JPH09138078A - Arc furnace - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To improve the thermal efficiency and energy saving when arc melting a molten material in an arc furnace, and further improve the operating efficiency of the arc furnace so that the productivity can be enhanced. SOLUTION: A plurality of storage containers for melting raw materials are communicated with the furnace body, and high-temperature exhaust gas discharged during melting of the melting raw materials is passed through the storage containers to preheat the melting raw materials in the storage containers. Each storage container is configured so that it can be installed and removed in a state in which it communicates with the furnace body, and the storage container that has been emptied by charging the melting raw material into the furnace body is replaced with a storage container that is filled with the melting raw material in advance It can be so.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention can save energy by heating a melting raw material to melt it and recovering the heat of exhaust gas generated at that time by preheating the melting raw material to be melted next. About the arc furnace.

[0002]

2. Description of the Related Art As an arc furnace of this type, a melting material is charged into each of the above-mentioned charging ports in a furnace body which is provided with two charging ports for charging the melting materials. Electrodes for generating an arc are attached between the two locations, and two storage tanks for the melted raw materials, each of which has a raw material outlet on the lower side, are provided above the respective inlets. There is an arc furnace that is arranged in such a manner that and the delivery port of each storage container communicate with each other.

In the above-mentioned arc furnace, when the molten raw material is heated by arc in the furnace body, an arc can be generated between the molten raw materials charged from the both charging inlets, so that the furnace wall is provided on both sides of the arc. It becomes a shadow of the above-mentioned melting raw material, heat loss through the furnace wall can be reduced by that much, and thermal efficiency can be improved. Moreover, in the case of the arc heating, the high temperature exhaust gas generated by the melting can be passed through each storage container and the next melting raw material stored therein can be preheated, so that the preheated melting is performed at the next melting in the furnace body. By using the raw material, heat can be recovered and energy can be saved. Further, when the preheated molten raw material is charged into the furnace body, the preheated molten raw material in the storage container can be dropped directly into the furnace body A, so that charging can be performed with less heat loss.

[0004]

However, in the above-mentioned conventional arc furnace, after the molten steel melted in the furnace body is tapped and the molten raw materials preheated in the two storage containers are charged into the furnace body, When trying to perform the arc heating again in the preheatable state of the molten material of the next time as described above, first of all, it is necessary to fill the two storage containers with the molten material of the next time, Since it was necessary to wait for the resumption of arc heating during the filling operation, the operating efficiency of the arc furnace was limited, and there was a problem of impairing productivity.

The arc furnace of the present invention is provided to solve the above-mentioned problems of the prior art. An object of the present invention is to reduce the heat loss through the furnace wall by the melting raw material when arc heating the melting raw material in the furnace body, and to improve the thermal efficiency.
Another object is to recover the heat of the exhaust gas in the case of the above-mentioned arc heating by preheating the melting raw material next time by the exhaust gas, thereby making it possible to achieve energy saving. Another object is to allow the preheated melted raw material to be charged into the furnace without heat loss. The other purpose is
After the steel is tapped from the furnace body and the molten raw material that has been preheated in the storage container is charged into the furnace body, the next molten raw material can be preheated immediately by performing the work that requires an extremely short time, only replacing the storage container. In this state, it is possible to start arc heating in such a state that the operating efficiency of the arc furnace can be improved and productivity can be increased. Other objects and advantages will be more readily apparent from the drawings and the following description associated therewith.

[0006]

In order to achieve the above object, the arc furnace according to the present invention has a furnace body having a plurality of charging ports for charging the molten raw materials in the upper part thereof. In the above, an electrode for generating an arc is provided between the charging inlets and the places where the molten raw materials are charged, and the raw material outlets are provided on the lower side above the charging inlets. A plurality of storage containers for dissolved raw materials are arranged in a state in which the inlets and outlets of the storage containers are in communication with each other, and exhaust gas discharged from the inlets is passed through the storage container and stored therein. In an arc furnace that preheats the molten raw material in the container and allows the preheated molten raw material to be charged into the furnace body from the charging port, each storage container is installed in the upper position and It can be configured to be removed freely, The storing container emptied by charging the solution raw material is removed from the upper position and at the same exchange to,
The storage container pre-filled with the dissolution raw material can be installed at the upper position.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The drawings showing the embodiments of the present invention will be described below. 1 to 3 showing a DC arc furnace as an example of the arc furnace, A indicates a furnace body for melting the melting raw material. 1 is the bottom of the furnace body A, 2
Is the wall of the furnace, 3 is the boundary between the two, 4 is the top of the furnace, and the symbols 4a,
The portion indicated by 4b is formed in a cylindrical shape for guiding exhaust gas discharge. Reference numerals 5a and 5b denote inlets for melting raw materials, and the cylindrical portion
It is configured with openings at the upper ends of 4a and 4b. The charging ports 5a and 5b also serve as ports for discharging exhaust gas. 6 is an auxiliary exhaust port for auxiliary discharge of exhaust gas in the furnace body,
It is provided on the side wall of one tubular portion 4b. Reference numeral 7 denotes a space for melting the raw materials in the furnace body A. In FIG. 3, 8 is a furnace bottom electrode, 9 is a tap hole, and an opening / closing device 10 is provided. Figure 1
Reference numeral 11 shown in FIG. 3 is an electrode for generating an arc, which is a position in the furnace body A where the molten raw material is charged from each of the charging ports 5a and 5b, that is, a position directly below each charging port 5a and 5b in this example. In order to generate an arc between them, the furnace top 4 is provided, for example, between the cylindrical portion 4a and the cylindrical portion 4b. Reference numeral 12 denotes a supporting arm that supports the electrode so that the electrode can move up and down, and 13 denotes a bush for electrical and thermal insulation between the electrode and the furnace body A, respectively. Reference numerals 16a and 16b denote dampers for switching the discharge of exhaust gas from the charging ports 5a and 5b and the stop thereof. By moving forward and backward in the direction of arrow 17, the dampers retreat as shown by the solid line to open the charging port or the two-dot chain line. As shown in FIG. 3, the charging port is located at the charging port and is closed, or the intermediate position between them is adjusted so that the amount of exhaust gas passing through the charging port can be adjusted. These dampers are driven by, for example, an air cylinder (not shown). Reference numeral 18 attached to the furnace wall 2 indicates a burner for performing auxiliary heating for promoting melting.

Next, B1, B2, and B3 represent storage containers for storing the molten raw material for preheating. All of these storage containers have the same configuration. The melting raw material is called scrap, for example. Reference numeral 21 in the storage container indicates an inlet for the dissolved raw material, and is provided on the upper side of the storage container so that the received dissolved raw material can reach the internal storage chamber 26 by its own weight. For example, it has an opening at the upper end. The receiving port 21 is also a gas delivery port for delivering the exhaust gas that has been used for preheating. Reference numeral 22 denotes an outlet for the dissolved raw material, which is provided on the lower side of the storage container so that the dissolved raw material in the storage container can be delivered by its own weight. For example, it has an opening at the lower end. The outlet 22 is also a gas inlet for receiving exhaust gas for preheating. 24 is an annular covering member provided around the outlet 22 for preventing the leakage of exhaust gas.
When the 22 is superposed on the charging openings 5a, 5b, the members 5a ', 5b' on the periphery of the charging openings 5a, 5b can be mounted, for example, on the upper ends of the tubular portions 4a, 4b of the furnace top in this example. It is provided around the outlet 22 of the container so as to be vertically movable. Reference numeral 25 denotes a holding means for holding the dissolved raw material in the storage containers B1 to B3, which is openable for delivering the retained dissolved raw material. A space up to the receiving port 21 above the holding means 25 is a scrap storage space 26. The volume of the storage space 26 is designed in accordance with the melting capacity of the furnace body A (for example, 80 to 90 tons per charge), and has a size capable of storing approximately half of the melting raw material. The holding means 25 has air permeability for circulating the exhaust gas received from the outlet 22 into the storage space 26. For example, it is formed like a cage. The opening can be performed by rotating the storage container from the outside around the shaft portion 25a in the direction of the arrow. Reference numeral 27 is a wheel provided on the outer surface of the storage container to enable the movement of the storage container.

Next, C shows an exhaust passage for sending the exhaust gas after being used for preheating to the next stage. 31a, 31b in the exhaust passage
Is a hood for preventing leakage of exhaust gas, and openings at the lower ends of the hoods are gas inlets 31a 'and 31b'. Reference numeral 32 denotes a cover member for preventing the exhaust gas from leaking out between the hood and the storage container when the reception port 21 of the storage container is superposed on the gas reception ports 31a 'and 31b'. It is provided around 31a 'and 31b' so that it can move up and down, and the receiving port in the storage container
The members around 21 are mounted on the upper edge of the storage container in this example. 33 and 34 are ducts for sending exhaust gas to the next stage, and 35 is a cooling device for exhaust gas. 36a, 36
Reference numerals b and 37 respectively denote dampers for turning on and off the flow of gas through the inlets 31a ', 31b' and the auxiliary exhaust port 6 and controlling the flow rate.

Next, D shows an exchange means for exchanging the storage container in the loaded state with respect to the furnace body A. The loaded state means that the delivery port 22 of the storage container communicates with the loading port 5a or the loading port 5b of the furnace body A, and the receiving port 21 is the receiving port 31a 'or the receiving port 31b'.
The exhaust gas from the furnace body reaches the exhaust passage C through the inside of the storage container, and the molten raw material in the storage container is sent out from the outlet 22 and charged into the furnace body A through the charging ports 5a and 5b. Say that you are able to do. Pa and Pb indicate the loading locations where the storage container is loaded into the furnace body A above the charging ports 5a and 5b, respectively. The exchanging means D is configured such that each of the storage containers B1 to B3 has a loading place Pa at which the outlet 22 and the receiving inlet 21 are in communication with the loading inlet 5a and the receiving inlet 31a ′, or the sending outlet 22 and the receiving inlet 21. Entrance 5b and reception 31 respectively
This is for installation at the loading place Pb which is in communication with b'and for removal from those places.
As an example of the means D, in this example, the storage container is approached to the above-mentioned loading places Pa, Pb from the side thereof and held at each of the loading places Pa, Pb, and The structure is shown so that it is possible to exit from the locations Pa and Pb in the lateral direction. The purpose of the entry from the lateral side and the exit to the lateral side is to provide a work space for the installation work of the storage container at the loading place and the removal work from the storage container of the storage container at the loading place. This is because it is not necessary to secure it above, and the arc furnace can be installed in a relatively low building.

In this example, the means D is an example in which the storage container can be moved between the loading locations Pa and Pb and the preparation location Pc different from them. The preparation place Pc is a place for preparing a storage container filled with a melting raw material.
The storage container may be filled with the dissolved raw material at the preparation place Pc, or may be filled at another place and the filled storage container may be brought to the preparation place Pc. Above loading place
In order to allow the storage container to enter and leave Pa and Pb, the above-mentioned means D is constituted by members 41-49. That is, 41 is a fixed frame for supporting the storage container, 42 is a rail for enabling horizontal movement of the storage container, which is laid on the fixed frame 41, on which wheels 27 of the storage container are placed. The rolling of the storage container makes it possible to move the storage container. 43 is a base that serves as a base for moving a carriage 45 described below, 44 is a rail laid thereon, and the carriage 45 is in a direction intersecting (for example, orthogonal to) the movement direction of the storage container by the rail 42. It is for making it possible to move. Trolley 45 has wheels 46
And is movable along the rail 44 in the directions of arrows 47a and 47b, and rails 48 and 49 are laid on the upper surface. In addition, 51 provided in the preparation place Pc is a frame for supporting the storage container in the preparation place Pc, and 52 is a rail.

In the above DC arc furnace, by passing a direct current through the arc generating electrode 11 and the furnace bottom electrode 8, an arc 11a is generated from the electrode 11 as shown in FIG. The charged molten material G is the arc 11
It is heated and melted by the heat of a. In the case of the melting, the arc 11a is the melting raw material G charged through the charging ports 5a and 5b.
Is generated between. Therefore, the melting raw materials G located on both sides of the arc 11a cause the furnace walls 2a and 2b of the portions located outside the melting raw materials G to be in a state of being shaded with respect to the arc 11a. As a result, it is difficult for the high heat of the arc 11a to be transmitted to the furnace walls 2a and 2b in the shadowed areas. Therefore, the heat loss through the furnace walls 2a and 2b in those areas is small, and the heat loss of the entire furnace body A can be suppressed. Further, during the arc heating, the high-temperature exhaust gas generated by the melting of the melting raw material G flows into the storage spaces 26 in the upper storage containers B1 and B2 to heat the melting raw material therein. The exhaust gas that has been heated reaches the cooling device 35 through the hoods 31a and 31b and the duct 33, and the exhaust gas that exits the cooling device 35 is sent to a dust collector (not shown).

Next, a series of operations of the arc furnace will be described with reference to FIG. First, as shown in (A), two storage containers
The melting raw material G in B1 and B2 is charged into the furnace body A through charging ports 5a and 5b. The melting raw material G was preheated during the previous melting in the furnace body A. The time required for the charging operation is, for example, 1 to 2 minutes. Next, as shown in (B), the one empty storage container B1 is removed from the loading place Pa,
In exchange therewith, the storage container B3, which is filled with the melting raw material G in advance, is installed at the loading place Pa. Further, the damper 16b is closed to prevent the exhaust gas from flowing out from the charging port 5b.
The time from the completion of the above charging to this time is, for example, 2 to 3
Minutes.

Next, the arc heating in the furnace body A is started.
That is, as shown in (C), the arc 11a is generated from the electrode 11 by energizing the electrode 11, and the arc 11a causes the furnace body A to
The operation of heating the melting raw material G therein to melt it is started. During the arc heating, the high-temperature exhaust gas generated by the melting of the melting raw material is charged at the loading place as shown by an arrow 71.
The molten raw material that flows inside the storage container B3 in Pa and is stored therein is heated, and then goes to the exhaust passage C. While the arc heating is being performed in the furnace body A, the removed empty storage container B1 is carried to the preparation place Pc and the melting raw material G is filled. The time required for these operations is 1
0 minutes.

When the loading of the melting raw material G into the storage container B1 is completed, the empty storage container B2 at the loading place Pb is removed as shown in (D), and in exchange therewith, the melting raw material G is loaded. The filled storage container B1 is installed at the loading place Pb. Then, the damper 16b is opened. Then, the high-temperature exhaust gas also flows into the storage container B1 as shown by the arrow 72, and heats the melting raw material G there.

In the above state, arc heating is continued,
As shown in (E), all the melting raw materials in the furnace body A are melted. Meanwhile, in the meantime, the removed empty storage container B2 is carried to the preparation place Pc, and the melting raw material G is filled therein. (E)
When the melting of all the molten raw materials is completed as described above, the molten steel M and the slag S floating on the molten steel M as shown in FIG. 3 are formed. The time from the start of the arc heating to the completion of the melting of all the melting raw materials as described above is, for example, 25.
Minutes.

When the melting of all the melting raw materials is completed as described above, tapping is performed as indicated by an arrow 73 in (F). Then, the furnace body A is repaired. This completes the operation of the arc furnace for one cycle. After that, the work from the above (A) is repeated again. It should be noted that from the start of the tapping, the furnace body A
It takes, for example, about 5 minutes to complete the repair.

Next, (C), (D) and (E) of FIG.
When melting or oxidation due to overheating of the melted raw material in the storage container is expected in the situation shown in, the auxiliary exhaust port 6
It is possible to prevent the above-mentioned melting and oxidation by exhausting the gas and reducing the amount of the exhaust gas reaching the respective storage containers by narrowing down the dampers 16a and 16b. When it is desired to start the arc heating after the state (A) in FIG. 4 and before the state (B) is reached, the both dampers 16a and 16b are closed and the auxiliary exhaust port 6 is used to exhaust the arc so that the arc can be started earlier. The heating can be started. Further, when the number of storage containers that can be prepared in a state in which the melting raw material is filled in advance is equal to or larger than the number of storage containers that are in a loaded state in the furnace body A (for example, 2 in the above example). In addition, it is also possible to replace both the empty storage containers in the stage of FIG. 4B with the filled storage containers.

Next, an example of a method of exchanging the storage container in the loaded state with respect to the furnace body A, for example, the storage container at the loading place Pa by the exchanging means D will be described with reference to FIG. First, the storage container B3 filled with the melted raw material prepared in the preparation place Pc is moved onto the rail 48 of the carriage 45 as indicated by an arrow 61. Next, the carriage 45 is moved in the direction of the arrow 47a so that the rail 49 is connected to the rail 52 and the rail 42 on the loading place Pa side. Next, the empty storage container B1 in the loading place Pa is moved to the preparation place Pc through the rails 42, 49 and 52 as shown by an arrow 62. Next, the carriage 45 is moved in the direction of the arrow 47b so that the rail 48 is connected to the rail 42 on the loading location Pa side.
Next, place the storage container B3 on the rail 48 on the rail 42 as shown by the arrow 63.
Through to the loading location Pa. An example of a method of exchanging the storage container at the loading place Pb is as follows. The storage container at the preparation place Pc is moved onto the rail 48 of the carriage 45, and the storage container at the loading place Pb is moved onto the rail 49.
Next, the carriage 45 is moved in the direction of arrow 47b. And the rail
The storage container on 48 is moved to the loading place Pb through the rail 42 on the loading place Pb side. Next, the carriage 45 is moved in the direction of arrow 47a. Then, the storage container on the rail 49 is moved to the preparation place Pc. Needless to say, the exchange may be performed in an order other than the above order.

Next, in the above embodiment, the entrance and exit paths of the storage container to each loading location are shared (rail 4
In 2), in order to shorten the time required for exchanging the storage container at the loading place, the approach path and the exit path of the storage container to the loading place may be set separately. For example, FIG.
As shown by arrows 74 and 75, an entry path 74 is set on the left side with respect to the loading place Pb, and an exit path 75 is set on the right side, while the empty storage container is exited as shown by the arrow 75, A filled storage container may be entered as indicated by arrow 74.
Further, the means for installing and removing the storage containers at the loading locations is not limited to the exchange means D,
For example, a forklift may be used to install or remove the storage container at each of the loading locations. Furthermore,
In the furnace body A, three or more inlets for melting raw materials are provided,
You may make it arrange | position a storage container above each.

[0021]

As described above, according to the present invention, when the melting raw material G is arc-heated in the furnace body A, a plurality of charging ports are provided.
Since the arc 11a can be generated between the molten raw materials G charged from 5a and 5b, respectively, the respective molten raw materials located on both sides of the arc 11a are arc 11a against the furnace wall.
Make a shadow of. As a result, the furnace wall 2 in the shadowed area
The high heat of the arc 11a is less likely to be transmitted to the furnace, and the heat loss through the furnace wall 2 can be reduced accordingly, and the thermal efficiency can be improved. Moreover, in the case of the arc heating, high temperature exhaust gas generated by melting is stored in a plurality of storage containers.
Next melt raw material G to be stored in each through B1 and B2
Since it can be preheated, the heat can be recovered and energy can be saved by using the preheated melting raw material at the next melting in the furnace body. Further, when the preheated melting raw material G is charged into the furnace body A, the preheated melting raw material in the storage containers B1 and B2 can be directly dropped into the furnace body A, so that the heat loss is reduced. There is an effect that can be entered. Furthermore, steel was tapped from furnace body A,
After charging the melting raw material preheated in the storage containers B1 and B2 into the furnace body A, the empty storage container is removed from a position above the charging port 5a, and the melting raw material is preliminarily charged in exchange therewith. There is a feature that the next melting raw material can be positioned in the passage of the exhaust gas from the furnace body A only by installing the stored storage container at the above upper position. This makes it possible to start the arc heating in the state in which the molten raw material can be preheated next time, as described above, significantly faster than the conventional technique. As a result, there is an effect that the operating efficiency of the arc furnace can be improved and the productivity can be increased.

[Brief description of the drawings]

1 is a vertical cross-sectional view of an arc furnace (enlarged cross-sectional view taken along the line I-I in FIG. 2).

FIG. 2 is a plan view.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4A to FIG. 4F are diagrams for explaining the operating sequence of the arc furnace.

[Explanation of symbols]

 A furnace body B1, B2, B3 storage container

Claims (1)

[Claims] 1. A furnace body having a plurality of charging ports for charging the melting raw materials in an upper portion, an arc is provided between the charging ports in the furnace body where the melting raw materials are respectively charged. An electrode for generating the above, and above each of the charging ports, a plurality of storage containers for the dissolved raw materials each having a raw material outlet on the lower side, in each of the charging ports and each storage container. Arranged to communicate with the delivery port, the exhaust gas discharged from the charging port is passed through the storage container to preheat the melting raw material in the storage container, and the preheated melting raw material is charged into the charging port. In an arc furnace that can be charged into the furnace body from above, each storage container is configured to be installed in the upper position and removed from it freely, and empty by charging the molten raw material into the furnace body. Remove the storage container from the above position and In exchange for this, an electric arc furnace characterized in that a storage container pre-filled with the molten raw material can be installed at the above-mentioned upper position.