JP3766630B2 - Brick holding structure for corner of rotary floor furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure for preventing corner bricks provided at side edges of a hearth of a rotary bed furnace from coming into contact with a side wall of the rotary bed furnace and preventing the rotation of the hearth.
[0002]
[Prior art]
As a method of producing reduced iron by treating dust, scales, sludge, etc., including fine iron ore and iron generated in steelworks, etc., a heated floor furnace (hereinafter referred to as “rotary bed furnace”) ")" Is attracting attention. In this method, in general, an agglomerated mixture of powdered iron oxide raw material and powdered reducing agent is spread on the rotary hearth surface of the rotary bed furnace, and the agglomerate is moved in the floor furnace. Heat reduction is performed to obtain reduced iron.
[0003]
FIG. 3 is an example of a process for producing reduced iron performed using a rotary bed furnace. FIG. 4 shows an overview of the rotary bed furnace. An example of producing reduced iron by a rotary bed furnace will be described with reference to the drawings as follows. As shown in FIG. 3, powdered iron ore, dust, scale, sludge, dust generated in the process of producing stainless steel, powder, iron oxide raw materials such as scale, sludge, etc. and powdered coal are mixed and further mixed with a kneader. Etc. are added and mixed. This mixed raw material is agglomerated by a granulator such as a pelletizer or a double roll compressor. Usually, this agglomerate is dried by a drier to adjust the water content. After drying, the agglomerate is transferred to the raw material charging section of the rotary bed furnace 1 and charged into the furnace. The agglomerate 2 is sent to a rotary bed furnace by a belt conveyor or the like, and from there is charged using a charging chute 12 or the like so as to be widely dispersed on the rotary hearth, and leveled by a leveler or the like. During one rotation accompanying the movement of the rotary hearth, the iron oxide in the agglomerate 2 is reduced to high temperature to form solid metallic iron. The obtained metallic iron is taken out from the discharge part.
[0004]
In the rotary bed furnace 1, an in-furnace temperature of about 900 to 1400 ° C. is secured by sending fuel gas and air into the furnace and burning them. The agglomerate 2 is laid on the hearth 5 of the rotary bed furnace with a thin thickness of about 10 to 20 mm, and the temperature is raised to 900 ° C. or more mainly by a gas burner from the side walls (inner wall 101 and outer wall 102) of the furnace. Then, while the hearth 5 is rotated once, reduction sintering is performed while adjusting the rotation speed of the hearth so as to reach a predetermined metalization rate, and a scraping device such as a screw conveyor 11 (also referred to as a screw feeder) is discharged from the discharge unit. The agglomerate 2 reduced by is discharged.
[0005]
[Problems to be solved by the invention]
Corner bricks may be provided between the hearth and the rotary bed furnace at the side edge of the hearth of the rotary bed furnace. The side edge of the hearth has a side edge near the inner wall 101 and a side edge near the outer wall 102. In a rotary floor furnace provided with corner bricks, as shown in FIG. 5, it is common to provide corner brick 3x near the outer wall and corner brick 3y near the inner wall. The corner bricks are provided mainly for the purpose of restraining the free expansion of the hearth material and preventing the hearth from contacting the side wall. Moreover, when performing the reduction process in a rotary bed furnace, it is common to place a rug called a hearth material such as iron ore and refractory on a hearth substrate 50 such as an iron plate. The hearth materials 51, 52 and 53 are laid for the purpose of protecting the hearth substrate 50 and facilitating removal of the fusion material accumulated in the hearth (FIG. 6).
[0006]
In a rotary bed furnace, the inside is heated by a gas burner or the like. In the case of reduction of iron oxide, the inside of the rotary bed furnace is heated to about 900 to 1400 ° C. When the operation of the rotary bed furnace is continued for a while, the corner bricks provided on the side edges of the hearth are pressed in the radial direction by the thermal expansion of the hearth material, and the corner bricks are applied to the side walls of the rotary bed furnace. Contact and hinder the rotation of the hearth. In particular, the outward pressure tends to increase. If a specific example is given, a corner part brick will fall in diameter outward, will contact an outer wall, and will stop rotation of a floor furnace (FIG. 6).
[0007]
Stopping the rotation of the hearth in a rotary bed furnace means that the operation stops, which is a very important problem. When the corner brick portion comes into contact with the side wall and the hearth floor stops rotating, it must be repaired each time, which causes a decrease in operation efficiency.
[0008]
The present invention suppresses that the corner brick is pressed in the radial direction by the thermal expansion of the hearth material provided in the hearth and presses the side wall of the rotary floor furnace via the brick, thereby preventing the rotation of the hearth. It is an object of the present invention to provide a structure to perform.
[0009]
[Means for Solving the Problems]
The present invention focuses on the mechanism of hearth material expansion, the structure of the hearth, particularly the structural relationship between the hearth material and the corner brick, in order to suppress contact with the side wall of the corner brick. For this purpose, the following measures were adopted.
(1) In a rotary bed furnace used for heat treatment, the hearth of the rotary bed furnace is formed by laying a plurality of layers of a hearth material on a hearth substrate, and is provided below the uppermost layer. An inclined refractory material that is inclined upward toward the radial side edge side of the hearth and disperses the horizontal force generated by the thermal expansion of the hearth material upward is provided on the side edge of the hearth. A corner brick holding structure that disperses the radial pressing force of the corner brick installed in the corner.
(2) the hearth is formed by laying a hearth material a plurality of layers on a hearth substrate, a second layer of hearth material from the top, according to a powdery refractory (1) the corner brick retaining structure.
(3) In the rotary bed furnace used for the heat treatment, the thermal expansion of the hearth material laid on the hearth resists the force that presses the corner bricks installed on the side edges of the hearth in the radial direction. And having a pressure-resistant means for holding the corner brick, and the pressure-resistant means is a corner brick collapse prevention plate provided on a surface of the installation base on which the corner brick is installed with respect to the hearth inner side. Corner part brick holding structure as described in 1).
(4) the hearth the circumferential length of the corner bricks are placed on the side edges of, in the circumferential angle 10 ° or more in length of the rotating bed furnace, restrain the falling over corner brick The corner part brick holding structure as described in (1) .
(5) A rotary bed furnace having the corner brick holding structure according to any one of (1) to (4 ).
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the corner brick is held so as to suppress that the hearth material constituting the hearth is thermally expanded and presses the corner brick to contact the side wall to prevent the hearth from rotating. Holding the corner bricks means keeping the corner bricks from contacting the side walls. Specific examples of the holding include holding the corner brick so as not to be shifted laterally so as to approach the side wall, holding the corner brick so as not to fall down, and the like. A more specific embodiment of the holding structure of the present invention is a structure in which the present invention relates to a corner brick, a structure in which the horizontal force generated by the expansion of the hearth material is released upward, and the expansion of the hearth material is suppressed. The structure is embodied in the form of a structure that stabilizes the corner brick itself. Hereinafter, each embodiment of the present invention will be described sequentially with reference to the drawings. FIG. 1 shows a plan view (a) and a sectional view (b) of the rotary bed furnace. FIG. 2 shows an enlarged view of a part of FIG. 5 and 6, the corner brick 3A is installed near the outer wall 102 of the rotary floor furnace, and the corner brick 3B is installed near the inner wall 101. 5 and 6, iron ore 55, powder refractory 56, refractory 57, and refractory 58 are laid on an iron plate 50 as a hearth substrate in order from the top layer.
[0011]
[First Embodiment] Installation of Inclined Refractory Material As a first embodiment, on the side edge of the hearth material laid below the uppermost hearth material, on the radial side edge side of the hearth An inclined refractory material inclined upward is provided. This inclined refractory material changes the thermal expansion direction of the hearth material upward and disperses the horizontal force generated by the thermal expansion upward. By providing the inclined refractory material, the force of pressing the corner brick against the side wall can be weakened, and the corner brick can be prevented from falling and coming into contact with the side wall. Toward the radial side edge means that the side edge near the outer wall faces outward in the radial direction, and on the other hand, the side edge near the inner wall faces toward the radially inner side. The inclination angle α of the inclined refractory material is preferably 5 to 30 °, particularly preferably about 15 °. The inclined refractory material may be provided in any part of the hearth material laid below the uppermost layer as long as the thermal expansion of the hearth material can be released upward, but preferably the uppermost hearth material. It is preferable that the inclined surface is in contact with the uppermost hearth material.
[0012]
In the example shown in FIG. 2, the inclined refractory material 7 is provided on the refractory 57. The inclined surface 7a of the inclined refractory material 7 is inclined upward and radially outward with respect to the refractory 57 at an angle of α = 15 °. The slope 7a of the inclined refractory material 7 is covered with an iron ore 55 that forms the uppermost layer. The iron ore 55 expands in the direction of the arrow due to thermal expansion, but is guided in the upper right direction in FIG. 2 by the inclined refractory material 7.
[0013]
[Second Embodiment] Laying Powdery Refractory In the second embodiment, powdery refractory is used as the second-layer hearth material from the top. As the powder refractory, an alumina pole is preferably used. By interposing a powder refractory in the layer below the uppermost layer that is most likely to be thermally expanded, it is possible to mitigate the fact that the uppermost hearth material is fused by heat and thermally expanded. The size of the powder refractory is preferably a particle size of 1 to 50 mm, particularly preferably a particle size of 5 to 30 mm.
[0014]
FIG. 2 is an enlarged view of a part of FIG. In the example shown in FIGS. 1 and 2, various hearth materials are laminated in order from the top layer. In FIGS. 1 and 2, iron ore 55, alumina pole 56, refractory 57, and refractory 58 are spread on iron plate 50 in order from the top layer. The alumina pole 56 is a powder refractory, whereas the refractory 57 and the refractory 58 are regular refractories or irregular shapes.
[0015]
[Third Embodiment] Installation of anti-pressing means In the third embodiment, anti-pressing means is provided so as to resist horizontal force generated by thermal expansion of the hearth material.
[0016]
An L-shaped pedestal 41 as shown in FIG. 2 is generally used as an installation pedestal provided with corner bricks because of the ease of work for positioning the corner bricks on the installation pedestal and the ease of positioning. Thus, when the L-shaped installation base 41 is initially provided, the corner part bricks are prevented from falling by installing the corner part fall prevention plate 43 on the surface with respect to the inner side of the hearth. be able to. More specifically, the surface facing the inside of the hearth is a surface facing radially inward at the side edge near the outer wall 102, and a surface facing radially outward at the side edge near the inner wall 101. is there. In the case where an L-shaped installation base is initially provided, it is cheaper to retrofit the corner brick fall prevention plate as described above than to replace the entire corner brick installation base. The work is also simple.
[0017]
On the other hand, an installation base 41 having a groove from the beginning may be provided, and a corner brick may be provided in the groove.
[0018]
[Fourth Embodiment] Preparation of Brick Circumferential Length In the fourth embodiment, the circumferential length of the corner brick is set to 10 ° or more. By setting the circumferential length to a circumferential angle of 10 ° or more, the stability of the corner brick with respect to the force applied in the radial direction is improved. The circumferential length is not particularly limited from the viewpoint of the stability of the corner brick, but is limited to about 20 ° from the viewpoint of ease of installation work of the corner brick and the absorption of thermal expansion in the circumferential direction. It is preferable that
[0019]
In the example shown in FIG. 1, each of the corner bricks 3A and 3B has a circumferential length of 10 ° in the circumferential angle. The circumferential length only needs to be 10 ° or more in terms of the circumferential angle, and as is clear from the example shown in FIG. 1, the absolute length of the circumferential length between the corner brick near the inner wall and the corner brick near the outer wall is clear. The length may be different.
[0020]
The first to fourth embodiments described above may be implemented independently, may be applied in combination with one another, or may be applied entirely. In order to suppress the situation where the corner bricks come into contact with the side walls and prevent the hearth from rotating, and to perform continuous operation of the rotary hearth, it is particularly preferable to apply all of the first to fourth embodiments. Is preferred.
[0021]
Further, the holding structure of the present invention may be applied to only one of the side edge portion near the inner wall 101 and the side edge portion near the outer wall 102 of the hearth of the rotary bed furnace, or may be applied to both side edge portions. Good. It is more preferable that it is provided on both side edges in that it does not hinder the rotation of the hearth, rather than either one. However, if only one of them is used to reduce the installation cost, etc., the furnace material on the hearth base plate usually tends to expand to a larger diameter outward, so the side edge near the outer wall. It is more preferable to apply the structure of the present invention to the above.
[0022]
The application of the corner brick holding structure of the present invention is not limited to the use of a rotary bed furnace. That is, the corner part brick holding structure of the present invention can be suitably used not only for a rotary bed furnace for reducing iron oxide but also for a rotary coil furnace for annealing a batch coil, for example.
[0023]
【The invention's effect】
According to the present invention, the corner brick provided on the side edge of the hearth is pressed in the radial direction by the thermal expansion of the hearth material and the corner brick contacts the side wall of the rotary floor furnace, Stopping rotation of the floor can be suppressed. Therefore, according to the present invention, the continuous operation time of the rotary bed furnace can be extended. Furthermore, since the cost of repairing the damage to the rotating bed furnace caused by the contact between the corner brick and the outer wall can be greatly reduced, it contributes to reducing the running cost of the rotating bed furnace.
[Brief description of the drawings]
FIG. 1 is a plan view (a) and a sectional view (b) of a rotary bed furnace.
FIG. 2 is a diagram showing an embodiment of a corner brick holding structure.
FIG. 3 is a diagram showing an example of a process for producing reduced iron using a rotary bed furnace.
FIG. 4 is a view showing an overview of a rotary bed furnace.
FIG. 5 is a plan view (a) and a sectional view (b) of a rotary bed furnace.
FIG. 6 is a diagram illustrating a state in which a corner brick is collapsed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rotary bed furnace 101 ... Inner wall 102 ... Outer wall 103 ... Gas burner flame 104 ... Gas burner and air introduction machine 11 ... Screw conveyor 12 ... Charging chute 13,14 ... -Partition wall 2 ... Agglomerates 3A, 3B, 3x, 3y ... Brick 4, 4 '... Installation base 41 ... Installation base 42 ... Base column 43 ... Corner part Brick collapse prevention plate 5 ... hearth 50 ... iron plate (hearth substrate)
51, 55 ... hearth material (first layer)
52, 57 ... Refractory (2nd layer)
53, 58 ... Refractory (3rd layer)
56 ... Powdered refractory 7 ... Inclined refractory material

Claims (5)

  In the rotary bed furnace used for heat treatment, the hearth of the rotary bed furnace is formed by laying a plurality of layers of the hearth material on the hearth substrate, and the side edge of the hearth material provided below the uppermost layer Is provided with an inclined refractory material that inclines upward toward the radial side edge of the hearth and disperses the horizontal force generated by the thermal expansion of the hearth material upward, and is installed on the side edge of the hearth A corner brick holding structure that disperses the radial pressing force of the corner brick. The corner portion according to claim 1, wherein the hearth is formed by laying a plurality of layers of a hearth material on a hearth substrate, and the hearth material of the second layer from the top is a powder refractory. Brick holding structure. In the rotary bed furnace used for the heat treatment, the corner against the force of pressing the corner bricks installed on the side edge of the hearth in the radial direction by the thermal expansion of the hearth material spread on the hearth. It has anti pressing means for holding the parts bricks, antibody pressing means is a prevention plate fall corner brick provided on the surface with respect to the installation base of the hearth inner corner bricks are installed, according to claim 1 Corner brick holding structure. The circumferential length of the corner bricks are placed on the side edge of the hearth, and the circumferential angle 10 ° or more in length of the rotating bed furnace, inhibiting claim that the corner brick falls down 1 The corner brick holding structure described in 1 . A rotary bed furnace comprising the corner brick holding structure according to any one of claims 1 to 4 .

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