JP7605494B2 - Electric furnace - Google Patents

Description

The present invention relates to an electric furnace used for heat treating metals and non-ferrous metals.

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.

As an example of such a conventional electric furnace, the one shown in Figures 4 and 5 is known. The electric furnace shown in Figure 4 has metal heaters 31 on the left and right sides inside the furnace body 30, and a rotating fan 32 in the upper center of the furnace body 30. These metal heaters 31 heat the air inside the furnace body 30, and the heated material T is heated by convection of the heated air by the rotating fan 32.

The electric furnace shown in FIG. 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.

JP 2015-137781 A

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

However, there is a need to further improve the heating efficiency of all of these electric furnaces. In other words, the electric furnace shown in Patent Document 1 has a cooling function using a cooling fan, which naturally reduces the heating efficiency.

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 then circulates it with a rotating fan 32, so the agitation effect of the heated air is insufficient, and there are issues with heating efficiency. In addition, the heated air always acts on the material T to be heated from a fixed direction, which causes problems with heating efficiency. These are particularly noticeable when the shape of the material T to be heated is complex.

In addition, the rotating fan 32 in this electric furnace is installed inside the furnace body 30, which is at high temperature, so it is prone to damage such as deformation and vibration due to imbalance of the impeller, and there are also problems with its short lifespan.

In addition, the electric furnace shown in FIG. 5 heats the air outside the furnace body 40 (i.e., air at room temperature) with the air heater 41, and then exhausts the heated air after it acts on the material to be heated T. This means that it is necessary to constantly heat the air at room temperature to the required high temperature. This results in a large energy loss and low heating efficiency.

Therefore, the objective of the present invention is to provide an electric furnace that has excellent heating efficiency and a long fan life.

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 of the interior of the furnace body (10) in the left-right direction 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) outside the furnace body (10);
a blower fan (20) connected to both the first passage (15) and the second passage (16) and capable of blowing the gas sucked from the second passage (16) side to the first passage (15);
a first on-off valve (21) provided between a connection position (X) of the first passage (15) to the blower fan (20) and the first heat accumulator (13);
a second on-off valve (22) provided between a connection position (X) of the first passage (15) to the blower fan (20) and the second heat accumulator (14);
a third on-off valve (23) provided between a connection position (Y) of the second passage (16) of the blower fan (20) and the first heat accumulator (13);
a fourth on-off valve (24) provided between a connection position (Y) of the second passage (16) 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) to the first heat accumulator (13) through the first passage (15), and then from the second heat accumulator (14) to the second passage (16) and then returned to the blower fan (20), and a second circulation path (P2) in which the gas is sent from the blower fan (20) to the second heat accumulator (14) through the first passage (15), and then from the first heat accumulator (13) to the second passage (16) and then returned to the blower fan (20), thereby alternately sending the heated gas from the left and right directions to the material to be heated (T).

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 of the interior of the furnace body (10) in the left-right direction 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) outside the furnace body (10);
a first fan (25) provided in the first passage (15) and configured to blow 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).

The present invention is also characterized in that the gas is air.

The present invention is further characterized in that the gas is an atmospheric gas other than air.

Here, the symbols in parentheses above indicate the corresponding elements or items shown in the drawings and in the detailed description of the invention described below.

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.

In addition, since the heated gas is circulated without being dissipated outside the electric furnace, there is less energy loss and the heating efficiency is superior compared to when external gas is taken in.
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.

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 the first circulation direction through the first passage and the second circulation direction through the second passage, and the heated gas is alternately sent from the left and right directions to the material to be heated, so that high heating efficiency can be obtained. In addition, high heating efficiency can be obtained by circulating the heated gas without dissipating it and by utilizing the heat of the first heat accumulator and the second heat accumulator. In addition, since the first fan and the second fan are provided outside the furnace body, the influence of heat can be avoided and their lifespan can be extended.

In addition, the present invention uses air as the gas, which reduces the cost of materials used for heating and contributes to improving heating efficiency.

Furthermore, since the present invention uses an atmospheric gas other than air as the gas, the heating efficiency can be improved by selecting a gas appropriate for the content of the heating process.

This configuration, in which the open/closed states of the first and fourth valves and the open/closed 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 to the material to be heated, is not described at all in the above-mentioned patent documents.

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. 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. FIG. 4 is a front view showing an electric furnace according to a second embodiment of the present invention. FIG. 1 is a front view showing the configuration of an electric furnace according to a conventional example. FIG. 13 is a front view showing an electric furnace according to another conventional example.

The electric furnace 1 according to the 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 sent 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 sent from left to right inside the furnace body 10.

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 it may be placed in a movable state (rotatable, etc.).

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.

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.

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.

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.

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 passage. By operating the first on-off valve 21, the second on-off valve 22, the third on-off valve 23 and the fourth on-off valve 24, the 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 the symbol X, and the connection position of the blower fan 20 to the second passage 16 is indicated by the symbol Y.

This blower fan 20 has an outlet 20a and an inlet 20b, sends gas from the outlet 20a to the first passage 15, and receives gas from the second passage 16 through the inlet 20b. A first connecting pipe K1 is provided between the outlet 20a and the first passage 15, and a second connecting pipe K2 is provided between the inlet 20b and the second passage 16.

The first on-off valve 21 is provided between the 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 the 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 the 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 the connection position Y of the blower fan 20 to the same second passage 16 and the second heat accumulator 14.

This electric furnace 1 can be operated as follows. That is, this electric furnace 1 circulates 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).

When gas is sent to the first circulation path P1 (from right to left inside the furnace body 10) (see FIG. 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 FIG. 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.

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 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 heat from the right side acts strongly on the material T to be heated.

The gas that has been subjected to the heat treatment on 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 opening/closing 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).

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, passes through the second opening/closing valve 22, and reaches 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 exposed to heat from the left.

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, exchanges heat with the first heat accumulator 13, passes through the second passage 16, passes through the third opening/closing 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).

With the electric furnace 1 configured in this way, strong heat can be applied alternately to the material T from the right and left directions, while 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 the gas inside the furnace body 10 can be effectively agitated. Therefore, the material T can be heated more evenly throughout.

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 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.

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.

This electric furnace 1 also uses electricity as a heat source and is configured to heat the material T by circulating gas inside the furnace body 10, 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.

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.

The first heat storage device 13 is provided on the right side of the outside of the furnace body 10 and is connected to the first heater 11. The second heat storage device 14 is provided on the left side of the outside of the furnace body 10 and is connected to the second heater 12. The first heat storage device 13 and the second heat storage device 14 each contain a heat storage material capable of storing heat.

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.

The first fan 25 is provided approximately in 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 approximately in 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.

This electric furnace 1 can be operated by rotating the first fan 25 and the second fan 26 alternately 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 as it passes 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.

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 storage device 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 heated the material T to be heated is heated as it passes through the first heater 11, then exchanges heat in the first heat storage device 13, and is returned to the second fan 26 through the second passage 16.

In this way, by alternately circulating the gas through the first circulation path P1 and the second circulation path P2, the entire material T, including the right and left portions, can be effectively heated. 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.

In addition, in this electric furnace 1, the first fan 25 and the second fan 26 are installed outside the furnace body 10, so that the effects of heat from the furnace body 10 can be avoided. Therefore, damage to the first fan 25 and the second fan 26 can be reduced, and their lifespan can be extended.

In the first and second embodiments, air or an atmospheric gas other than air can be used as the gas. Using air can reduce the cost of materials used for heating and contribute to improving heating efficiency.

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 improved.
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.

REFERENCE SIGNS LIST 1 electric furnace 10 furnace body 11 first heater 12 second heater 13 first heat accumulator 14 second heat accumulator 15 first passage 16 second passage 20 blower fan 20a discharge port 20b suction port 21 first on-off valve 22 second on-off valve 23 third on-off valve 24 fourth on-off valve 25 first fan 26 second fan 30 furnace body 31 metal heater 32 rotary fan 40 furnace body 41 air heater K1 first connecting pipe K2 second connecting pipe P1 first circulation path P2 second circulation path T material to be heated X connecting position Y connecting position

Claims (4)

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. 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 alternately circulated 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 alternately sent from the left and right directions to the material to be heated. An electric furnace according to claim 1 or 2, characterized in that the gas is air. The electric furnace according to claim 1 or 2, characterized in that the gas is an atmospheric gas other than air.

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