JP2001324274A - Rotary hearth heating furnace for steel billets - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary hearth heating furnace comprising the means of a structure of which castable refractory at a positioning part is hard to be destroyed by the thermal expansion of the castable refractory of a hearth center main body, and having no danger of small fallen off pieces biting into the gap between furnace walls when the refractory at the positioning part is deteriorated. SOLUTION: The rotary hearth heating furnace comprises a hearth center main body 5 comprising a rotatable furnace body frame 2, heat insulating bricks 3 laid on the furnace body frame 2 and the castable refractory 4 arranged on the heat insulating bricks 3, and the positioning part 7 of the inner and outer circumference of the hearth comprising refractory 6 on the furnace body frame 2 of the inner and outer circumference of the hearth center main body 5. A step part 8 is formed by elevating the inner and outer circumference of the heat insulating bricks 3 of the hearth center main body 5 with the same heat insulating bricks 3, expansion joints 9 are arranged between the heat insulating bricks 3 forming the step part 8 and the castable refractory 4 inside the heat insulating bricks 3, the positioning part 7 of the hearth inner and outer circumference on the outer side of the inner and outer circumference of the heat insulating bricks 3 of the hearth center main body 5 is arranged with a castable refractory 10, L fittings 11 fixed to the hearth body frame 2 are arranged to the outer circumference of the castable refractory 10, and positioning refractory 12 formed by laminating the inorganic fiber heat insulating material on the castable refractory 10 is fixed to the capable of refractory 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hearth structure using an irregular refractory in a steel heating furnace, and more particularly, to a rotary and horizontal moving type hearth moving type using an irregular refractory as a hearth material. It relates to a heating furnace of the type.

[0002]

2. Description of the Related Art A rotary hearth heating furnace of a movable hearth type for heating steel billets or the like is provided with a heat insulating brick 3 as a heat insulating material on a furnace body frame 2 and an irregular refractory 4 thereon. 1
The section has a space of 3m ² , 0.6m ³
mm. As for the positioning of the inner and outer peripheries of the insulating brick 3 and the irregular refractory 4 thereon,
A Y-stud 17 is attached from the furnace body frame 2, an irregular-shaped refractory 10 is provided around the Y-stud 17, and a heat-resistant L-shaped metal member 11 is arranged on the outermost periphery for reinforcement. The inner and outer peripheral frames are composed of ten. Thereby, the furnace wall 1
It is possible to narrow the gap between the furnace wall 14 and the furnace wall 5 having the heat insulating effect.

However, such a conventional rotary heating furnace has the following problems. When the billet placed on the hearth is heated, a scale made of an oxide is generated on the surface of the billet, and the scale falls on the hearth. The fallen scale enters the cracks and joints generated by the expansion allowance 9 and the deterioration of the amorphous refractory 4 due to the change in the furnace temperature when the furnace is closed. Since the place where the irregular refractory 4 on the hearth goes is lost, the irregular refractory 10 for positioning the inner and outer circumferences is destroyed. The broken refractory 10 for positioning is located between the furnace walls 1
4 and the partial damage phenomenon will cause damage to the entire furnace.

[0004] A similar situation occurs when the irregular-shaped refractory 10 for positioning the inner and outer circumferences is partially dropped due to thermal deterioration.

[0005] As shown in FIG. 4, since the amorphous refractory 10 is held only halfway upward from the lower furnace body frame 2 side by the heat-resistant L-shaped hardware 11,
The upper part of the mold 11 is broken. The reason for the crack is the gap between the force for pushing the refractory 10 due to the expansion of the refractory 4 and the holding force of the L-shaped metal 11. If the L-shaped metal member 11 is directly exposed to the furnace atmosphere, even if it is heat resistant, it glows red and the oxidation is accelerated, the life is shortened, and the frequency of replacement is increased. Since the structure is difficult to replace, the height can only be secured halfway.

Therefore, in the prior art, as shown in FIG. 2, the upper part of the irregular refractory 10 and the irregular refractory 4
Is provided with an expansion allowance 9 of, for example, 50 mm made of an inorganic fiber-based heat insulating material to absorb the thermal expansion of the amorphous refractory 4 to prevent cracks and gaps. However, even in this case, there is a problem that the irregular-shaped refractory 4 is displaced because it can move freely because it is only placed on the insulating brick 3. When the irregular refractory 4 is displaced and the expansion allowance 9 of 50 mm is not crushed, the irregular refractory 10 indicated by a hatch is pushed and damaged.

As described above, in the conventional rotary hearth heating furnace for heating billets and the like, when the refractory of the furnace deteriorates and scales are deposited on joints, the furnace is installed for positioning the hearth by expansion and contraction. There is a problem that the irregular-shaped refractory 10 of the inner and outer peripheral frames may be destroyed, which causes a serious facility stoppage.

[0008]

An object to be solved by the present invention is to solve the above-mentioned problems of the conventional rotary heating furnace, and the irregular-shaped refractory in the center body of the hearth thermally expands. Even if the refractory of the positioning part is made of a means that is hard to break even if the refractory of the positioning part is degraded, the rotary hearth type that does not fall out even if the refractory of the positioning part deteriorates and the small pieces do not bite between the furnace walls It is to provide a heating furnace.

[0009]

According to the first aspect of the present invention, a rotatable furnace frame 2 and a heat insulating brick 3 stretched on the furnace frame 2 are provided. A hearth center main body 5 composed of an irregular refractory 4 provided on the insulating brick 3 and a positioning part for the inner and outer periphery of the hearth composed of the refractory 6 on the furnace body frame 2 on the inner and outer periphery of the hearth central body 5. 7, the inner and outer peripheral portions of the heat insulating bricks 3 of the hearth center main body 5 are raised to the height of 65 mm or more by the same heat insulating bricks 3 to form stepped portions 8.
Is provided with an expansion allowance 9 of 25 mm or more, preferably 30 mm, between the insulated brick 3 and the irregular refractory 4 inside the brick. The positioning part 7 on the inner and outer periphery of the hearth, which is the inner and outer periphery of the heat insulating brick 3 of the hearth center main body 5, is positioned by the irregular refractory 10 installed on the inside and outside of the heat insulating brick 3, and is bolted to the furnace body frame 2. L-shaped hardware 11 (SCH-1
1) is disposed on the outer periphery of the irregular-shaped refractory 10 and the insulating brick 3
The upper portion of the irregular refractory 4 above the stepped portion is positioned above the lower surface of the irregular refractory 4 in place of the conventional irregular refractory B on the inner and outer circumferences. A rotary hearth heating furnace fixed to a fixed refractory 10. Therefore, even if the refractory positioning material 12 is deteriorated and damaged, the refractory material is made of the inorganic fiber-based heat insulating material, so that the refractory material 12 is hardly broken into small pieces and is not easily caught between the furnace walls.

According to a second aspect of the present invention, there is provided a rotary hearth heating furnace according to the first aspect, wherein the expansion allowance 9 is formed of an inorganic fiber heat insulating material 16.

According to the third aspect of the present invention, the upper surface of the irregular-shaped refractory is lower than the lower surface of the irregular-shaped refractory on the stepped portion of the heat-insulating brick, and the positioning refractory is positioned on the irregular-shaped refractory.
2. The stud 13 is fixed at 0.
Or a rotary hearth heating furnace according to the second means.

The operation of the present invention will be described below. In the means of claim 1, the inner and outer peripheral portions of the hearth made of the amorphous refractory 10 are such that the gap with the furnace wall is made as narrow as possible.
Energy loss is reduced because heat dissipation is reduced. Therefore, the space between the furnace walls should be as narrow as possible. However, narrowing the space between the furnace walls causes small pieces missing from the above-mentioned irregular-shaped refractory 10 to bite between the furnace walls. Therefore, the cause of the generation of the small pieces is eliminated.

By using the positioning refractory 12 made of an inorganic fiber-based heat insulating material in order to narrow the gap with the furnace wall, the gap with the furnace wall can be set narrow. When the gap is set to be small, the possibility of contact with the furnace wall surface increases, but the contacting member is only abraded due to the inorganic fiber system and does not break the furnace wall surface. In addition, degradation due to heat effects and contact,
Even when abrasion occurs, repair can be easily performed by partial replenishment with an adhesive, so that maintenance can be easily performed on site, so that heat loss can be reduced. Furthermore, even if the amorphous refractory 4 expands, the expansion is absorbed by the positioning refractory 12 made of an inorganic fiber-based heat insulating material, so that the amorphous refractory 4 does not crack.

The refractory 4 only rests on the insulating brick 3. For this reason, heating / cooling of refractory
Each time is expanded or contracted, the insulating brick 3 does not necessarily expand or contract on a concentric circle, but is displaced. This is a cause of cracking of the irregular-shaped refractory 10 and generation of a gap between the irregular-shaped refractory 4 and the irregular-shaped refractory 10. That is, the conventional refractory 1 fixed with the L-shaped metal member and the Y stud 17
At 0, the irregular refractory 4 was prevented from slipping, so the irregular refractory 4 did not slip. However, a force is applied to the irregular refractory 10 by that much, and the irregular refractory 10
Cracks and gaps were formed between the irregular refractory 4 and the irregular refractory 10. Therefore, as described above, in the prior art, an expansion allowance 9 made of an inorganic fiber-based heat insulating material is provided between the irregular-shaped refractory 10 and the irregular-shaped refractory 4 on the upper layer side to prevent cracks and gaps. According to the invention of claim 1 of the present application, it is necessary to further measure the displacement of the refractory 4, that is, to position the refractory 4. Is equal to or lower than the upper end of the L-shaped metal member 11. As a result, the lower portion of the refractory 4 is embedded in the step portion, and the inner and outer step portions 8 are formed.
I couldn't move as a whole because I could only move inside. Furthermore, the upper surfaces of the insulating brick 3 and the irregular-shaped refractory 10 are not exposed, and foreign matter does not bite into the gap. Moreover, since the inner and outer peripheries of the hearth are also covered with the L-shaped hardware 11, even if broken, small pieces do not fall and there is no bite between the furnace walls.

According to the second aspect of the present invention, when the expansion allowance 9 is provided between the irregular refractory 4 and the insulating brick 3 and below the upper irregular refractory for compensation, foreign matter from the outside can be obtained. Since it cannot be mixed, the expansion allowance can be maintained. Especially expansion allowance 9
Is formed from the inorganic fiber-based heat insulating material 16, the inorganic fiber-based heat insulating material 16 can efficiently absorb the stress caused by the expansion of the surroundings, so that damage can be prevented and cracking from this portion does not occur.

When the irregular refractory 4 has a width of 2,825 mm, the inorganic fiber-based heat insulating material 16 must be at least 25 mm, preferably 30 mm, in order to compensate for the thermal expansion allowance by 25 mm.
Just insert it.

By absorbing the expansion of the amorphous refractory 4 on the hearth with the inorganic fiber-based heat insulating material 16, it is possible to prevent the breakage of the amorphous refractory 10 in the prior art caused by the expansion and deterioration of the refractory.

According to the third aspect of the present invention, the refractory having an irregular shape is provided.
Is lower than the lower surface of the irregular refractory 4 on the step 8 of the insulating brick 3, so that the irregular refractory 10 is in contact with the insulating brick 3 but is in contact with the irregular refractory 4. Since it is not present, it is not pushed by the thermal expansion of the amorphous refractory 4 and therefore hardly cracks. The positioning refractory 12 made of an inorganic fiber-based heat insulating material on the upper portion is fixed to the hard-to-break irregular-shaped refractory 10 with the studs 13, so that the position of the positioning refractory 12 is stable.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. As shown in the plan view of FIG. 3, the rotary hearth heating furnace has an outer diameter of, for example, about 20 m15 cm, and rotates between the outer peripheral furnace wall 15 and the inner peripheral furnace wall 15. An annular rotary hearth 1 is formed. The width of the rotary hearth 1 is 3m5
0 cm. And the diameter of the center of the width of the rotary hearth is 17m
50 cm. The billet to be heated is charged from the charging port 18, and the heated billet is taken out from the discharging port 19 while rotating in the furnace. Cross sections of the furnace walls 15, 15 and the rotary hearth 1 shown by arrows AA in FIG. 3 are shown in FIG. 4 as a conventional apparatus. The hearth 1 has a furnace body frame 2 made of a rotatable rolled steel material, and an insulating brick 3 stretched on the furnace body frame 2 through heat insulating concrete. Insulation brick 3
A high-strength castable irregular refractory 4 is formed on the upper part to form a hearth center main body 5. On the inner and outer peripheries of the hearth center main body 5, there are positioning portions 7 for the inner and outer peripheries of the hearth made of the refractory material 6 on the furnace body frame 2. In the embodiment of the invention according to claim 1 of the present application, FIG. 1 shows a partial cross-sectional view on the outer peripheral side instead of FIG. 4 of the above-described conventional apparatus. The inner and outer peripheral portions of the heat-insulating brick 3 of the hearth center main body 5 are made of the same heat-insulating brick 3 and are raised to a height of 65 mm or more to form a stepped portion 8, so that the cross section of the heat-insulating brick 3 is concave. . The width of this step is 40 cm or more from the inner and outer circumferences. The inside of the insulated brick 3 on the recess forming the stepped portion 8 on the inner and outer periphery of the hearth center body 5 of the rotary hearth 1 is filled with a high-strength castable amorphous refractory 4. 25 between the insulating brick 3 and the irregular refractory 4
An expansion allowance 9 of not less than mm, preferably an expansion allowance 9 of 30 mm is provided. The positioning part 7 on the inner and outer circumferences of the hearth, which is the inner and outer circumferences of the insulating bricks 3 of the hearth center main body 5, is provided with an amorphous refractory 10 made of a high-strength castable and positioned on the inner and outer circumferential sides of the insulating bricks 3. Around the irregular-shaped refractory 10, SCH-11 which is a heat-resistant cast steel bolted to the furnace body frame 2 is provided.
Is provided. On the step portion 8 of the insulating brick 3, the irregular refractory 4 is formed integrally and continuously with the irregular refractory 4 provided on the inner insulating brick 3. The positioning portion 7 on the upper side of the lower surface of the amorphous refractory 4 on the step portion 8 is formed by laminating an inorganic fiber-based heat insulating material made of ceramic fiber instead of the conventional amorphous refractory 10 on the inner and outer circumferences. Then, the refractory is positioned. Then, the positioning refractory 12 of the inorganic fiber-based heat insulating material is fixed to the positioning irregular-shaped refractory 10 below. As shown in the figure, the upper corner of the positioning refractory 12 is chamfered and inclined obliquely, and the furnace wall 15 facing that portion is also obliquely formed.

With the above construction, even if the refractory positioning material 12 is deteriorated and damaged, the refractory material is made of an inorganic fiber-based heat insulating material, so that the refractory material is hardly broken off into small pieces and does not bite into the space 14 between the furnace walls. Therefore, the space 14 between the furnace walls is 100 mm at the vertical furnace wall.
The gap can be made extremely narrow, for example, 75 mm or more in the part of the furnace wall 14 formed obliquely at an angle of 75 mm, so that the heat loss can be reduced.

According to an embodiment of the present invention, there is provided a rotary hearth heating furnace according to the above embodiment, further comprising an inorganic fiber-based heat insulating material 16 made of ceramic fiber attached to the expansion allowance 9. In this embodiment, the inorganic fiber-based heat insulating material 16 has the expansion allowance 9, so that the step portions 8 on the inner and outer circumferences are provided.
Even if the irregular refractory 4 in between moves due to thermal expansion on the insulating brick 3, the thermal expansion is absorbed by the inorganic fiber-based heat insulating material 16 and does not destroy the irregular refractory 4.

Further, in the embodiment according to the third aspect of the present invention, in the means of the first or second aspect of the present invention, the high strength part of the positioning portion 7 on the inner and outer periphery of the hearth is further provided. The upper surface of the castable irregular refractory 10 is formed lower than the lower surface of the irregular refractory 4 on the step 8 of the insulating brick 3. And this irregular refractory 10
The refractory for positioning 12 formed on the upper surface of the
This is a rotary hearth heating furnace fixed to studs 13 at 0.
In this embodiment, the irregular-shaped refractory 10 is a heat-insulating brick 3
But not in contact with the refractory 4
It is not pushed by the thermal expansion of the amorphous refractory 4.
Therefore, the positioning refractory 12 which is hard to crack and which is made of an inorganic fiber-based heat insulating material is fixed to the hard-to-break irregular refractory 10 with the studs 13, so that the positioning refractory 12 is always stably immobile. It is.

The rotary hearth heating furnace of the present invention has an atmosphere temperature of 1000 to 1200 ° C., a billet steel material size of φ50 to 200 mm, and a height of 800 to 2500 m.
m, furnace shutdown: 2 times / year complete fire extinguishing to cool to room temperature,
It is operated at other occasions with the temperature kept at about 600 ° C., and the irregular refractory 10 on the inner and outer circumferences is not damaged at all. In the conventional method, the irregular-type refractory 10 was dropped out in about three years and was partially damaged.

[0024]

As described above, according to the present invention, the shape of the insulating brick is devised, and the positioning portions on the inner and outer peripheries of the hearth are made of a refractory made of an irregular-shaped refractory and an inorganic fiber-based heat insulating material thereon. When the refractory of the central body expands, the refractory of the positioning part on the inner and outer circumferences of the hearth hardly breaks, and even if the refractory deteriorates, it is missing. Even if the inorganic fiber-based heat insulating material is worn further, repair is extremely easy, and small pieces of irregular-shaped refractory can be stably operated for a very long time without biting between furnace walls. This is a rotary hearth heating furnace that has an unprecedented superior effect.

[Brief description of the drawings]

FIG. 1 is a partial schematic diagram showing a cross section of a rotary hearth heating furnace according to an embodiment of the present invention.

FIG. 2 is a partial schematic view showing a cross section of a conventional rotary hearth heating furnace.

FIG. 3 is a plan view schematically showing a rotary hearth heating furnace.

FIG. 4 is a sectional view taken along the line AA of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary hearth 2 Furnace frame 3 Insulated brick 4 Unshaped refractory 5 Hearth center main body 6 Refractory 7 Positioning part 8 Step part 9 Expansion allowance 10 Unshaped refractory 11 L-shaped metal 12 Positioning refractory 13 Stud 14 Furnace Between walls 15 Furnace wall 16 Inorganic fiber-based heat insulating material 17 Y stud 18 Inlet 19 Outlet

Claims (3)

[Claims] 1. A hearth center main body 5 comprising a rotatable furnace body frame 2, an insulating brick 3 stretched on the furnace body frame 2, and an irregular refractory 4 provided on the insulating brick 3; In a rotary hearth heating furnace comprising a hearth inner and outer circumference positioning portion 7 made of a refractory material 6 on the furnace body frame 2 on the inner and outer circumferences of the central body 5, an inner and outer peripheral portion of the heat insulating brick 3 of the hearth central body 5 Is formed in the stepped portion 8 by the same heat insulating brick 3, and an expansion allowance 9 is provided between the heat insulating brick 3 forming the stepped portion 8 and the indefinite refractory 4 inside the stepped portion 8, and the heat insulation of the hearth center main body 5. An irregular-shaped refractory 10 is provided at a positioning portion 7 on the inner and outer periphery of the hearth outside the inner and outer periphery of the brick 3, and an L-shaped metal 11 fixed to the furnace body frame 2 is disposed on the outer periphery of the irregular-shaped refractory 10. An inorganic fiber-based heat insulating material is laminated on a fixed refractory 10 and an irregular shaped refractory 12 is formed. A rotary hearth heating furnace fixed to the fire 10. 2. The rotary hearth heating furnace according to claim 1, wherein the expansion allowance 9 is formed from an inorganic fiber heat insulating material 16. 3. The upper surface of the refractory of irregular shape 10
3. The rotary hearth type according to claim 1, wherein the refractory is positioned lower than the lower surface of the refractory on the stepped portion, and the refractory for positioning is fixed to the refractory with studs. heating furnace.