with C3 being 1.68. Further calculations yielded the relationship between the critical rotational speed and critical immersion depth at which the lowest point of the KR mechanical stirring vortex reaches the top of the impeller, with C4 being 0.130. (The last sentence appears to be incomplete and possibly refers to a different calculation.) Figure 4 As shown, the critical speeds for the stirring paddle at immersion depths of 1400mm, 1600mm, and 1800mm are 58.8rpm, 70.7rpm, and 80.9rpm, respectively.

[0069] Table 1

[0070]

[0071] This invention calculates the combined effects of parameters such as impeller rotation speed and immersion depth on the multiphase flow field distribution of molten iron and the shape and size of the KR mechanical stirring vortex during the KR mechanical stirring process. Based on the judgment criteria of this invention, the impeller rotation speed and immersion depth can be rationally matched according to actual production conditions, thereby providing scientific guidance for on-site production, improving the dispersion of desulfurizing agents, reducing the desulfurization cycle, and optimizing production practices.

[0072] Example 2:

[0073] This invention also provides a system for matching the KR mechanical stirring speed and immersion depth, comprising:

[0074] The first processing module is used to obtain the geometric dimensions of the ladle and the agitator in the current KR mechanical stirring process, as well as the initial liquid level of the molten iron.

[0075] The second processing module is used to predict the multiphase flow field of molten iron in the KR mechanical stirring process under different stirring speeds and immersion depths, based on the current geometric dimensions of the ladle and stirring paddle in the KR mechanical stirring process, as well as the initial liquid level of the molten iron.

[0076] The third processing module is used to obtain the critical rotational speed that affects the immersion depth of the stirring paddle based on the multiphase flow field of molten iron.

[0077] The fourth processing module is used to determine the relationship between the stirring paddle speed and immersion depth and the multiphase flow field of molten iron.

[0078] The fifth processing module is used to determine the relationship between the shape and size of the KR mechanical stirring vortex and the change of the multiphase flow field of molten iron based on the shape and size of the KR mechanical stirring vortex.

[0079] The sixth processing module is used to obtain the critical values ​​of the rotational speed and immersion depth at which the lowest point of the KR mechanical stirring vortex reaches the top of the stirring paddle, based on the relationship between the shape and size of the KR mechanical stirring vortex and the multiphase flow field of molten iron.

[0080] As one embodiment of the present invention, the relationship between the stirring paddle rotation speed and immersion depth and the multiphase flow field of molten iron is obtained as follows:

[0081]

[0082] Where C1 and C2 are constants; ε is the turbulent kinetic energy dissipation rate; h id n is the immersion depth; n is the rotational speed; n id The critical rotational speed that affects the effect of the impeller immersion depth on the multiphase flow field of molten iron.

[0083] As one embodiment of the present invention, the relationship between the shape and size of the KR mechanical stirring vortex and the multiphase flow field of molten iron is obtained as follows:

[0084] ΔH d =C3·ε 0.67

[0085] Where C3 is a constant; ΔH d ΔH represents the vortex depth. h ε is the vortex height; ε is the turbulent kinetic energy dissipation rate.

[0086] As one embodiment of the present invention, the relationship between the critical rotational speed and the critical immersion depth at which the lowest point of the KR mechanical stirring vortex reaches the top of the stirring paddle is expressed as follows:

[0087]

[0088] Where C4 is a constant; n cr The critical speed; h cr This represents the critical immersion depth.

[0089] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for matching the stirring speed and immersion depth of a KR mechanical stirrer, characterized in that, include: Step S1: Obtain the current geometric dimensions of the ladle and the agitator in the KR mechanical stirring process, as well as the initial liquid level of the molten iron; Step S2: Based on the current geometric dimensions of the ladle and the agitator in the KR mechanical stirring process, as well as the initial liquid level of the molten iron, predict the multiphase flow field of the molten iron in the KR mechanical stirring process under different agitator speeds and immersion depths. Step S3: Based on the multiphase flow field of molten iron, obtain the critical rotational speed that affects the immersion depth of the stirring paddle; Step S4: Determine the relationship between the stirring paddle speed and immersion depth and the multiphase flow field of molten iron; Step S5: Determine the relationship between the shape and size of the KR mechanical stirring vortex and the change of the multiphase flow field of molten iron based on the shape and size of the KR mechanical stirring vortex. Step S6: Based on the relationship between the shape and size of the KR mechanical stirring vortex and the change of the multiphase flow field of molten iron, obtain the critical values ​​of the rotational speed and immersion depth at which the lowest point of the KR mechanical stirring vortex reaches the top of the stirring paddle. The relationship between the stirring paddle speed and immersion depth and the multiphase flow field of molten iron is obtained as follows: Where C1 and C2 are constants; ε is the turbulent kinetic energy dissipation rate; h id n is the immersion depth; n is the rotational speed; n id The critical rotational speed that affects the effect of the impeller immersion depth on the multiphase flow field of molten iron; The relationship between the shape and size of the KR mechanical stirring vortex and the multiphase flow field of molten iron is obtained as follows: ΔH d =C3·ε 0.67 Where C3 is a constant; ΔH d ε represents the vortex depth; ε is the turbulent kinetic energy dissipation rate. The relationship between the critical rotational speed at which the lowest point of the KR mechanical stirring vortex reaches the top of the impeller and the critical immersion depth is: Where C4 is a constant; n cr The critical speed; h cr This represents the critical immersion depth.

2. A system for matching the KR mechanical stirring speed and immersion depth, characterized in that, include: The first processing module is used to obtain the geometric dimensions of the ladle and the agitator in the current KR mechanical stirring process, as well as the initial liquid level of the molten iron. The second processing module is used to predict the multiphase flow field of molten iron in the KR mechanical stirring process under different stirring speeds and immersion depths, based on the current geometric dimensions of the ladle and stirring paddle in the KR mechanical stirring process, as well as the initial liquid level of the molten iron. The third processing module is used to obtain the critical rotational speed that affects the immersion depth of the stirring paddle based on the multiphase flow field of molten iron. The fourth processing module is used to determine the relationship between the stirring paddle speed and immersion depth and the multiphase flow field of molten iron. The fifth processing module is used to determine the relationship between the shape and size of the KR mechanical stirring vortex and the change of the multiphase flow field of molten iron based on the shape and size of the KR mechanical stirring vortex. The sixth processing module is used to obtain the critical values ​​of the rotational speed and immersion depth at which the lowest point of the KR mechanical stirring vortex reaches the top of the stirring paddle, based on the relationship between the shape and size of the KR mechanical stirring vortex and the multiphase flow field of molten iron. The relationship between the stirring paddle speed and immersion depth and the multiphase flow field of molten iron is obtained as follows: Where C1 and C2 are constants; ε is the turbulent kinetic energy dissipation rate; h id n is the immersion depth; n is the rotational speed; n id The critical rotational speed that affects the effect of the impeller immersion depth on the multiphase flow field of molten iron; The relationship between the shape and size of the KR mechanical stirring vortex and the multiphase flow field of molten iron is obtained as follows: ΔH d =C3·ε 0.67 Where C3 is a constant; ΔH d ε represents the vortex depth; ε is the turbulent kinetic energy dissipation rate. The relationship between the critical rotational speed at which the lowest point of the KR mechanical stirring vortex reaches the top of the impeller and the critical immersion depth is: Where C4 is a constant; n cr The critical speed; h cr This represents the critical immersion depth.

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