JP2543366Y2 - Vertical induction heating furnace - Google Patents

Description

[Detailed description of the invention]

[0001]

[Industrial application] This invention is a vertical induction heating furnace,
In particular, it relates to a furnace wall of a vertical induction heating furnace and a metal pipe support for supporting the furnace wall.

[0002]

2. Description of the Related Art Among induction heating furnaces, there is a vertical induction heating furnace having a furnace chamber whose furnace chamber is opened downward and which can be raised and lowered. In a vertical induction heating furnace, for example, the hearth supports the side surface of the material from below so that the plate surface of the plate-like material is in a vertical posture, and the hearth rises to charge the material into the furnace. The material is heated in a posture where the plate surface is vertical. Such a vertical induction heating furnace is used, for example, to heat a grain-oriented electrical steel slab to a high temperature of 1200 ° C. or more in a non-oxidizing atmosphere. By setting the inside of the furnace to a non-oxidizing atmosphere, generation of a molten scale is prevented.

When heating in a non-oxidizing atmosphere as described above, an inert gas is blown into a furnace.
Japanese Patent Application Laid-Open No. 1-136928 discloses a technique in which an inert gas is introduced into a hearth, the inert gas is preheated, and then blown into the furnace.

In general, a furnace wall is composed of a heat-resistant board, a fire-resistant brick and a heat-resistant fiber sequentially from the outside.
The refractory brick needs to be supported to prevent it from falling down, and a steel pipe or a ceramic rod through which cooling water is passed is used as a supporting member. Japanese Utility Model Laid-Open No. 61-98850 proposes a furnace wall made of a ceramic fiber refractory material.

[0005]

In the above method for introducing an inert gas into the hearth, it is expected that the preheating of the inert gas will prevent a decrease in the atmosphere temperature in the furnace and improve the heating efficiency. However, it is impossible to actively expel oxygen remaining in the furnace wall outside the furnace.

On the other hand, in the steel pipe support through which the cooling water passes, the cooling water is discharged to the outside of the furnace together with the heat from the furnace body, so that the furnace wall temperature decreases and the heating efficiency decreases. In addition, even if a ceramic rod is used, it is not possible to reduce the atmosphere temperature in the furnace due to the inert gas or to expel oxygen remaining in the furnace wall in a short time by directly blowing the inert gas into the furnace. It is.

Further, a furnace wall made of a ceramic fiber-based refractory material requires a furnace shell or a supporting column for holding the refractory material. These furnace shells or support columns need to be cooled in order to maintain the heat-resistant strength, resulting in lower heating efficiency.

This invention is intended to improve the heating efficiency and to provide a vertical induction heating furnace which can expel oxygen from the furnace in a short time.

[0009]

The vertical induction heating furnace according to the present invention is an induction heating furnace in which a furnace wall is supported by a plurality of metal pipe columns. It is provided along the support column longitudinal direction. At least the furnace wall portion between the tip or hole of the nozzle and the inner peripheral surface of the furnace wall is made of a breathable refractory material, and the inert gas supply device installed outside the furnace is connected to the metal pipe support. ing.

The number of inert gas blowing nozzles or holes is as follows:
The pitch is determined by the length of the metal pipe support and the pitch of the inert gas blowing nozzle or hole.
It is about 400 mm. A stainless steel pipe or another alloy pipe is used as the metal pipe used for the support. As a material constituting the furnace wall having air permeability, a ceramic fiber-based refractory material (chao wool, Unifelt; both are trademarks) and a spongy refractory material are used. As an inert gas,
Argon gas, nitrogen gas, or the like is used. Further, the inert gas supply device includes a container filled with an inert gas under pressure, a supply pressure adjusting device, and the like.

[0011]

When the inert gas supplied to the metal pipe support flows through the metal pipe support, it cools the metal pipe support heated by the furnace wall, and the inert gas itself is heated. The metal pipe support maintains heat resistance by cooling the inert gas. The inert gas discharged from the inert gas blowing nozzle or the hole is further heated while flowing through the furnace wall into the furnace, and is blown into the furnace. Since the inert gas is blown into the furnace at a temperature substantially equal to the furnace atmosphere temperature, a decrease in the furnace atmosphere temperature due to the inert gas injection is prevented. At this time, oxygen remaining in the furnace wall also flows into the furnace while being mixed with the inert gas. Then, the inert gas blown out into the furnace flows out of the furnace together with oxygen through a discharge port provided at the furnace top.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A vertical induction heating furnace for heating a directional magnetic steel slab will be described as an embodiment of the present invention. FIG. 4 schematically shows a vertical induction heating furnace for heating a slab. As shown in the drawing, a furnace body 1 of a vertical induction heating furnace 11
2 is open downward, and a heating coil 19 is attached to the outer periphery of the furnace wall 13. The vertical induction heating furnace 11 includes a slab turning device 26 that turns the upper and lower surfaces of the slab 1 from a horizontal position to a vertical position by 90 degrees, a hearth 31 that supports the slab 1 in the furnace in a vertical position, and a hearth 31.
Is provided with an electric winch 33 that moves up and down. The slab turning device 26 includes a claw 27 on which the slab 1 is placed, an arm (not shown) connected to the claw 27, and a claw 2 via the arm.
7 is made up of a hydraulic cylinder 28 which turns 90 degrees.
Further, the vertical induction heating furnace 11 includes a support shaft 35 for supporting the slab 1 by pressing it from above. Support shaft 35
Is raised and lowered by the air cylinder 36. Further, a roller table 37 is provided along the slab transport line L.

FIG. 1 shows a vertical section of a vertical induction heating furnace 11.
FIG. 2 shows respective cross sections. As shown in these drawings, the furnace wall 13 is constructed of ceramic fiber walls 41. A column 42 is inserted into the furnace wall 13. In this embodiment, the furnace length is 11 m, the furnace height is 3 m, and the furnace width is 370 mm. The support 21 is a stainless steel tube having a nominal diameter of 1 inch. The pitch between the columns is 500 to 600 mm, and the number of columns is 20. The furnace bottom is kept airtight by a sand seal 17.

Each pillar 42 is provided with three argon gas blowing nozzles 43 at the same height. A set of three argon gas blowing nozzles 43 is arranged at a pitch of 300 mm along the longitudinal direction of the column. The nozzle length is 30 mm and the nozzle diameter is 8 mm.

An argon gas cylinder 45 is connected to both ends of the support column 42 via pipes 46, respectively. Piping 4
A flow control valve 46 is attached to 6. It is necessary to prevent the argon gas blown from the ceramic fiber wall 41 from directly colliding with the surface of the slab 1 to generate convection heat from the slab surface. For this purpose, the argon gas is blown out from the ceramic wall 41 at a low speed,
The flow rate is adjusted by the flow rate adjusting valve 46. In this embodiment, the source pressure of the argon gas is 2 kgf / cm ² .

The argon gas supplied to the column 42 cools the column 42 heated by the furnace wall 13 when flowing through the column 42, and the inert gas itself is heated. Prop 42
Is cooled by argon gas to maintain heat resistance.
The argon gas that has exited the argon gas blowing nozzle 43 is
The heat is further heated while reaching the furnace interior 14 through the ceramic fiber wall 41 and blown out into the furnace interior 14. Since the argon gas is blown into the furnace 14 at a temperature substantially equal to the furnace atmosphere temperature, a decrease in the furnace atmosphere temperature due to the argon gas injection is prevented. At this time, the ceramic fiber wall 4
The oxygen remaining in 1 is also pushed out by the argon gas and flows out into the furnace 14. Further, the argon gas blown out into the furnace 14 flows out of the furnace through a discharge port 15 provided at the furnace top together with the oxygen in the furnace 14.

Here, an example in which the electromagnetic steel slab manufactured by the continuous casting method is heated by the vertical induction heating furnace configured as described above will be described. The slab was preheated in a gas fired heating furnace (not shown) at a relatively low rate of temperature increase to 1150 ° C. The dimensions of the slab are length 1100
0 mm, width 1000 mm, thickness 200 mm. The slab was then rapidly heated to 1350 ° C. The supply amount of the argon gas was 1000 to 1200 Nm ³ / hr. The argon gas was heated from room temperature to 400-500 ° C. before being supplied to the columns and blowing into the furnace. Table 1 shows the results of the heating time and the time required for the oxygen concentration in the furnace to reach 1000 ppm.

[0018]

[Table 1]

As is clear from Table 1, the heating time is reduced by 15% compared to the conventional method, and the time to reach 1000 ppm is 7%.
It has been reduced by 0%.

FIG. 3 shows another embodiment of the present invention.

The furnace wall 13 is sequentially heat-resistant board wall 5 from the outside.
1. Refractory brick wall 52 and ceramic fiber wall 53
It consists of. The heat-resistant board wall 51 and the fire-resistant brick wall 52 strengthen the furnace wall 13. The stainless steel pipe support 55 is provided in the fire brick wall 52. The argon gas blowing nozzle 56 opens toward the ceramic fiber wall 53 at a position where the refractory brick wall 52 and the ceramic fiber wall 53 are in contact with each other.

In the above two embodiments, each of the argon gas blowing nozzles 43 and 56 also functions as a furnace wall support reinforcement.

[0023]

According to the vertical induction heating furnace of the present invention, the inert gas supplied to the metal pipe support flows through the metal pipe support and is heated before flowing into the furnace through the furnace wall. Therefore, a decrease in the furnace atmosphere temperature due to the injection of the inert gas is prevented. At this time, the oxygen remaining in the furnace wall also flows out mixed with the inert gas. As a result, the heating efficiency is improved, and oxygen can be expelled from the furnace in a short time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a part of a vertical induction heating furnace according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a part of the vertical induction heating furnace shown in FIG.

FIG. 3 is a cross-sectional view showing a part of a vertical induction heating furnace according to another embodiment of the present invention.

FIG. 4 is a perspective view schematically showing the outline of a vertical induction heating furnace to which the present invention is applied.

[Explanation of symbols]

Reference Signs List 1 slab (heating material) 42 support 12 furnace body 43 argon gas blowing nozzle 13 furnace wall 45 argon gas cylinder 14 inside furnace 51 fireproof board wall 15 discharge port 52 fireproof brick wall 19 heating coil 53 ceramic fiber wall 31 gantry 55 support 41 ceramic fiber Wall 56 Argon gas blowing nozzle

Claims (1)

(57) [Scope of request for utility model registration] 1. An induction heating furnace in which a furnace wall is supported by a plurality of metal pipe supports, wherein a plurality of inert gas blowing nozzles or holes are provided in the metal pipe support along a longitudinal direction of the support. The furnace wall portion between the tip or hole of the furnace wall and the inner peripheral surface of the furnace wall is made of a breathable refractory material, and an inert gas supply device installed outside the furnace is connected to the metal pipe support. A vertical induction heating furnace.