JPS6058399B2 - Stirring device for reverberatory furnace - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a device for stirring molten metal in a reverberatory furnace. 2. Description of the Related Art A stirring device that uses a moving magnetic field as a means for stirring molten metal in a reverberatory furnace is known. Figures 1 to 3 show an example of a stirring device that uses a moving magnetic field to stir the molten metal inside a reverberatory furnace for aluminum and its alloys. The molten metal is guided to the outside of the reverberatory furnace 1 through the channel trough 2, and the molten metal in the external channel trough 2 is guided to the outside of the reverberatory furnace 1. The molten metal in the reverberatory furnace 1 is stirred by being made to flow by the pump 3. To explain the electromagnetic pump 3 in detail, the electromagnetic pump 3 is made of a refractory material and is formed into a tubular shape with a rectangular cross section, and both ends are connected to the external flow path gutter 2 to serve as a flow path for the molten metal. Pipe 4 and a pair of pump refractory tubes 4 that are disposed facing each other on the outside of the pump refractory tube 4 along opposing tube walls and that generate a moving magnetic field to apply thrust to the molten metal within the pump refractory tube 4. It is equipped with an inductor 5. In this example, as the inductor 5, a three-phase induction coil 5c is wound around an iron core 5b housed in a frame 5a (in FIG. 4, the part of the induction coil that is directly wound around the iron core 5b) is not shown, and the illustrated induction coil 5c is a protruding portion due to winding of the induction coil around the iron core 5b).
d, and when a three-phase alternating current is passed through the induction coil 5c, it generates a moving magnetic field that advances along the flow path of the refractory tube 4, causing the molten metal in the pump refractory tube 4 to flow. It shows. 7 The sinusoidal alternating magnetic flux generated from such an inductor 5 and giving thrust to the molten metal in the pump refractory tube 4 is canceled by the magnetic flux generated by eddy currents generated in the molten metal while passing through the molten metal (electrical conductor). Therefore, it is attenuated towards the inside of the molten metal. Here, the specific resistance of the molten metal is ρ [μΩ・d], the relative magnetic permeability is also μ, the frequency of the magnetic flux penetrating the molten metal is FCHz], and the magnetic flux generated from the inductor 5 penetrates into the molten metal and becomes the molten metal. The penetration depth that can provide thrust is δ

If it is [0],
δ is δ=5.04/I! f...
...It is expressed as (1). Strictly speaking, f is the relative speed difference between the molten metal (aluminum) flowing inside the refractory tube 4 and the advancing speed of the advancing magnetic field generated by the inductor 5, but if the molten aluminum flows inside the refractory tube 4, In the device in question, the flow velocity of
Generally, the power supply frequency applied to the inductor may be used because it is significantly slower than the traveling speed of the magnetic flux. By the way, conventionally, the electromagnetic pump 3 used in the above-mentioned device includes:
It has been common knowledge among those skilled in the art to circulate the molten metal in the refractory pipe 4, that is, the external channel trough 2, at high speed by using a high-pressure, low-flow type pipe with a total lift of several tens of cubic tons. When using the electromagnetic pump 3 with high pressure and low flow rate specifications, the inner dimension D of the refractory tube 4 in the direction facing the inductor should be D≦2δ, preferably D equal to or less than δ. It was taken for granted that it should be selected as a value. This is because in conventional electromagnetic pumps with high pressure and low flow specifications that generate relatively high pressure, if D = 3δ, for example, the high pressure generated near the inner peripheral surface of the pump refractory tube 4 causes the molten metal to A flow of molten metal flows from the inner circumferential surface of the pump refractory tube 4 toward the center of the refractory tube 4, where there is almost no thrust, and the flow within the refractory tube 4 is turbulent. The pressure of the reverberant furnace 1 decreases, resulting in the inability to obtain the necessary flow rate and the inability to stir the molten metal in the reverberatory furnace 1 sufficiently. This is because that. However, if D≦δ, stirring can be performed sufficiently, but on the other hand, other problems arise. This is because, to explain this using a reverberatory furnace for aluminum with a capacity of 20 tons as a specific example, in a reverberatory furnace with such a capacity, it is necessary to make the temperature distribution of the molten metal in the reverberatory furnace uniform and to reduce the temperature inside the molten aluminum. The appropriate flow rate Q required for stirring to satisfy the purpose of uniformly mixing the added alloy is 1000.
e/Min. The flow velocity v of the pump refractory pipe is 100cm/Sec. It is known that the following is preferable, and the flow passage cross-sectional area of the pump refractory pipe 4 is S
CC7lf], then s=t167d...(2)
becomes. On the other hand, when the molten metal is aluminum, in equation (1) above, ρ=20 μΩ·Cflt, μ=1, and assuming that a commercial frequency is used, f=60 Hz is substituted. And D=δ=2.9c! If n is selected, from S=167cF1f in equation (2), the width direction of the pump fireproof tube 4 (
The inner dimension C in the horizontal direction (in Fig. 4) is c=? =ywa≠57
．． By the way, the cross-sectional shape of D2-q pump fireproof pipe 4 is 2.9C7? ! ×57.
5d, which makes it difficult to remove oxides in the molten metal adhering to the inside of the pump refractory tube 4 by mechanical means. Furthermore, it becomes necessary to manufacture an inductor 5 with a large dimension in the width direction (horizontal direction in Fig. 3) to match the width of the pump fireproof tube 4, which causes problems such as an increase in the manufacturing cost of the inductor 5. . To solve this problem, the conventional method is to lower the power frequency supplied to the inductor 5 to reduce the dimension of δ, that is, D
The solution for those skilled in the art was to increase the size of C and thereby reduce the size of C accordingly. However, when the frequency is lowered from the commercial frequency (50 Hz, 60 Hz), it becomes necessary to provide a frequency conversion device to supply current to the inductor, which causes new problems such as extra cost. The present invention has been made in consideration of the above circumstances, and includes an electromagnetic pump with low pressure and large flow specifications, a commercial frequency current supplied to the inductor, and a D dimension of the fireproof tube that is twice as large as δ. By setting it to 5 times,
This makes it easier to mechanically remove deposits such as oxides in the molten metal that adhere to the inner surface of refractory pipes, eliminates the need for a frequency converter, etc., and makes the temperature distribution in the molten metal uniform. Another object of the present invention is to provide a stirring device for a reverberatory furnace that can fully satisfy the purpose of stirring the molten aluminum, such as uniformly mixing additive alloys in the molten aluminum. Hereinafter, this invention will be explained based on an embodiment shown in FIGS. 4 to 8. In these figures, parts having the same functions as those shown in FIGS. 1 to 3 will be explained as follows. 1 to 3 to simplify the explanation. The apparatus of the present invention is formed of a refractory material into a tubular shape with a rectangular cross section, and a reverberatory furnace 1". A pump refractory tube 4'' disposed outside of the pump refractory tube 4'' and a pump refractory tube 4'' disposed opposite to each other along the opposing pipe wall of the pump refractory tube 4'' with the pump refractory tube 4'' in between and in the flow path of the pump refractory tube 4''. An electromagnetic pump 3'' consists of a pair of inductors 5'' that generate a moving magnetic field to flow the molten metal 6 guided into the pump refractory tube 4'', and both ends of the pump refractory tube 4'' are connected to each other. The reverberatory furnace "
The device is similar to the conventional ones in that it is equipped with an external flow path gutter 2'' that guides the molten metal 6 melted by the heating burner 7 inside the pump refractory tube 4'', but these other,
It has the following new configuration. In order to be able to pump the molten metal 6 inside the reverberatory furnace 1'' under low pressure, a circulation path for the molten metal 6 is formed horizontally by an external channel gutter 2'', and the molten metal is circulated through the circulation path by the electromagnetic pump 3''. The head (1
．． For aluminum reflection paths with a capacity of 5 tons to 50 tons, a low-pressure, large-flow type with a pressure of approximately 4aTt to 10cm is used, and an electromagnetic pump 3 is used.
In the pump refractory tube 4'', the inner dimension D in the direction in which the inductor 5'' faces is 2 to 5 times the penetration depth δ of the magnetic field due to the inductor 5'' (in one embodiment, 2. 9 times). With such a configuration, when the pressure applied to the molten metal in the pump refractory tube 4'' is reduced by the sinusoidal alternating magnetic flux generated from the inductor 5'' of the electromagnetic pump 3'', the pump refractory tube 4''
When the inner dimension D in the direction in which the inductor 5'' of the pump refractory pipe 4'' faces is made 2 to 5 times the penetration depth δ of the sinusoidal alternating magnetic flux, the molten metal in the direction in which the inductor 5'' in the pump refractory tube 4'' faces As shown in Figure 8, although the thrust distribution of the pump refractory tube 4'' is large on the inner surface side and small on the center side, it is a parabolic shape due to the effect of turbulent flow of the molten metal inside the pump refractory tube 4''. Therefore, the range (
The generation of molten metal flow from zone A) to zone B, where no thrust is generated, is so small that it does not pose a practical problem, and the flow rate does not decrease, so reverberatory furnace 1
This is based on the experimental discovery that it can fully satisfy the purpose of stirring molten metal.Hereinafter, the apparatus constructed in this way will be constructed using an aluminum tube with a capacity of 20 tons as described above. A specific example will be explained using a reverberatory furnace in which the flow passage cross-sectional area S of the pump refractory tube is 167 cT1. In the above equation (1), if f is a commercial frequency of 60 Hz, δ = 2.9. (Cm), the inner dimension of the pump refractory tube 4'' D = 2.9 δ = 8.4 cm1 Therefore, c = A''.19.9 cm, and the cross-sectional shape of the flow path of the refractory tube 4'' is 8. 4cm x 19.9c
m, and although a commercial frequency of 60 Hz was used, the work of removing deposits such as molten metal oxides adhering to the inside of the pump refractory pipe 4'' by mechanical means was different from that of the conventional flat pipe (2 .9 crn x 57.5 cm). In the above-mentioned embodiment, D = 2.9 δ", but as stated earlier, if 2 δ≦D≦5 δ, ,
No matter what value is selected, the purpose of stirring can be fully satisfied. As explained above, the device of the present invention includes a pump refractory tube through which molten metal in a reverberatory furnace is guided, and a pair of inductors arranged facing each other outside of the pump tube and applying thrust to the molten metal by a moving magnetic field. In this electromagnetic pump, the internal dimension D of the pump refractory tube in the direction facing the inductor is selected to be 2 to 5 times the penetration depth δ of the magnetic field generated from the inductor. j By using an inductor that lowers the pressure generated in the molten metal by the generated magnetic field, the molten metal in the pump refractory tube flows smoothly, and the purpose of stirring can be fully satisfied. , even when supplying commercial frequency power to the inductor, the dimension D of the pump refractory tube in the direction facing the inductor is Since the cross-sectional shape of the flow path can be improved by making the dimension C larger and smaller in the width direction, it is possible to obtain the effect that it becomes easier to remove deposits deposited inside the pump refractory pipe by mechanical means. Furthermore, it is sufficient to use a narrow inductor to match the width dimension of the pump refractory pipe, making it easier to manufacture the inductor. The manufacturing cost can be reduced.

[Brief explanation of the drawing]

Figures 1 to 3 show a conventional stirring device. Figure 1 is a schematic plan view, Figure 2 is a sectional view taken along the line ■-■ in Figure 1, and Figure 3 is a cross-sectional view of Figure 2. ■A sectional view taken along the line 1-■, and FIGS. 4 to 8 show an embodiment of the present invention. FIG. 4 is a schematic plan view, and FIG. Figure 6 is a cross-sectional view taken along line ■-■ in Figure 4, Figure 7 is a cross-sectional view taken along line ■--■ in Figure 5, and Figure 8 is a cross-sectional view taken along line ■-■ in Figure 5. There is a graph showing the thrust force distribution between the side tube walls. 1″・・・Reverberatory furnace, 2″・・・External channel gutter,
3″・・・Electromagnetic pump, 4″・・・Pump fireproof pipe,
5''...Inductor, 5a''...Frame, 5b
″・・・Iron core, 5C″・・・Induction coil,
5d″・・・Refractory.

Claims (1)

[Scope of Claims] 1. A pump refractory pipe 4' formed of a refractory material into a tubular shape with a rectangular cross section and arranged outside the reverberatory furnace 1'.
The molten metal guided into the pump refractory tube is caused to flow by generating a magnetic field that moves along the opposing walls of the pump refractory tube and facing each other with the pump refractory tube in between, and along the flow path of the pump refractory tube. an electromagnetic pump 3' consisting of a pair of inductors 5' that
In the stirring device for a reverberatory furnace, the stirring device for a reverberatory furnace is provided with an external flow path gutter 2' that communicates with the inside of the reverberatory furnace from both horizontal ends of the refractory furnace and guides the molten metal in the reverberatory furnace into the pump refractory tube. The dimensions are the specific resistance of the molten metal ρ [μΩ・cm],
Similarly, δ=5.04√(ρ
A stirring device for a reverberatory furnace, characterized in that the stirring device is selected to have a penetration depth of 2 to 5 times the penetration depth δ expressed by /μ·f).