JPS58161729A - Construction of air permeable solid wall for continuous heat treatment furnace - Google Patents

Abstract

PURPOSE:To provide titled construction which is improved in heat transmission efficiency, is provided with high strength to external force and is reduced in installation cost by the constitution wherein the inside of a direct firing nonoxidative furnace is partitioned with air permeable solid walls of a split type provided with supporting frames, etc. CONSTITUTION:The inside of a vertical continuous heat treatment furnace of a direct firing nonoxidative heating type which heats a strip material forming the plural passes guided with hearth rolls 11 by means of heaters 12 is partitioned with air permeable solid walls 4 facing the material 1, and a combustion gas is flowed through the walls to heat the material 1 efficiently with the solid radiation heat. The walls 4 are made into a split type, and supporting members 2 consisting of metallic pipes having horizontal refractory materials in the furnace are provided in the furnace. Protectors 3-1 of heat resisting steel having heat insulating materials are disposed at prescribed intervals in the longitudinal direction of said members to support the walls 4. Supporting frames 6-1 and cushion materials 5 are disposed between the members 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on a direct fire non-oxidation heating type vertical continuous heat treatment furnace (
This article concerns the structure of a permeable solid wall in a NOF (hereinafter referred to as NOF, including a preheating furnace).

In general, in continuous heat treatment furnaces for I/N materials, strip materials are treated in a mildly oxidizing atmosphere of N at temperatures of 500 to 700°C.
It is heated by OF. The furnace temperature is 1200-1300
However, in conventional NOF, the temperature of the furnace wall surface is thought to be 100 to 150 degrees Celsius lower than the furnace temperature, so there is still room for improvement in heat transfer efficiency.

FIG. 1 shows the layout of a conventional NOF, in which a strip 1 is introduced into the furnace from one furnace charging port.

It is heated by the heating device 12 while forming a plurality of baths by the hearth roll 11 . Since such a conventional NOF has poor transmission efficiency, the present inventors replaced the furnace wall of FIG. 1 with the permeable solid material 4 shown in FIG.
By installing them facing each other and letting the combustion gas flow through the air-permeable solid wall 4, the temperature of the air-permeable solid wall surface and the combustion gas are almost equal, so that solid radiation from the air-permeable solid surface with high radiation activity is reduced. Due to its large size, heat transfer efficiency can be increased compared to conventional NOF.

On the other hand, in a vertical continuous heat treatment furnace for strip material, there is a risk that the string material may break.6C1 At that time, the broken string material may damage the breathable solid. However, due to its nature, the breathable solid does not have the strength to withstand external forces such as plate breakage, and the structure of installing the breathable solid in the furnace poses a problem.

In view of the above points, the present invention aims to reduce the equipment cost by shortening the length of the equipment by changing the NOF heat transfer surface configuration in direct-fired non-oxidation furnaces. For the purpose of this, a breathable solid is placed inside the NOF
The purpose of this invention is to effectively support the gas permeable solid wall, which is arranged to cover 65% or more of the gas passage area, and to obtain a gas permeable solid wall structure that has high strength against external forces such as strip breakage. A feature of the present invention is that it is composed of a split type breathable solid, a support pipe, a protector, a breathable solid support frame, etc.

Note that the breathable solid here refers to a porous material that has air permeability and a suitable pressure drop.Metallic materials include foamed metals, sintered metals, etc. 647, and refractory materials include ceramic porous bodies, porous SjC, and alumina. There are things such as pole combinations.

In general, this type of air-permeable solid is porous, so it approximately approximates packed bed heat transfer, and the equivalent diameter of the air-permeable solid is 01 to l.
If it is about I11, l O2 ~ 103kcad/m”
Since a large convective heat transfer coefficient of h °C is obtained, the surface temperature of a breathable solid becomes almost instantaneously heated (or cooled) to near the gas temperature.

An embodiment of the present invention will be described below with reference to the drawings.

In order to support the permeable solid and to propagate external forces such as plate breakage to the furnace shell metal parts, which are heated by the strength members of the furnace body, main support members such as support pipes 2 (
(hereinafter referred to as main support 2) is installed horizontally. This pie 12 has bending rigidity against its own weight due to the refractory material lined on its outer surface and sufficient strength under high temperature atmospheric conditions to withstand the external force caused by the breakage of the strip material 1, and is supported by the furnace shell hardware. , the outer surface is lined with refractory material 9. Furthermore, since the support pawl 2 needs to have a small diameter and sufficient impact strength, it is advantageous to use a metal pawl. Also, if necessary, cooling can be achieved by flowing air into the inner surface of the pipe. Note that combustion air can be used as this cooling air. or,
The support pipe 2 may have a single-vib structure as shown in FIG. 3 (-), or a pair of connected pipes as shown in FIG. 4), for example.

In order to prevent the broken strip material 1 from damaging the breathable solid material 4, a protector 3- for protecting the breathable solid material 4 is provided so that it can cope with the breakage of the strip material of any width. 1.3-2 are arranged at predetermined intervals in the length direction of the vibrator 2.

As shown in Figure 3, when the temperature of the passing combustion gas is low (lower than 1000℃), heat-resistant steel 3-1 with a refractory material on the outer surface is used as a protector.
As shown in the figure, the area where the combustion gas temperature is high (1000℃
In the case described above), a structure using refractory bricks 3-2 can be considered. The protector can be provided with a groove to support the breathable solid 4 and can also serve as a support frame.

A frame 6 for supporting the breathable solid 4 with a support pipe is provided in the middle. This frame 6 is made of metal 6-1 in the area where the temperature of the combustion gas passing through is low (below 1000℃), and is made of firebrick 6-1 in the area where the temperature of the combustion gas is high (1000℃ or more).
2 can be considered. Each frame has a groove with one side inclined so that it can be easily replaced when the air permeable solid 4 is damaged.

In order to prevent the impact load at the time of plate breakage from acting on the breathable solid 4 through the support main 2, and to prevent damage to the breathable solid due to thermal deformation difference between the frame 6 and the breathable solid 4, the breathable solid 4 and Frame 6
A cushioning material 5 is inserted between.

Furthermore, a frame 6-3, 6-4 is inserted at the connection portion between the air-permeable solids 4 to prevent mutual influence during thermal deformation. In addition, 7 is a furnace shell, and 8 is a small fireproof insulation layer.

As described above, the present invention provides a continuous heat treatment furnace in which heat-resistant supporting materials are arranged at predetermined intervals in the height direction between the strip materials, the furnace wall, and the furnace wall. A breathable solid and a protector are placed on the wall to maintain a structure that protects the breathable solid wall from external forces such as plate breakage, and a breathable solid of a predetermined thickness is stably installed. Therefore, the present invention is extremely useful in applying air-permeable solids to continuous heat treatment furnaces1, and its industrial value is extremely high.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the layout of a conventional direct-fired non-oxidizing furnace, and FIG. 2 is a sectional view showing the layout of a direct-fired non-oxidizing furnace incorporating a permeable solid wall. Figure 3 shows the case where the temperature of the combustion gas passing through is low (1000
It shows an example of the furnace structure at ℃ end #)K, where (a) is a front view, (b) is a BB sectional view of (a), and (c) is a of ←).
2) is a sectional view taken along line A-A of 0). Figure 4 shows an example of the furnace structure when the combustion gas temperature is high (1000°C or higher), where (a) is a front view, and (←) is (a).
(c) is a cross-sectional view taken along line CC, (c) is a cross-sectional view taken along line DD of (b), and (b) is a detailed view of part b of (o). ■...Strip material, 2...Support pipe,
3-1゜3-2...Protector, 4...Breathable solid, 5...Cushioning material, 6...Support frame Patent applicant agent Patent attorney Tomoyuki Yafuki (and others 1)
name] 1st! lO Figure 2 Figure 3 (B) (A) (C) C2) -
1 Figure 4

Claims (1)

[Claims] In a continuous heat treatment furnace where metal strip material forms multiple nodules via rolls, it can be fixed to or removed from the furnace wall between the strip material and the string material, or between the strip material and the furnace wall. The heat-resistant support members are arranged at predetermined intervals in the height direction, and protectors are arranged at predetermined intervals in the length direction of the heat-resistant support members, and within the frame formed by the heat-resistant support members and the protectors. A ventilated solid wall structure of a continuous heat treatment furnace characterized by having a ventilated solid wall.