JP2001108372A - Rotary hearth furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge device in place of a screw conveyor in a rotary hearth furnace. SOLUTION: A discharge device 2 of a rotary hearth furnace is shaped like a plate and it is tilted at an angle of 10-60 degrees (angle A) to the direction of rotation of a hearth in the vertical direction and at an angle of 10-45 degrees (angle B) to the direction of rotation of the hearth from the center line of the hearth in the horizontal direction. The discharge device 2 is made to be of a rotary type, and it is preferable that discharge openings 6a and 6b are provided at two places, the inner peripheral side and the outer peripheral side of the rotary hearth furnace, and that side walls 3a-3d in the sphere of movement of the discharge device 2 are made to be of a moving type.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a rotary hearth furnace.

[0002]

2. Description of the Related Art In the production of reduced iron by the rotary hearth method described in JP-A-9-310111, 1000
Reduced pellets of ℃ or more are discharged outside the furnace by a screw conveyor. Although the screw conveyor is made of heat-resistant metal, it is difficult to use it for a long time at a high temperature of 1000 ° C or more, and the drive shaft is equipped with a water-cooled pipe to prevent deformation by cooling. Since it is in contact with pellets or briquettes, the current situation is to replace the screw part by replacing it every six months to one year due to thermal deformation and wear. In addition, since the screw conveyor is exposed to high temperatures, it must be constantly rotated to prevent deformation, and an uninterruptible power supply that supplies power and maintains rotation even during a power failure is required. Furthermore, for screw conveyors, the outlet of pellets or briquettes is one outlet.
When transporting pellets or briquettes, it is necessary to switch between buckets. In order to switch the bucket, a movable chute is provided at the exit of the screw conveyor, and the chute is moved by switching the chute to the bucket placed at two places. Therefore, it is necessary to arrange the rotary hearth furnace high, and there is a problem that the basic equipment cost of the rotary hearth furnace increases. There is also a method of switching by moving the bucket, but a bucket moving device is required.

[0003]

In a screw conveyor for discharging pellets or briquettes from a rotary hearth furnace to the outside of the furnace, it is necessary to replace the screw of the screw conveyor, which cannot be water-cooled, due to deformation, wear, and corrosion in a high temperature state. There is. It is conceivable to use an expensive heat-resistant alloy for the screw portion, but the pellet temperature of the rotary hearth 11
At present, it is difficult to withstand long-time use at 00 to 1300 ° C. even if an expensive heat-resistant alloy is used. In addition, an uninterruptible power supply that rotates the screw conveyor during a power outage is required, and there is only one outlet, so a rotary hearth furnace for switching pellets or briquette buckets is installed at a higher position, A bucket moving device is required.

Accordingly, it is an object of the present invention to provide a pellet or briquette discharge device that replaces a screw conveyor with simple equipment, and avoids increasing the height of a rotary hearth furnace, or provides a bucket moving device. It is unnecessary.

[0005]

The present invention is as follows.

(1) A discharge device for pellets or briquettes of a rotary hearth furnace is formed in a plate shape, and the discharge device is inclined 10 to 60 degrees in the direction of rotation of the hearth in the vertical direction, and the center of the hearth in the horizontal direction. A rotary hearth furnace characterized by being installed at an angle of 10 to 45 degrees in the direction of rotation of the hearth from the line.

(2) The rotary hearth furnace according to (1), wherein the discharge device is a rotary type, and discharge ports are provided at two locations on an inner peripheral side and an outer peripheral side of the rotary hearth furnace.

(3) In the rotary hearth furnace of (2),
A rotary hearth furnace wherein the side wall of the rotary hearth furnace within a range in which the discharge device moves is movable.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Pellets or briquettes reduced in a rotary hearth furnace move to a plate-shaped discharge device while resting on a rotating hearth. The pellets or briquettes transferred to the discharge device are placed in a vertical plane in the direction of rotation of the hearth.
６０60 degrees, and 10 degrees in the horizontal direction
It is discharged to the outside of the furnace along a plate-shaped discharge device inclined at 45 degrees. Pellets or briquettes may run on top of the ejector, but the ejector is not vertical,
Since it is inclined in the direction of rotation of the hearth, it moves to the discharge port without clogging and falls from the chute to the bucket. The discharge device should not be able to discharge pellets or briquettes at an inclination angle of less than 10 degrees with respect to the direction of rotation of the hearth on the vertical plane. The above range is limited because pellets or briquettes that fall on the hearth over the upper part of the discharge device over the discharge device are generated. At an inclination angle of less than 10 degrees from the center line of the hearth with respect to the direction of rotation of the hearth on a horizontal plane, the pellets or briquettes hit the discharge device and overlap with the hearth, and cannot be discharged. Above this, discharge is possible, but it is limited to the above range because the discharge device is large and the length of the hearth occupied by the discharge device is long.

FIG. 1 shows an example of a discharge apparatus for a rotary hearth furnace according to the present invention. FIG. 2A is a diagram showing an example of the discharge part of the rotary hearth furnace viewed from the outer peripheral direction, and FIGS. 2B and 2C are plan views of the upper part of the hearth. FIG. 2B shows a pellet or briquette on the outer bucket, and FIG.
Indicates a state of discharging to the inner bucket.

As shown in FIG. 1 (b), the pellets or briquettes charged and reduced on the hearth 1 move along the discharge device 2 and are discharged from the discharge port 6a to the outside of the furnace.
It falls on the bucket 5 through the chute 4a. When the bucket 5 becomes full, the discharge device 2 rotates and reaches the state shown in FIG.

The rotation of the discharging device 2 can be performed by a rotating device 8 installed above the ceiling, for example, as shown in FIG. FIG. 2A is a view of the discharge device 8 as viewed from a side, and FIG. 2B is a view of the hearth portion as viewed from a plane. Discharge device 2
Is supported by a driving device 8 installed above the ceiling 10 through a driving shaft 9 provided above the position where the hearth 1 contacts. Since the drive shaft 9 has a high-temperature atmosphere in the furnace, it is preferable to use a water-cooled structure and line the exterior with a refractory from the viewpoint of improving durability. The drive shaft 9 can be attached to an upper portion of the discharge device 2 at a position in contact with the hearth or to an upper portion other than a position at which the discharge device 2 contacts the hearth. However, if it is out of the position in contact with the hearth, the moving range of the discharging device is widened, which is not preferable because the area of the discharging portion becomes large. An electric motor with a speed reducer can be used for the rotating device 8, and the rotating device 8 is fixed by a structure at the ceiling of the rotary hearth furnace.

The discharge device 2 collides with the side wall 7 of the rotary hearth during rotation.
Cannot be installed. The moving walls 3a, 3b, 3c, and 3d are provided to prevent the side wall 7 around the discharge device 2 from becoming an opening when the discharge device 2 moves. The rotary hearth furnace
Generally, the operation is performed at a negative pressure so that the CO gas generated in the furnace is not discharged outside the furnace. However, if a large opening exists in the discharge device 2, the amount of air entering the furnace increases. Because it is not preferable, as shown in FIG.
The moving walls 3a, 3b, 3c, and 3d are installed so as to move along the outer periphery of the side wall 7 to prevent the discharge device 2 from colliding with the side wall 7 and preventing air from entering through the opening.

FIG. 3A shows a plan view, and FIG.
3A shows a cross section. Moving walls 3a, 3b, 3c, 3d
Are air cylinders 11a, 11b, 11c, 11d
, The length corresponding to the movement length of the discharge device 2 can be moved, the lower part can be easily moved by attaching a car, and the upper part can be moved by attaching a guide to the ceiling. Next, the moving state of the moving walls 3a, 3b, 3c and 3d is shown in FIG. 4 together with the moving state on the outer peripheral side. FIG. 4A is a state in which the paper is discharged on the inner peripheral side, and the plan view corresponds to FIG. 1C. FIG. The state is shown, and the plan view corresponds to FIG. Since the moving walls 3a, 3b, 3c, and 3d move in accordance with the movement of the discharge device 2, an increase in intruding air can be prevented.

The discharge device 2 has a structure in which a steel pipe is machined to form a planar structure, and a refractory is lined outside the steel pipe. It is preferable because it can be improved. In addition, it is preferable to use a wear-resistant castable or to attach a ceramic to a portion of the discharge device 2 that directly contacts the pellet or the briquette in order to improve durability. Moving wall 3
A refractory is also attached to a, 3b, 3c, and 3d for heat insulation.

Although an example in which pellets or briquettes are discharged to the bucket 5 has been described, when the pellets or briquettes are cooled by a cooler, only one discharge port is required. In this case, the discharge device 2 is prevented from rotating, and the moving wall 3
a, 3b, 3c, 3d, air cylinders 11a, 11
b, 11c, and 11d are unnecessary, and the cutout of the discharge portion of the side wall 7 may be eliminated.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention in a reduced iron production facility for a rotary hearth furnace will be described.

The reduced pellets having a particle size of 7 to 10 mm and a temperature of about 1100 ° C. were discharged out of the 3T / H furnace. The discharge device was installed in a furnace with a furnace width of 2 m, and was installed obliquely at a vertical angle of 45 degrees from the hearth shown in FIG.
The discharge angle shown in B of FIG. The discharge device was made by processing a 32A steel pipe, insulated with casters, and cooled by passing cooling water through the steel pipe. In order to prevent abrasion of a portion of the discharge device that comes into contact with the pellets, a ceramic plate made of alumina was attached to a lower portion of 30 mm.

Observation of the discharge state revealed that although two or three layers of pellets overlapped the upper part of the discharge device, the pellets could be discharged without stagnation. In the present embodiment, it is assumed that the use of the ceramic plate at the lower part of the discharge device has improved the slip.

As a comparative example, the discharge device was set vertically from the hearth,
That is, when the angle A in FIG. 1A is set at 0 degree,
Pellets that could not be discharged due to accumulation of pellets at the lower part of the discharge device overlapped in front of the discharge device.

[0021]

According to the present invention, it is possible to discharge pellets or briquettes from a rotary hearth furnace without using a screw conveyor, so that it is not necessary to replace the screw conveyor, and to protect the screw conveyor. Uninterruptible power supply is not required. Furthermore, by having two outlets, a rotating device for the discharge chute becomes unnecessary, and the height of the rotary hearth furnace can be reduced, so that the foundation of the rotary hearth can be lowered and the equipment cost can be reduced, or the bucket can be reduced. This eliminates the need for a rotating device.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a rotary hearth furnace of the present invention.

FIG. 2 is a view showing an example of a rotating device of the discharge device of the rotary hearth furnace of the present invention.

FIG. 3 is a diagram showing an example of a moving wall of the rotary hearth furnace of the present invention.

FIG. 4 is a view showing a moving state of a moving wall of the rotary hearth furnace of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hearth 2 Discharge device 3a Moving wall 3b Moving wall 3c Moving wall 3d Moving wall 4a Chute 4b Chute 5 Bucket 6a Discharge port 6b Discharge port 7 Side wall 8 Rotating device 9 Drive shaft 10 Ceiling 11a Air cylinder 11b Air cylinder 11c Air cylinder 11d Air cylinder

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F27D 3/06 F27D 3/06 B (72) Inventor Shigeki Takahashi 20-1 Shintomi, Futtsu Nippon Steel Corporation (72) Inventor: Toshitaka Nakayama 46-59, Nakahara, Tobata-ku, Kitakyushu Nippon Steel Corporation (72) Inventor, Takeshi Iwanaga 46-59, Nakahara, Tohara-ku, Kitakyushu Nippon Steel F term in Plant Design Co., Ltd. (reference) 4K001 AA10 BA02 CA23 GA12 GB02 4K012 DD02 DD10 DE02 DE08 4K045 AA05 BA02 RA05 RA09 RC19 4K055 AA05 AA06 BA05 EA00

Claims (3)

[Claims] 1. A discharge device for pellets or briquettes of a rotary hearth furnace is formed in a plate shape, and the discharge device is inclined 10 to 60 degrees in the direction of rotation of the hearth in the vertical direction, and the center line of the hearth in the horizontal direction. A rotary hearth furnace characterized by being installed at an angle of 10 to 45 degrees with respect to the rotation direction of the hearth. 2. The rotary hearth furnace according to claim 1, wherein the discharge device is a rotary type, and discharge ports are provided at two locations on an inner peripheral side and an outer peripheral side of the rotary hearth furnace. 3. The rotary hearth furnace according to claim 2, wherein a side wall of the rotary hearth furnace in a range in which the discharge device moves is movable.