Water model experiment method for simulating movement of electric furnace molten steel under electromagnetic effect

Abstract

The invention discloses a water model experiment method for simulating movement of electric furnace molten steel under an electromagnetic effect, and belongs to the field of electric furnace metallurgy in ferrous metallurgy, and the method specifically comprises the following steps: firstly, respectively calculating an electromagnetic stirring force generated by an electric furnace on a molten steel prototype and a stirring force generated by a magnetic stirrer in a water model; according to a similarity principle, calculating a similarity relationship between the electromagnetic stirring force of the prototype and the stirring force of the water model to ensure that the two are similar; then, according to the similarity relationship, determining parameters and models of the magnetic stirrers; according to the determined model of the magnetic stirrer, a magnetic stirring device comprising the magnetic stirrer and a stirrer is installed on the water model, including bottom installation or top installation; and finally, electrifying according to the parameters of the magnetic stirrer, enabling the magnetic stirrer to work, driving the stirrer to rotate at a constant speed to form rotational flow of the aqueous solution, and simulating the motion state of the electric furnace steel liquid under the electromagnetic effect. According to the invention, the movement behavior of the molten steel can be intuitively simulated by a hydraulic experiment.

Description

Technical Field

[0001] The invention belongs to the field of electric furnace metallurgy in iron and steel metallurgy, and in particular relates to a water model experimental method for simulating the movement of electric furnace molten steel under electromagnetic effect. Background Art

[0002] An electric furnace is a device that uses direct current or alternating current to generate an arc high temperature zone to melt and smelt metals. The electromagnetic field of direct current or alternating current acts on the conductive molten steel, generating a Lorentz force that causes the molten steel to rotate and form eddy currents. This effect is called electromagnetic stirring.

[0003] The magnetic field generated by the electrodes of the DC furnace acts on the molten steel, and the rotational force generated by the interaction between the eddy current and the magnetic field drives the molten steel to rotate; since the conduction direction of DC is fixed, the eddy current generated is stable and powerful; although the magnetic field generated by three-phase AC is alternating, the direction of the eddy current movement is also stable after the magnetic fields are superimposed on the molten steel. Therefore, for electric furnaces of the same power, the electromagnetic stirring effect of the molten steel in the DC furnace will be more powerful than that in the AC furnace.

[0004] Electromagnetic stirring can effectively improve the uniformity of molten steel, promote the mixing of slag and molten steel, accelerate heat and mass transfer, and thus improve the quality of molten steel.

[0005] In factories, some progress has been made in simulating electromagnetic stirring of arc furnaces using physical models by conducting practical research on the use of electrodes to energize or electromagnetic stirring devices installed around the furnace. Some studies have used low-melting-point metal alloys, such as tin, lead, bismuth, and mercury, to simulate the electromagnetic properties and flow behavior of molten steel. However, since metals are opaque and it is difficult to observe the movement of the liquid, and the cost is high, some metals such as lead and mercury have toxic side effects, making the experiment difficult.

[0006] By reducing the size between the model and the actual metallurgical reactor and utilizing the principle of similarity of dimensionless numbers such as Reynolds number and Euler number, the dynamic characteristics of aqueous solution fluid (such as flow rate, pressure, etc.) are simulated to predict the flow behavior of the metallurgical reactor under the same conditions. This is an important tool for predicting actual phenomena through laboratory models.

[0007] Using water or salt water as the simulation medium in the water model can simulate the flow behavior of molten steel very well, but the water model cannot simulate the electromagnetic stirring characteristics of molten steel. This is mainly due to the huge difference in the conductivity of water and molten steel. The conductivity of saturated salt water and low-carbon molten steel differs by 10 5 Above this order of magnitude, the rotation of water is almost unobservable using electromagnetic stirring. Therefore, there is currently no physical experiment using a water model to simulate the vortex effect formed by electromagnetic stirring.

[0008] If the flow behavior of electromagnetically stirred molten steel can be simulated through water model experiments, visualization effects can be achieved, and parameters such as fluid velocity and temperature can be obtained with low cost, safety and no side effects, the problem that water models cannot simulate the vortex formed by electromagnetically stirred molten steel will be solved.

[0009] The stirring method introduced in the traditional water model experiment is the air blowing method; as we all know, air blowing stirring and electromagnetic stirring are two methods with completely different principles and forms of action, so they are not suitable for simulating the movement of molten steel formed by electromagnetic stirring.

[0010] Another idea is to use a rotating paddle to form a vortex, which is similar in form to the vortex of electromagnetic stirring, and is simulated in a water model using a motor-driven rotating paddle. Different from the working principle of electromagnetic stirring, this method requires a shaft to drive the blades or paddle heads to rotate, which destroys the closed molten steel system. The electromagnetic field of the molten steel formed by the energization of the electrodes is a closed system and is not affected by the rotating shaft. Mechanical stirring is used to mix the liquid or slurry in the container through the rotational motion of the paddle. Electromagnetic stirring is to induce a rotating magnetic field at the bottom of the container, driving the liquid or slurry to rotate to achieve mixing. Mechanical rotation can generate high shear force, which is difficult to use in a closed system. Therefore, the rotating paddle mechanical stirring method is not suitable for simulating electromagnetic stirring to form vortices.

[0011] Based on the principle that like charges repel and opposite charges attract, the magnetic stirrer uses the magnetic field to drive the magnetic stirrer placed in the container to rotate in the liquid, achieving the purpose of stirring the closed liquid system. Generally, the stirrer is also equipped with a temperature control system, which can achieve temperature control and heating while stirring.

[0012] The difference between a magnetic stirrer and an electromagnetic stirrer is as follows: a magnetic stirrer drives the rotor through an external magnet, while an electromagnetic stirrer generates a rotating magnetic field to drive the liquid through electromagnetic induction; a magnetic stirrer drives the liquid to flow by rotating the rotor, while an electromagnetic stirrer causes the entire liquid to vortex. But more importantly, both use electromagnetic force to drive stirring, and the shear forces generated by both are similar, so both can be applied to closed systems, avoiding mechanical wear and contamination.

[0013] Therefore, from the perspective of principle and actual working conditions, it is completely feasible to use a magnetic stirrer to simulate electromagnetic stirring in the water model experiment of an electric arc furnace; and electromagnetic stirring can also provide feedback for parameter selection in the actual production process. Summary of the invention

[0014] In view of the above problems, the present invention proposes a water model method for simulating the movement of molten steel in an electric furnace under the electromagnetic effect, which overcomes the difficulty that the water model cannot simulate the vortex formed by molten steel under the action of electromagnetic stirring, and can intuitively simulate the movement behavior of molten steel using hydraulic experiments.

[0015] The water model method for simulating the movement of molten steel in an electric furnace under electromagnetic effect comprises the following specific steps:

[0016] Step 1: Calculate the electromagnetic stirring force generated by the electric furnace on the molten steel prototype;

[0017] F p = = I p B p L p sinα

[0018] In the formula, F p Represents the electromagnetic stirring force on the molten steel prototype; I p Represents current; B p Represents the magnetic field strength generated by the current; L p represents the distance from the current to the molten steel; α is the current direction and B p The angle between directions; the subscript p indicates the prototype.

[0019] Step 2: Calculate the stirring force generated by the magnetic stirrer in the water model;

[0020] F m =kB m I m Nd

[0021] Among them, F m represents the stirring force on the liquid in the water model; k represents the proportionality coefficient; B m Represents the magnetic field strength generated by the magnetic stirrer; I m represents the magnetization intensity of the magnetic stirrer; N represents the rotation speed of the magnetic stirrer; d represents the diameter of the magnetic stirrer; and the subscript m represents the water model.

[0022] Step 3: According to the similarity principle, select a similarity criterion that uses pressure difference to represent the flow relationship during fluid flow, and calculate the similarity relationship between the electromagnetic stirring force of the prototype and the stirring force of the water model to ensure that the two are similar;

[0023] The calculation formula of similarity coefficient is:

[0024] F p / S p *g / (ρ p *v p 2 )=F m / S m *g / (ρ m *v m 2 )

[0025] S p Indicates the area of ​​the prototype under pressure; S mrepresents the area of ​​the water model under pressure; g represents the acceleration due to gravity, ρ p represents the density of the steel prototype, ρ m represents the density of water prototype; v p represents the fluid velocity of the molten steel prototype, v m represents the fluid velocity of the water prototype;

[0026] Step 4: Determine the parameters and model of the magnetic stirrer based on the similarity relationship of the stirring force;

[0027] Parameters include the geometric dimensions, current, speed, shape and stirring direction of the stirrer, which are used to determine the model of the magnetic stirrer;

[0028] Step 5: According to the determined magnetic stirrer model, a magnetic stirring device including a magnetic stirrer and a stirring bar is installed on the water model;

[0029] The installation method includes bottom installation or top installation:

[0030] 1) Bottom installation: After the water model is filled with liquid, place the stirrer at the bottom of the water model and the magnetic stirrer at the bottom outside the water model. The stirrer is located directly above the center of the magnetic stirrer. Power is turned on to move the magnetic stirrer to drive the stirrer to rotate.

[0031] 2) Top installation: Place the stirrer on the top of the water model liquid, place a tray on the stirrer, and place the magnetic stirrer on the tray, just above the stirrer. Turn on the power to move the magnetic stirrer to drive the stirrer to rotate.

[0032] The number of magnetic stirring devices is not fixed. The current of the DC or AC furnace determines the number of stirrers, and a stirrer is placed at each current. When the magnetic stirring device is working, the rotation direction of the molten steel caused by the DC or AC furnace is determined by electromagnetic rules such as the left-hand rule, and the rotation direction of the stirrer is consistent with it.

[0033] Step 6. Power on the magnetic stirrer according to its parameters. The magnetic stirrer starts to work, driving the stirrer to rotate at a constant speed to form a vortex of the aqueous solution, simulating the movement of molten steel in an electric furnace under the electromagnetic effect.

[0034] The advantages of the present invention are:

[0035] 1. The present invention provides a water model method for simulating the movement of molten steel in an electric furnace under electromagnetic effect. The device used is simple and easy to obtain. In particular, the existing magnetic stirrers and stirrers are rich in variety and size. Different experimental requirements can be met by selecting different models of magnetic stirrers and stirrers of different shapes and sizes.

[0036] 2. The present invention provides a water model method for simulating the movement of molten steel in an electric furnace under the electromagnetic effect. Through the similarity principle, the stirring energy of the molten steel in the electric furnace under the electromagnetic effect is made similar to the stirring energy of the magnetic stirrer in the water model. The magnetic stirrer can obtain a wide range of stirring energy, thereby easily satisfying the similarity between the two.

[0037] 3. The water model method of the present invention for simulating the movement of molten steel in an electric furnace under electromagnetic effect is simple to operate. The stirring bar in the device used is small in size and can be placed at the bottom of the liquid surface or above the liquid surface, and the position can be flexibly adjusted.

[0038] 4. The water model method of the present invention for simulating the movement of molten steel in an electric furnace under electromagnetic effect overcomes the difficulty that the traditional electric furnace water model experiment cannot simulate the electromagnetic stirring flow, can intuitively simulate the movement behavior of molten steel, and can also be promoted in other metallurgical water model experiments under similar conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flow chart of a water model method for simulating the movement of molten steel in an electric furnace under electromagnetic effect.

[0040] Figure 2 This is an example diagram of the magnetic stirring device of the present invention being installed at the bottom of a water model.

[0041] Figure 3 It is a comparison diagram of the stirring vortex rotation of the molten steel and water models in the example of the present invention.

[0042] Among them, 1-top electrode, 2-arc, 3-electric furnace steel liquid, 4-electric furnace lining, 5-bottom anode, 6-magnetic stirrer, 7-tray, 8-stirring bar, 9-water model solution, 10-electric furnace water model lining; DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0044] The invention discloses a water model method for simulating the movement of molten steel in an electric furnace under electromagnetic effect. The method is suitable for simulating the movement behavior of molten steel in an electric furnace under electromagnetic stirring in a water model, or other experiments requiring simulation of stirring caused by electromagnetic action when immersed in metal liquid. The electromagnetic stirring movement of molten steel in a DC or AC electric arc furnace is simulated by installing a magnetic stirring device on the water model.

[0045] like Figure 1 As shown, the specific steps are as follows:

[0046] Step 1: Calculate the electromagnetic stirring force exerted by the electric furnace on the molten steel;

[0047] F p = = I p B p Lp sinα

[0048] In the formula, F p Represents the electromagnetic stirring force on the molten steel prototype, in Newton (N); I p Represents the current in ampere (A); B p Represents the magnetic field strength generated by the current, the unit is Tesla (T); L p represents the distance from the current to the molten steel, in meters (m); α is the angle between the current direction and the B direction, which is 90°; the subscript p represents the prototype.

[0049] Step 2: Calculate the stirring force generated by the magnetic stirrer in the water model;

[0050] F m =kB m I m Nd

[0051] Among them, F m represents the stirring force on the liquid in the water model, in Newton (N); k represents the proportionality coefficient, which is usually 1; B m Represents the magnetic field strength generated by the magnetic stirrer, in Tesla (T); I m represents the magnetization intensity of the magnetic stirrer, in ampere / meter (A / m); N represents the rotation speed of the magnetic stirrer, in revolutions per second (rps); d represents the diameter of the magnetic stirrer, in meter (m), and the subscript m represents the water model.

[0052] Step 3: According to the similarity principle, select a similarity criterion that uses pressure difference to represent the flow relationship during fluid flow, and calculate the similarity relationship between the electromagnetic stirring force of the prototype and the stirring force of the water model to ensure that the two are similar;

[0053] The similarity criterion adopts the Euler criterion, and the calculation formula is:

[0054] F p / S p *g / (ρ p *v p 2 )=F m / S m *g / (ρ m *v m 2 )

[0055] S p Indicates the area of ​​the prototype under pressure; S m represents the area of ​​the water model under pressure; g represents the acceleration due to gravity, ρ p Indicates the density of the molten steel prototype in kilograms per cubic meter (kg / m3 );ρ m represents the density of water prototype; v p Indicates the fluid velocity of the molten steel prototype in meters per second (m / s); v m represents the fluid velocity of the water prototype;

[0056] Step 4: Determine the parameters and model of the magnetic stirrer based on the similarity relationship of the stirring force;

[0057] Parameters include the geometric dimensions, current, speed, shape and stirring direction of the stirrer, which determine the model of the magnetic stirrer.

[0058] Step 5: According to the determined parameters of the magnetic stirrer, a magnetic stirring device including a magnetic stirrer and a stirring bar is installed on the water model;

[0059] The installation method includes bottom installation or top installation:

[0060] 1) Bottom installation: After the water model is filled with liquid, place the stirrer at the bottom of the water model and the magnetic stirrer at the bottom outside the water model. The stirrer is located directly above the center of the magnetic stirrer. Power is turned on to move the magnetic stirrer to drive the stirrer to rotate.

[0061] 2) Top installation: Place the stirrer on the top of the water model liquid, place a tray on the stirrer, and place the magnetic stirrer on the tray, just above the stirrer. Turn on the power to move the magnetic stirrer to drive the stirrer to rotate.

[0062] The number of magnetic stirring devices is not fixed. The current of the DC or AC furnace determines the number of stirrers, and a stirrer is placed at each current. When the magnetic stirring device is working, the rotation direction of the molten steel caused by the DC or AC furnace is determined by electromagnetic rules such as the left-hand rule, and the rotation direction of the stirrer is consistent with it.

[0063] Step 6. Power on the magnetic stirrer according to its parameters. The magnetic stirrer starts to work, driving the stirrer to rotate at a constant speed to form a vortex of the aqueous solution, simulating the movement of molten steel in an electric furnace under the electromagnetic effect.

[0064] Furthermore, according to experimental requirements, a video recording device can be placed outside the water model to record the flow state of the solution, and a mixing time recorder can be placed inside the water model to measure the mixing time of the solution. Other devices can also be used to measure the motion parameters of the fluid and observe similarities.

[0065] Embodiment 1:

[0066] The water model simulation stirring method for simulating the movement of molten steel in a DC electric furnace under electromagnetic effect is: Figure 2As shown, after the water model is filled with liquid, a stirring bar is placed in the bottom center of the water model, and a magnetic stirrer is placed in the bottom center outside the water model. The magnetic stirrer is powered on to move and drive the stirring bar to rotate.

[0067] Embodiment 2:

[0068] The water model simulation stirring method for simulating the movement of molten steel in a DC electric furnace under the electromagnetic effect is: a stirrer is placed at the top center of the water model liquid, a tray is placed on the stirrer, a magnetic stirrer is placed on the tray, located directly above the stirrer, and power is turned on to make the stirrer rotate.

[0069] Embodiment 3:

[0070] The water model simulation stirring method for simulating the movement of molten steel in a three-phase AC electric furnace under the electromagnetic effect is as follows: after the water model is filled with liquid, three stirring bars are placed at the bottom of the water model corresponding to the three electrodes of the electric furnace, and three magnetic stirrers are placed outside the water model directly below the three stirring bars. Power is turned on to make the three stirring bars rotate in the same direction.

[0071] Embodiment 4:

[0072] The water model simulation stirring method for simulating the movement of molten steel in a three-phase AC electric furnace under the electromagnetic effect is to place three stirring bars into the three electrode heads of the electric furnace corresponding to the top position of the water model liquid, place a tray on the stirring bars, and place three magnetic stirrers on the tray, which are located directly above the stirring bars. Power is turned on to make the stirring bars rotate in the same direction.

[0073] The calculation for Example 1 is:

[0074] A 150t DC electric arc furnace is a traditional open-top electric furnace with a nominal capacity of 150t. The steel tapping form is eccentric bottom type. The power supply consists of a transformer and a rectifier. It is equipped with a top electrode and a set of bottom anodes. The electrode diameter is 700mm. The geometric parameters of the prototype and water model are shown in Table 1.

[0075] Table 1

[0076]

[0077] The power supply parameters of the prototype and water model are shown in Table 2.

[0078] Table 2

[0079]

[0080] The electromagnetic stirring force generated by the electric furnace on the molten steel is difficult to calculate, which is affected by many factors such as the current and voltage, electromagnetic field distribution, molten steel properties, furnace structure, etc. According to calculations, the electromagnetic stirring force generated by the furnace on the molten steel is about 1×10 4 Newton.

[0081] According to the similarity principle, the similarity ratio of the stirring force is taken as 5000 using the similarity criterion. In the water model experiment, the magnetic flux is 0.1T, the magnetization intensity is 1A / m, the stirring speed is 500rpmin, and the length is 0.04m. It is estimated that the stirring force generated by the magnetic stirrer in the water model is about 2 Newtons.

[0082] The specific method of water model stirring method to simulate the movement of molten steel in a DC electric furnace under electromagnetic effect is:

[0083] After the 1 / 8 scale water model is filled with aqueous solution, a 0.04m long stirring bar is placed in the bottom center of the water model, and a magnetic stirrer is placed in the bottom center outside the water model. The stirring bar is powered on to rotate at a speed of 500 rpm. According to the experimental requirements, a video recording device can be placed outside the water model to record the flow state of the solution, and a mixing time recorder can be placed inside the water model to measure the mixing time of the solution. Other devices can also be used to measure the motion parameters of the fluid.

[0084] like Figure 3 As shown in the figure, after the DC furnace electrode is powered on, the rotation direction of the molten steel is counterclockwise. In the water model, after the magnetic stirrer is powered on, the stirring direction formed by the top or bottom stirrer is also counterclockwise.

Claims

1. A water model experimental method for simulating the movement of molten steel in an electric furnace under electromagnetic effect, characterized in that: The specific steps are as follows: Step 1: Calculate the electromagnetic stirring force F generated by the electric furnace on the molten steel prototype p And the stirring force F generated by the magnetic stirrer in the water model m ; Step 2: According to the similarity principle, select a similarity criterion that uses pressure difference to represent the flow relationship during fluid flow, and calculate the similarity relationship between the electromagnetic stirring force of the prototype and the stirring force of the water model to ensure that the two are similar; Step 3: Determine the parameters and model of the magnetic stirrer based on the similarity relationship of the stirring force; Step 4: According to the determined magnetic stirrer model, a magnetic stirring device including a magnetic stirrer and a stirring bar is installed on the water model; The installation method includes bottom installation or top installation: 1) Bottom installation: After the water model is filled with liquid, place the stirrer at the bottom of the water model, and place the magnetic stirrer at the bottom outside the water model. The stirrer is located directly above the center of the magnetic stirrer. Power is turned on to move the magnetic stirrer to drive the stirrer to rotate; 2) Top installation: place the stirrer on the top of the water model liquid, place a tray on the stirrer, and place the magnetic stirrer on the tray, just above the stirrer. Turn on the power to move the magnetic stirrer to drive the stirrer to rotate; Step 5. Power on the magnetic stirrer according to its parameters. The magnetic stirrer starts to work, driving the stirrer to rotate at a constant speed to form a vortex of the aqueous solution, simulating the movement of molten steel in an electric furnace under the electromagnetic effect.

2. A water model experimental method for simulating the movement of molten steel in an electric furnace under electromagnetic effect as claimed in claim 1, characterized in that: In the step 1, the electromagnetic stirring force generated by the molten steel prototype is calculated as follows: F p ==I p B p L p sinα In the formula, F p Represents the electromagnetic stirring force on the molten steel prototype; I p Represents current; B p Represents the strength of the magnetic field generated by the current; L p represents the distance from the current to the molten steel; α is the current direction and B p The angle between the directions; The subscript p indicates the prototype; The formula for calculating the stirring force generated by the magnetic stirrer in the water model is: F m =kB m I m Nd Among them, F m represents the stirring force on the liquid in the water model; k represents the proportionality coefficient; B m Represents the magnetic field strength generated by the magnetic stirrer; I m represents the magnetization intensity of the magnetic stirrer; N represents the rotation speed of the magnetic stirrer; d represents the diameter of the magnetic stirrer; subscript m represents the water model.

3. A water model experimental method for simulating the movement of molten steel in an electric furnace under electromagnetic effect as claimed in claim 1, characterized in that: In the step 2, the calculation formula of the similarity coefficient is: F p / S p *g / (ρ p *v p 2 )=F m / S m *g / (ρ m *v m 2 ) S p Indicates the area of ​​the prototype under pressure; S m represents the area of ​​the water model under pressure; g represents the acceleration due to gravity, ρ p represents the density of the steel prototype, ρ m represents the density of water prototype; v p represents the fluid velocity of the steel prototype, v m Represents the fluid velocity of the water prototype.

4. A water model experimental method for simulating the movement of molten steel in an electric furnace under electromagnetic effect as claimed in claim 1, characterized in that: In the step three, the parameters include the geometric size, current, rotation speed, shape and stirring direction of the stirrer; and the parameters are further used to determine the model of the magnetic stirrer.

5. A water model experimental method for simulating the movement of molten steel in an electric furnace under electromagnetic effect as claimed in claim 1, characterized in that: In the step 4, the number of magnetic stirring devices is not fixed, and the number of currents flowing through the DC or AC furnace determines the number of stirrers, and a stirrer is placed at each current flow. When the magnetic stirring device is working, the rotation direction of the molten steel caused by the DC or AC furnace is determined by the electromagnetic rule of the left-hand rule, and the rotation direction of the stirrer is consistent with it.

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