JPH07102326A - Continuous annealing furnace for metal strip - Google Patents

Abstract

PURPOSE:To provide a continuous annealing furnace for metal strip, in which the desired optional temp. distribution in the furnace can be set and the recovering ratio of the heat held in the combustion exhaust gas is high. CONSTITUTION:In the continuous annealing furnace for metal strip arranging a muffle 21 in the inner part of the furnace body 11 and fitting plural burners to this furnace body 11, the inner part of the furnace body 11 is parted into plural zones 41-43 or the furnace body is constituted of plural unit furnace bodies, and at least one pair of heat storage type buners 51a-56a, 51b-56b are fitted to each zone or each unit furnace body.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a continuous annealing furnace for metal strips. When annealing a metal strip,
For example, when bright annealing a strip-shaped stainless steel plate,
A continuous annealing furnace is used. The present invention relates to improvements in such a continuous annealing furnace.

[0002]

2. Description of the Related Art Conventionally, as a continuous annealing furnace for metal strips, a furnace in which a muffle is provided inside a furnace body and a plurality of burners are attached to the furnace body is used. Such a conventional continuous annealing furnace, while continuously transporting the metal strip inside the muffle, burns a plurality of burners attached to the furnace body to indirectly inject the metal strip under a predetermined atmospheric gas composition formed inside the muffle. The annealing treatment is performed by heating. In this case, the combustion exhaust gas of the burner generally flows from the upstream side to the downstream side in the transport direction of the metal strip between the furnace body and the muffle, and is discharged into the atmosphere from the most downstream side, but to the most downstream side. It is also practiced to connect a recuperator, recover the heat of the combustion exhaust gas with the recuperator, and preheat the combustion air of the burner with the recovered heat.

However, in the conventional continuous annealing furnace as described above, the combustion exhaust gas of the burner flows from the upstream side to the downstream side of the metal strip transportation method, and the combustion exhaust gas generated on the upstream side affects the downstream side. However, since it is difficult to grasp the degree of influence, it is not possible to set a desired temperature in the furnace metal strip transport direction. Further, the conventional continuous annealing furnace as described above has a drawback that the recovery rate is low although the heat retained in the combustion exhaust gas is recovered by the recuperator.

[0004]

The problem to be solved by the present invention is that, in the conventional continuous annealing furnace for metal strips, a desired temperature distribution cannot be set in the furnace, and the combustion exhaust gas retains it. The point is that the heat recovery rate is low.

[0005]

SUMMARY OF THE INVENTION The present invention, however, provides a continuous annealing furnace for metal strips in which a furnace is equipped with a muffle and a plurality of burners is installed in the furnace body. It is divided into a plurality of zones or the furnace body is composed of a plurality of unit furnace bodies, and at least a pair of regenerative burners are installed for each zone or for each unit furnace body. It concerns a continuous annealing furnace for metal strips.

In the present invention, a muffle is equipped inside the furnace body, and the metal strip is continuously conveyed inside the muffle. When the furnace body is integrally formed, the inside of the furnace body is divided into a plurality of zones, and when the furnace body is divided and formed, the furnace body is composed of a plurality of unit furnace bodies. Has been done. In the furnace body, for each divided zone or for each divided unit furnace body,
At least a pair of regenerative burners are installed, and the combustion flame of the regenerative burners is injected between the furnace body and the muffle.

The heat storage type burner has a burner and a regenerator integrally formed. In the present invention, such two heat storage type burners are used as a pair, and each divided zone or each unit furnace body divided. At least a pair of regenerative burners are attached to the two, and two regenerative burners forming a pair are alternately switched and burned to realize highly efficient combustion. Specifically, the combustion exhaust gas when one heat storage burner is burnt is passed through the regenerator of the other heat storage burner that forms a pair with the combustion exhaust gas, and the heat held by the combustion exhaust gas is loaded into the regenerator. The stored heat is accumulated in a small piece of ceramic such as a small piece of alumina, and then the operation of using high temperature preheated air through the stored regenerator as air for burning the other regenerative burner is repeated. To do.

An air supply valve is connected to the regenerator of each heat storage type burner, and a common air supply fan for supplying combustion air to each heat storage type burner is provided upstream of each air supply valve. Are connected. An exhaust valve is connected to the regenerator of each regenerative burner, and a common exhaust fan for discharging combustion exhaust gas is connected to the downstream side of each exhaust valve. When burning one of the regenerative burners, a common air supply fan →
Air supply valve → Regenerative generator of one heat storage type burner supplies combustion air at the same time, and at the same time forms a pair with the regenerator of the other heat storage type burner → Exhaust valve → Combustion exhaust gas through shared exhaust fan path Is discharged. In this case, the furnace pressure between the furnace body and the muffle can be detected, and the opening degree of the exhaust valve, the rotation speed of the exhaust fan, etc. can be controlled so that the detected value becomes a set value.

The two regenerative burners forming a pair can be mounted at the same position relative to the transport direction of the metal strip, but their combustion flames are injected in the direction along the inner peripheral surface of the furnace body. Therefore, it is preferable to mount the metal strip at a position deviated from the transport direction. For example, both regenerative burners are installed so that their combustion flames are injected in the tangential direction of the inner peripheral surface of the furnace body, and one regenerative burner is installed upstream of the transport direction of the metal strip. The other regenerative burner that forms a pair with is installed downstream of the one regenerative burner. When the two regenerative burners forming a pair are mounted in this way, the combustion exhaust gas generated from one regenerative burner flows spirally at high speed in the annular passage formed between the furnace body and the muffle, and the other Since it reaches the heat storage type burner, the temperature distribution can be further improved and the metal strip can be heated as set.

[0010]

At least a pair of regenerative burners are installed in each divided zone or in each divided unit furnace body, and the combustion exhaust gas generated in each zone or each unit furnace body is regenerated. Since each zone or each unit furnace body is not affected by the combustion exhaust gas generated on the upstream side thereof, it is possible to set any desired temperature distribution in the furnace, and the combustion exhaust gas It also has a high heat recovery rate.

[0011]

1 is a vertical sectional view schematically showing an embodiment of the present invention. A muffle 21 is provided inside the integrally formed furnace body 11.
The heat insulating materials 31 and 32 are attached to the inlet and outlet of the muffle 21 on its circumferential surface, and the metal strip A is continuously conveyed inside the muffle 21. The furnace body 11 is divided into a total of three zones 41, 42, 43, and the furnace body 11 has zones 41, 42, 43.
Two pairs of heat storage type burners 51a and 51b are attached to each of them.

In the zone 41, the regenerative burner 51a
And the heat storage burner 51b form a pair, and the heat storage burner 51a is mounted slightly downstream of the heat storage burner 51b in the transport direction of the metal strip A. Further, the heat storage type burner 52a and the heat storage type burner 52b form a pair, and the heat storage type burner 52a is mounted slightly downstream of the heat storage type burner 52b in the transport direction of the metal strip A. Although the explanation is omitted, in the zones 42 and 43,
The reciprocal relation between the heat storage type burners 53a to 56a and the heat storage type burners 53b to 56b which form a pair respectively is similar.

FIG. 2 is a cross sectional view schematically showing the same embodiment as FIG. Regenerative burner 51 forming a pair in the furnace body 11
a and the heat storage type burner 51b generate these combustion flames in the furnace body 11
It is mounted so as to be injected in the tangential direction of the inner peripheral surface of
Regenerator 61a of the heat storage type burners 51a, 51b,
A common air supply fan 81 is connected to the upstream side of 61b via air supply valves 71a and 72a, and a common exhaust fan 82 is connected to the downstream side thereof via exhaust valves 71b and 72b. It is connected.

Combustion air is supplied from the air supply fan 81 to the regenerator 61a via the air supply valve 71a, preheated to a high temperature by the regenerator 61a, and the regenerative burner 51a.
When the fuel is burnt, the combustion exhaust gas spirally flows at high speed in an annular passage formed between the furnace body 11 and the muffle 21, reaches the regenerator 61b, and is exhausted by the exhaust fan 82 via the exhaust valve 72b. To be done. Heat storage type burner 51
When b is burned, the flow of the combustion air and the combustion exhaust gas is the path of the air supply fan 81 → the air supply valve 72a → the regenerator 61b → the annular passage → the regenerator 61a → the exhaust valve 71b → the exhaust fan 82. . Therefore, when burning the regenerative burner 51a, the valves 71a and 72b are open, and the valves 71b and 72a are closed. The valves 72b and 71a are closed. Although not described, the heat storage type burners 52a to 5 each forming a pair.
6a and the regenerative burners 52b to 56b have the same mutual relationship.

FIG. 3 is a vertical sectional view schematically showing another embodiment of the present invention. A total of three unit furnace bodies 12a to 12c are connected, and a muffle 22 is equipped inside the unit furnace bodies 12a to 12c. At the inlet and outlet of the muffle 22 and the connecting portions of the unit furnace bodies 12a to 12c, heat insulating materials 33 to 38 are attached to the inner peripheral surfaces thereof.
The metal strip B is continuously conveyed in the inside of the unit 2. The furnace body as a whole is composed of a total of three unit furnace bodies 12a to 12c, and a pair of regenerative burners 57a to 59b are attached to each of the unit furnace bodies 12a to 12c.

In the unit furnace body 12a, the regenerative burner 5
7a and the heat storage burner 57b form a pair, and the heat storage burner 57a is mounted slightly downstream of the heat storage burner 57b in the transport direction of the metal strip B. Although the description is omitted, in the unit furnace bodies 12b and 12c, the mutual relationship between the heat storage type burners 58a and 59a and the heat storage type burners 58b and 59b forming a pair is similar, and the heat storage type burners 57a are also the same. ~ 59b mounting positions, the connection relation of the air supply valve, the air supply fan, the exhaust valve and the exhaust fan to the regenerator of each heat storage type burner 57a ~ 59b is the same as in the case of the one embodiment of FIGS. 1 and 2 described above. Has become.

[0017]

As is apparent from the above, according to the present invention described above, at least a pair of regenerative burners are installed in each zone or each unit furnace body, and each zone or each unit furnace body is Since it is not influenced by the combustion exhaust gas generated on the upstream side of them, there is an effect that a desired temperature distribution can be set in the furnace and the heat recovery rate of the combustion exhaust gas is high.

[Brief description of drawings]

FIG. 1 is a vertical sectional view schematically showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing the same embodiment as FIG.

FIG. 3 is a vertical sectional view schematically showing another embodiment of the present invention.

[Explanation of symbols]

11 ... Furnace body, 12a-12c ... Unit furnace body, 2
1, 22 ... Muffle, 31-38 ... Insulation material, 5
1a to 59b ... Heat storage type burners, 61a, 61b ...
・ Regenerator, 81 ... Air supply fan, 82 ...
Exhaust fan

Claims (3)

[Claims] 1. A continuous annealing furnace for metal strips, wherein a furnace is provided with a muffle and a plurality of burners is attached to the furnace body, and the inside of the furnace body is divided into a plurality of zones. A continuous annealing furnace for metal strips, characterized in that at least a pair of regenerative burners are installed in each zone. 2. A continuous annealing furnace for a metal strip in which a muffle is equipped inside a furnace body and a plurality of burners is mounted on the furnace body, wherein the furnace body is composed of a plurality of unit furnace bodies. A continuous annealing furnace for metal strips, characterized in that at least a pair of regenerative burners are installed for each unit furnace body. 3. The continuous annealing for a metal strip according to claim 1, wherein one heat storage burner and the other heat storage burner forming a pair are mounted at positions displaced from each other with respect to the transport direction of the metal strip. Furnace.