Electric furnace

Abstract

To provide an electric furnace which is excellent in heating efficiency and further has a long service life.SOLUTION: The on-off conditions of a first on-off valve 21 and a fourth on-off valve 24 and the on-off conditions of a second on-off valve 22 and a third on-off valve 23 are alternately switched in reverse conditions at regular intervals to alternately circulate a gas through a first circulation passage p1 of feeding the same from a blower fan 20 to a first accumulator 13 through a first passage 15 and returning the same from a second accumulator 14 to the blower fan 20 through a second passage 16 and a second circulation passage p2 of feeding the same from the blower fan 20 to the second accumulator 14 through the first passage 15 and returning the same from the first accumulator 13 to the blower fan 20 through the second passage 16, and the heated gas is alternately fed to a material T to be heated from a longitudinal direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric furnace used for heat treating metals and non-ferrous metals. [Background technology]

[0002] 2. Description of the Related Art Electric furnaces that use electricity as a heat source exist as furnaces for heat treating metals and non-ferrous metals (see, for example, Patent Document 1). The electric furnace shown in Patent Document 1 is provided with a cooling fan on the outside of the furnace body, and this cooling fan has a cooling function of supplying outside air to the inside of the furnace body and dissipating the heated air inside the furnace body to the outside.

[0003] As such a conventional electric furnace, for example, the one shown in Figures 4 and 5 is known. The electric furnace shown in Figure 4 has metal heaters 31 provided on the left and right sides inside the furnace body 30, and a rotary fan 32 provided in the upper center of the furnace body 30. The air inside the furnace body 30 is heated by these metal heaters 31, and the heated air is circulated by the rotary fan 32 to heat the material T to be heated.

[0004] 5 has an air heater 41 attached to the outside of the furnace body 40, and external air is heated through the air heater 41 and taken into the furnace body 40, and the heated air heats the material to be heated T. The heated air is discharged to the outside of the furnace body 40. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-137781 A Summary of the Invention [Problem to be solved by the invention]

[0006] The electric furnaces of the prior art shown in Patent Document 1 and in Figs. 4 and 5 all use electricity as a heating source, and are therefore highly desirable from the standpoint of carbon neutrality.

[0007] However, there is a demand for further improvement in the heating efficiency of all of these electric furnaces. That is, the electric furnace shown in Patent Document 1 has a cooling function using a cooling fan, which naturally reduces the heating efficiency.

[0008] In addition, the electric furnace shown in Fig. 4 heats the air inside the furnace body 30 with metal heaters 31 installed on the left and right sides inside the furnace body 30, and circulates it with a rotary fan 32, so the agitation effect of the heated air is insufficient, and there are problems with heating efficiency. In addition, the heated air always acts on the material T from a fixed direction, which causes problems with heating efficiency. These problems are particularly noticeable when the shape of the material T is complex.

[0009] In addition, since the rotary fan 32 in this electric furnace is installed inside the furnace body 30, which is at high temperature, it is prone to damage such as deformation and vibration due to loss of impeller balance, and there are also problems in that it has a short lifespan.

[0010] 5, the air outside the furnace body 40 (i.e., air at room temperature) is heated by the air heater 41, and the heated air is discharged after acting on the material to be heated T. Therefore, it is necessary to constantly heat the air at room temperature to the required high temperature. Therefore, energy loss is large and heating efficiency is low.

[0011] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an electric furnace which is excellent in heating efficiency and has a long fan life. [Means for solving the problem]

[0012] In order to achieve the above object, the electric furnace (1) of the present invention comprises: A furnace that uses electricity as a heat source and circulates gas inside a furnace body (10) to heat a material to be heated (T), a first heater (11) provided on one side in a left-right direction inside the furnace body (10) and configured to heat the gas; a second heater (12) provided on the other side of the interior of the furnace body (10) in the left-right direction and configured to heat the gas; a first heat accumulator (13) provided on one side in the left-right direction outside the furnace body (10) and communicating with the first heater (11); a second heat accumulator (14) provided on the other side in the left-right direction outside the furnace body (10) and communicating with the second heater (12); a first passage (15) and a second passage (16) separately communicating the first heat accumulator (13) and the second heat accumulator (14), respectively, outside the furnace body (10); The air is connected to both the first passage (15) and the second passage (16) and is drawn in from the second passage (16) side. gas a blower fan (20) capable of blowing air to the first passage (15); a first on-off valve (21) provided in the first passage (15) between a connection position (X) of the blower fan (20) and the first heat accumulator (13); a second on-off valve (22) provided in the first passage (15) between a connection position (X) of the blower fan (20) and the second heat accumulator (14); a third on-off valve (23) provided in the second passage (16) between a connection position (Y) of the blower fan (20) and the first heat accumulator (13); a fourth on-off valve (24) provided in the second passage (16) between a connection position (Y) of the blower fan (20) and the second heat accumulator (14), The open / close states of the first on-off valve (21) and the fourth on-off valve (24) and the open / close states of the second on-off valve (22) and the third on-off valve (23) are alternately switched between opposite states at regular intervals, so that the gas is alternately circulated through a first circulation path (P1) in which the gas is sent from the blower fan (20) through the first passage (15) to the first heat accumulator (13), and then from the second heat accumulator (14) through the second passage (16) to the blower fan (20), and a second circulation path (P2) in which the gas is sent from the blower fan (20) through the first passage (15) to the second heat accumulator (14), and then from the first heat accumulator (13) through the second passage (16) to the blower fan (20), and the heated gas is alternately sent from the left and right directions to the material to be heated (T).

[0013] The present invention also provides an electric furnace 1 that uses electricity as a heat source and circulates gas inside a furnace body (10) to heat a material to be heated (T), a first heater (11) provided on one side in a left-right direction inside the furnace body (10) and configured to heat the gas; a second heater (12) provided on the other side of the interior of the furnace body (10) in the left-right direction and configured to heat the gas; a first heat accumulator (13) provided on one side in the left-right direction outside the furnace body (10) and communicating with the first heater (11); a second heat accumulator (14) provided on the other side in the left-right direction outside the furnace body (10) and communicating with the second heater (12); a first passage (15) and a second passage (16) separately communicating the first heat accumulator (13) and the second heat accumulator (14), respectively, outside the furnace body (10); a first fan (25) provided in the first passage (15) for blowing the gas in one direction; a second fan (26) provided in the second passage (16) and configured to blow the gas in the other direction, The first fan (25) and the second fan (26) are alternately rotated for a fixed period of time to alternately circulate the gas through a first circulation path (P1) passing through the first passage (15) and a second circulation path (P2) passing through the second passage (16), thereby sending the heated gas alternately from the left and right directions to the material to be heated (T).

[0014] In the present invention, the gas is air.

[0015] Furthermore, the present invention is characterized in that the gas is an atmospheric gas other than air.

[0016] Here, the symbols in parentheses indicate corresponding elements or items in the drawings and in the detailed description to be described later. Effect of the Invention

[0017] In the electric furnace of the present invention, the open / close states of the first and fourth on-off valves and the open / close states of the second and third on-off valves are alternately switched between opposite states at regular intervals, so that heated gas is alternately sent from the left and right directions to the material to be heated, thereby achieving high heating efficiency. That is, by alternately sending the heated gas from the left and right directions, the gas inside the furnace body can be effectively agitated. Therefore, the entire material to be heated can be heated evenly in a short time. Also, by alternately sending the heated gas from the left and right directions, the material to be heated can be heated more effectively than when it is always sent from a fixed direction.

[0018] Also heated gas Since the heat is circulated without being released outside the electric furnace, gas Compared to using a conventional heater, it has less energy loss and is more efficient at heating. In addition, since the first passage and the second passage are connected to the first heat storage device and the second heat storage device, the heating efficiency can be further improved by utilizing the heat stored in these first heat storage device and the second heat storage device. Furthermore, since the blower fan is provided outside the furnace body, breakdowns due to the influence of heat can be reduced and the life of the furnace can be extended, compared to when the blower fan is provided inside the furnace body.

[0019] According to the present invention, the first fan and the second fan are alternately rotated for a certain period of time to alternately circulate the gas in a first circulation direction passing through the first passage and in a second circulation direction passing through the second passage, and the heated gas is alternately sent from the left and right directions to the material to be heated, thereby achieving high heating efficiency. gas High heating efficiency can also be achieved by circulating the heat without dissipating it and by utilizing the heat of the first and second heat accumulators. In addition, since the first and second fans are installed outside the furnace body, the effects of heat can be avoided and their lifespan can be extended.

[0020] Furthermore, according to the present invention, since air is used as the gas, the cost of materials used for heating can be reduced, which contributes to improving the heating efficiency.

[0021] Furthermore, since the present invention utilizes an atmospheric gas other than air as the gas, the heating efficiency can be improved by selecting a gas suitable for the content of the heat treatment.

[0022] In this way, the open / close states of the first and fourth valves and the open / close states of the second and third valves are alternately switched between opposite states at regular intervals to send heated gas alternately from the left and right directions to the material to be heated, thereby achieving high heating efficiency, but this configuration is not described at all in the above-mentioned patent documents. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a front view showing an electric furnace according to a first embodiment of the present invention, illustrating a state in which gas is fed from right to left inside the furnace. [Diagram 2] FIG. 1 is a front view showing an electric furnace according to a first embodiment of the present invention, illustrating a state in which gas is fed from left to right inside the furnace. [Diagram 3] FIG. 4 is a front view showing an electric furnace according to a second embodiment of the present invention. [Figure 4] FIG. 1 is a front view showing the configuration of an electric furnace according to a conventional example. [Diagram 5] FIG. 13 is a front view showing an electric furnace according to another conventional example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An electric furnace 1 according to a first embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 shows the electric furnace 1 in a state in which gas is fed from right to left inside the furnace body 10, and Figure 2 shows the electric furnace 1 on the opposite side to Figure 1, that is, in a state in which gas is fed from left to right inside the furnace body 10.

[0025] The electric furnace 1 according to this embodiment uses electricity as a heat source, circulates gas inside the furnace body 10, and heats the material T placed inside the furnace body 10. The material T may be placed in a fixed state, or may be placed in a movable (rotatable, etc.) state.

[0026] This electric furnace 1 is equipped with a first heater 11, a second heater 12, a first heat accumulator 13, a second heat accumulator 14, a first passage 15, a second passage 16, a blower fan 20, a first on-off valve 21, a second on-off valve 22, a third on-off valve 23 and a fourth on-off valve 24.

[0027] The first heater 11 is provided on the right side inside the furnace body 10, and heats the gas circulating inside the furnace body 10 by electricity. The second heater 12 is provided on the left side inside the furnace body 10 and also heats the gas by electricity. The first heater 11 and the second heater 12 are preferably made of silicon carbide (SiC) or the like, which has excellent heat resistance.

[0028] The first heat accumulator 13 is provided on the right side outside the furnace body 10 and communicates with the first heater 11 . The second heat accumulator 14 is provided on the left side outside the furnace body 10 and communicates with the second heater 12 . Each of the first heat accumulator 13 and the second heat accumulator 14 is provided with a heat storage material therein.

[0029] The first passage 15 is disposed outside the furnace body 10 and is provided in a state in which the first heat accumulator 13 and the second heat accumulator 14 communicate with each other. The second passage 16 is also disposed outside the furnace body 10 and is provided in a state in which the first heat accumulator 13 and the second heat accumulator 14 communicate with each other.

[0030] One blower fan 20 is provided and is connected to both the first passage 15 and the second passage 16 in a state where it is interposed approximately in the middle of each of them, and by operating a first on-off valve 21, a second on-off valve 22, a third on-off valve 23 and a fourth on-off valve 24, gas is blown to either the first heat accumulator 13 on the right side via the first passage 15 or the second heat accumulator 14 on the left side via the first passage 15. The connection position of the blower fan 20 to the first passage 15 is indicated by symbol X, and the connection position of the blower fan 20 to the second passage 16 is indicated by symbol Y.

[0031] The blower fan 20 has a discharge port 20a and a suction port 20b, sends gas from the discharge port 20a to the first passage 15, and receives gas from the second passage 16 through the suction port 20b. A first connecting pipe K1 is provided between the discharge port 20a and the first passage 15, and a second connecting pipe K2 is provided between the suction port 20b and the second passage 16.

[0032] The first on-off valve 21 is provided between a connection position X of the blower fan 20 to the first passage 15 and the first heat accumulator 13, and the second on-off valve 22 is provided between a connection position X of the blower fan 20 to the same first passage 15 and the second heat accumulator 14. The third on-off valve 23 is provided between a connection position Y of the blower fan 20 to the second passage 16 and the first heat accumulator 13, and the fourth on-off valve 24 is provided between a connection position Y of the blower fan 20 to the same second passage 16 and the second heat accumulator 14.

[0033] This electric furnace 1 can be operated as follows. That is, this electric furnace 1 circulates the gas by alternately switching between a first circulation path P1, which sends the gas from the blower fan 20 through the first passage 15 to the first heat accumulator 13, and then passes from the second heat accumulator 14 through the second passage 16 to the blower fan 20, and a second circulation path P2, which sends the gas from the blower fan 20 through the first passage 15 to the second heat accumulator 14, and then passes from the first heat accumulator 13 through the second passage 16 to the blower fan 20, at regular intervals (for example, every 30 seconds or every minute).

[0034] When gas is sent to the first circulation path P1 (from right to left inside the furnace body 10) (see Figure 1), the first on-off valve 21 of the first passage 15 and the fourth on-off valve 24 of the second passage 16 are opened, and the second on-off valve 22 of the first passage 15 and the third on-off valve 23 of the second passage 16 are closed. Conversely, when gas is sent to the second circulation path P2 (from left to right inside the furnace body 10) (see Figure 2), the first on-off valve 21 of the first passage 15 and the fourth on-off valve 24 of the second passage 16 are closed, and the second on-off valve 22 of the first passage 15 and the third on-off valve 23 of the second passage 16 are opened. In either case, one blower fan 20 is rotated in the same direction. The opening and closing of these on-off valves 21 to 24 can be automatically performed by a control device.

[0035] When gas is sent to the first circulation path P1, the gas sent by the blower fan 20 passes through the first passage 15 and the first on-off valve 21 to reach the first heat accumulator 13, where it is heated by the heat stored in the first heat accumulator 13 and is further heated by the first heater 11. The gas heated by the first heater 11 applies heat treatment to the material T to be heated inside the furnace body 10. At this time, the material T to be heated is strongly subjected to heat from the right direction.

[0036] The gas that has been subjected to the heat treatment of the material to be heated T is heated again by the second heater 12, reaches the second heat accumulator 14, and after exchanging heat with the second heat accumulator 14 (after storing heat in the second heat accumulator 14), passes through the second passage 16 and the fourth on-off valve 24, and returns to the blower fan 20. This circulation continues for a certain period of time (for example, 30 seconds or 1 minute).

[0037] Then, when the gas is sent to the second circulation path P2 after a certain time has elapsed, the gas sent by the blower fan 20 passes through the second passage 15 and the second on-off valve 22 to reach the second heat accumulator 14, where it is heated by the heat stored in the second heat accumulator 14 and is further heated by the second heater 12. The gas heated by the second heater 12 applies heat treatment to the material T to be heated inside the furnace body 10. At this time, the material T to be heated is strongly subjected to heat from the left direction.

[0038] The gas that has been subjected to the heat treatment on the material to be heated T is heated again by the first heater 11, reaches the first heat accumulator 13, and exchanges heat with the first heat accumulator 13, passes through the second passage 16, passes through the third on-off valve 23, and returns to the blower fan 20. This circulation continues for a certain period of time (for example, 30 seconds or 1 minute).

[0039] According to the electric furnace 1 configured in this manner, strong heat can be applied alternately to the material T from the right and left directions, and the gas flow is alternately switched between the first circulation path P1 (second circulation path P2) and the second circulation path P2 (first circulation path P1), so that the gas inside the furnace body 10 can be effectively agitated. Therefore, the material T can be heated more uniformly throughout.

[0040] Furthermore, since the electric furnace 1 circulates the heated gas without dissipating it outside the electric furnace 1, the gas can be heated efficiently with little electric energy. Furthermore, since the first heat accumulator 13 and the second heat accumulator 14 are provided, the heat stored therein can be utilized to heat the gas even more efficiently. Furthermore, since the blower fan 20 is provided outside the furnace body 10, the influence of heat inside the furnace body 10 can be avoided, and the life of the furnace body 10 can be extended.

[0041] Next, an electric furnace 1 according to a second embodiment of the present invention will be described with reference to Fig. 3. Fig. 3 is a partial front view of the electric furnace 1 according to this embodiment.

[0042] This electric furnace 1 also uses electricity as a heat source and is configured to circulate gas inside the furnace body 10 to heat the material to be heated T, and is equipped with a first heater 11, a second heater 12, a first heat accumulator 13, a second heat accumulator 14, a first passage 15, a second passage 16, a first fan 25 and a second fan 26.

[0043] The first heater 11 is provided on the right side inside the furnace body 10 and heats the gas by electricity. The second heater 12 is provided on the left side inside the furnace body 10 and also heats the gas by electricity.

[0044] The first heat accumulator 13 is provided on the right side outside the furnace body 10 and communicates with the first heater 11. The second heat accumulator 14 is provided on the left side outside the furnace body 10 and communicates with the second heater 12. The first heat accumulator 13 and the second heat accumulator 14 each contain a heat storage material capable of storing heat.

[0045] The first passage 15 is provided outside the furnace body 10 and connects the first heat accumulator 13 and the second heat accumulator 14. The second passage 16 is also provided outside the furnace body 10 and connects the second heat accumulator 14 and the first heat accumulator 13.

[0046] The first fan 25 is provided at approximately the middle of the first passage 15 and blows gas from right to left inside the furnace body 10. The second fan 26 is provided at approximately the middle of the second passage 16 and blows gas from left to right inside the furnace body 10. The first fan 25 and the second fan 26 each rotate in one direction.

[0047] The electric furnace 1 can be operated by alternately rotating the first fan 25 and the second fan 26 for a certain period of time. That is, by rotating the first fan 25, the gas is circulated through the first circulation path P1 passing through the first passage 15 for a certain period of time (for example, about 30 seconds to 1 minute). As a result, the gas is heated in the first heat accumulator 13, and then heated in the first heater 11, and the heated gas heats the material T to be heated. Here, strong heat can be applied to the right side of the material T to be heated. The gas that has heated the material T to be heated is heated when passing through the second heater 12, and then exchanges heat in the second heat accumulator 14, and is returned to the first fan 25 through the first passage 15.

[0048] After circulating the gas through the first circulation path P1 for a certain period of time, the second fan 26 is rotated while the rotation of the first fan 25 is stopped. This causes the gas to circulate through the second circulation path P2 passing through the second passage 16 for a certain period of time (for example, about 30 seconds to 1 minute). As a result, the gas is heated in the second heat accumulator 14, and then heated in the second heater 12, and the heated gas heats the material T to be heated. Here, strong heat can be applied to the left side of the material T to be heated. The gas that has heated the material T to be heated is heated when passing through the first heater 11, and then exchanges heat in the first heat accumulator 13, and is returned to the second fan 26 through the second passage 16.

[0049] In this way, by circulating the gas alternately through the first circulation path P1 and the second circulation path P2, it is possible to effectively heat the entire material T, including the right and left parts. This also makes it possible to effectively agitate the gas inside the furnace body 10, so that the material T can be subjected to a more effective heat treatment.

[0050] In addition, in this electric furnace 1, the first fan 25 and the second fan 26 are provided outside the furnace body 10, so that it is possible to avoid the influence of the heat of the furnace body 10. Therefore, it is possible to reduce damage to the first fan 25 and the second fan 26 and to extend their lifespan.

[0051] In addition, air or an atmospheric gas other than air can be used as the gas in the first and second embodiments. If air is used, the cost of materials used for heating can be reduced and heating efficiency can be improved.

[0052] As the atmospheric gas other than air, various gases can be used, and by selecting a gas suitable for heating the material T to be heated, the heating efficiency can be increased. For example, exothermic converted gas (lean) (DX(L)), exothermic converted gas (rich) (DX(R)), exothermic converted gas (dry) (DX(DRY)), nitrogen converted gas (Nx), endothermic converted gas (RX), endothermic converted gas (SRX), ammonia decomposition gas (AX), HN mixed gas (HN), hydrogen gas, argon gas, nitrogen gas (liquefied gas), and nitrogen gas (PSA gas) can be used. For example, exothermic converted gas (lean) is suitable for blueing steel / oxygen-free annealing of steel and aluminum, while exothermic converted gas (rich) is suitable for bright annealing of low carbon steel / brazing of low carbon steel / annealing of electrical steel sheets. [Explanation of symbols]

[0053] 1 Electric furnace 10 Furnace body 11 First heater 12 Second heater 13 First heat storage device 14 Second heat storage 15 First aisle 16 Second aisle 20 Blower fan 20a outlet 20b Suction port 21 First shutoff valve 22 Second shutoff valve 23 Third shutoff valve 24 Fourth opening and closing valve 25 First Fan 26 Second Fan 30 Furnace body 31 Metal heater 32 Rotating Fan 40 Furnace body 41 Air heater K1 First connecting pipe K2 Second connecting pipe P1 First circulation route P2 Second circulation route T Heated material X Connection position Y connection position

Claims

1. An electric furnace that uses electricity as a heat source and circulates gas inside the furnace body to heat the material to be heated, A first heater provided on one side of the inside of the furnace body in the left-right direction and configured to heat the gas; A second heater provided on the other side of the inside of the furnace body in the left-right direction and configured to heat the gas; A first heat accumulator provided on one side of the outside of the furnace body in the left-right direction and communicating with the first heater; A second heat accumulator provided on the other side of the outside of the furnace body in the left-right direction and communicating with the second heater; a first passage and a second passage separately communicating with the first heat accumulator and the second heat accumulator, respectively, outside the furnace body; a blower fan connected to both the first passage and the second passage and capable of blowing the gas sucked from the second passage side to the first passage side; a first on-off valve provided in the first passage between a connection position of the blower fan and the first heat accumulator; a second on-off valve provided in the first passage between a connection position of the blower fan and the second heat accumulator; a third on-off valve provided in the second passage between a connection position of the blower fan and the first heat accumulator; a fourth on-off valve provided in the second passage between a connection position of the blower fan and the second heat accumulator, This electric furnace is characterized in that by alternately switching the open / closed states of the first on-off valve and the fourth on-off valve and the open / closed states of the second on-off valve and the third on-off valve between opposite states at regular intervals, the gas is alternately circulated through a first circulation path that sends the gas from the blower fan through the first passage to the first heat accumulator, and from the second heat accumulator through the second passage to the blower fan, and a second circulation path that sends the gas from the blower fan through the first passage to the second heat accumulator, and from the first heat accumulator through the second passage to the blower fan, thereby alternately sending the heated gas from the left and right directions to the material to be heated.

2. An electric furnace that uses electricity as a heat source and circulates gas inside the furnace body to heat the material to be heated, A first heater provided on one side of the inside of the furnace body in the left-right direction and configured to heat the gas; A second heater provided on the other side of the inside of the furnace body in the left-right direction and configured to heat the gas; A first heat accumulator provided on one side of the outside of the furnace body in the left-right direction and communicating with the first heater; A second heat accumulator provided on the other side of the outside of the furnace body in the left-right direction and communicating with the second heater; a first passage and a second passage separately communicating with the first heat accumulator and the second heat accumulator, respectively, outside the furnace body; a first fan provided in the first passage and configured to blow the gas in one direction; a second fan provided in the second passage and configured to blow the gas in the other direction, This electric furnace is characterized in that by alternately rotating the first fan and the second fan for a certain period of time, the gas is circulated alternately through a first circulation path passing through the first passage and a second circulation path passing through the second passage, and the heated gas is sent alternately from the left and right directions to the material to be heated.

3. 3. An electric furnace according to claim 1, wherein the gas is air.

4. 3. The electric furnace according to claim 1, wherein the gas is an atmospheric gas other than air.

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