JPH0543948A - How to protect the roll inside the furnace directly above the direct furnace - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to protect the in-furnace rolls installed in the roll chamber directly above the direct furnace of the vertical continuous annealing furnace from the high temperature exhaust gas of the direct furnace invading the roll chamber. .. [Structure] N ₂ gas is blown from the narrowed portions 3a and 3b provided between the direct furnace 7 and the roll chamber 6 immediately above, and the N ₂ gas is mixed with the exhaust gas of the direct furnace to try to enter the roll chamber 6 and the exhaust gas is discharged. Allow it to cool. [Effect] Since the direct-fired furnace exhaust gas is cooled by the N ₂ gas while entering the roll chamber 6, the in-furnace roll 5 can always be used at the heat resistant temperature or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for protecting an in-furnace roll provided directly above a direct furnace of a vertical continuous annealing furnace.

[0002]

2. Description of the Related Art The temperature directly above a direct-fired furnace in a vertical continuous annealing furnace becomes extremely high, and the furnace rolls used for folding the steel strip between the direct-fired furnace and the preheating furnace immediately before the furnace are affected by the influence. In order to escape, a roll chamber was separately provided between the two furnaces and installed inside the roll chamber.

FIG. 2 shows a situation in which a roll chamber 6 is provided and an in-furnace roll 5 installed therein is installed. As shown in the figure, narrowing portions 4a and 4b are provided between the direct furnace 7 and the in-core roll 5 provided directly above the in-furnace roll 5 and the pre-heating furnace (not shown). Similarly, the throttle portions 4c and 4d are provided to divide the space in which the in-furnace roll 5 is installed into a roll chamber 6.

In the structure provided with the roll chamber 6 as described above,
The high temperature exhaust gas which tries to enter the roll chamber 6 from the direct furnace 7 is blocked by the throttle portions 4a and 4b. Therefore, this exhaust gas passes through the flues 8a, 8b in the front, passes through the preheating furnace and the exhaust heat recovery device (not shown), and is discharged outdoors.

[0005]

However, if the gap between the narrowed portions 4a and 4b is set too small, the refractory material forming the narrowed portions 4a and 4b comes into contact with the metal strip X, and the surface of the metal strip X is contacted. Defects will occur.

On the contrary, if the gap between the narrowed portions 4a and 4b is made large in order to avoid the occurrence of the flaw, the high temperature exhaust gas enters the roll chamber 6 to raise the room temperature and raise the furnace roll 5
Will be damaged.

As one measure for solving such a problem, in Japanese Examined Patent Publication No. 1-21204, a metal strip folding portion provided with a roll in a furnace is made independent as an intermediate chamber,
We have proposed a structure that blocks the gas flow, but since the height of the furnace for installing such an intermediate chamber in the upper part of the direct furnace becomes high and the structure becomes complicated, a more simplified furnace roll protection measure is required. Development was desired.

The present invention was devised in view of the above problems of the prior art, and it is an object of the present invention to provide a method for effectively protecting a furnace roll installed directly above a direct furnace from high temperature exhaust gas from the direct furnace. Is.

[0009]

Therefore, as a measure for protecting the rolls in the furnace of the present invention, the temperature of the exhaust gas entering the roll chamber can be lowered while allowing the exhaust gas of the direct furnace from entering the roll chamber to some extent. The specific configuration is as follows: As a specific configuration, an inert gas or a reducing gas is blown into the roll chamber from a throttle provided between the direct furnace and the roll chamber above it. The basic feature is that the gas is cooled by being mixed with the exhaust gas from the direct furnace.

By cooling the direct-fired furnace exhaust gas entering the roll chamber in this manner, there is no risk of damaging the in-furnace roll.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic equipment diagram showing the construction of equipment for carrying out the method of the present invention. The equipment shown in the figure shows the structure of the direct furnace 7 of the vertical continuous annealing equipment and the part of the roll chamber 6 immediately above it, and since the basic structure is the same as the conventional structure described above, the same structure is the same. The numbers are shown.

In this embodiment, on the furnace walls of the narrowed portions 3a and 3b provided between the direct furnace 7 and the roll chamber 6 immediately above it,
The opening portions 1a to 1d communicating with the gas headers 2a to 2d are provided,
N ₂ gas is blown into the furnace from the external N ₂ gas supply source (not shown) through the gas headers 2a to 2d through the openings 1a to 1d.

With the above construction, the high temperature exhaust gas of the direct furnace, which is about to enter the roll chamber 6, mixes with the blown room temperature N ₂ gas, is cooled, and enters the roll chamber 6.

In the actual blowing of N ₂ gas, the temperature inside the roll chamber 6 is measured, and based on the detected temperature, more specifically, the temperature therein is below the heat resistant temperature of the in-furnace roll 5. The N ₂ gas injection amount is controlled so that

In the structure of the present embodiment, if the gas injection speed is made higher than that adopted in the above control, the gas sealing effect becomes larger than the gas cooling effect by mixing, and this also causes the in-furnace roll due to the high temperature exhaust gas. The damage of 5 disappears.

As a result of the above operation, the roll chamber
The temperature of the gas entering 6 decreased, and the in-furnace roll 5 could always be used at a temperature lower than the heat-resistant temperature. As a result, the roll life, which had been about three months until now, is extended to one year or more. Further, since the processing is performed by utilizing the gas cooling effect of the normal mixing, the consumption amount of N ₂ gas is very small, and the flapping of the plate does not occur.

In addition, N ₂ gas is used as the gas used for blowing, but this is because the steel strip X is already 250 in the preheating furnace.
It is heated to about 0 ° C and is in a state of being easily oxidized, and is selected for the purpose of preventing this. Therefore, any non-oxidizing gas may be used, and an inert gas such as Ar gas or a reducing gas such as H ₂ gas may be used.

[0019]

According to the method for protecting the inner roll of the present invention described in detail above, it is possible to prevent damage to the inner roll due to intrusion of high temperature direct-fired furnace exhaust gas by blowing a small amount of gas. This will help extend the roll life.

[Brief description of drawings]

FIG. 1 is a schematic view of the equipment showing the construction of equipment for carrying out the method of the present invention.

FIG. 2 is a cross-sectional view showing how a roll in a furnace is installed in a roll chamber.

[Explanation of symbols]

 1a to 1d Opening 2a to 2d Gas header 3a, 3b Throttling 4a to 4d Throttling 5 Inner roll 6 Roll chamber 7 Direct furnace 8a, 8b Flue X Steel strip

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichi Fukushima 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd.

Claims (1)

[Claims] 1. A direct-fired furnace exhaust gas which blows an inert gas or a reducing gas from a narrowing portion provided between a direct-fired furnace of a vertical continuous annealing furnace and a roll chamber above the direct-fired furnace and tries to enter the roll chamber. A method for protecting a roll in a furnace directly above a direct-fired furnace, which is characterized by mixing and cooling the gas.