JPH07103659A - Continuous heating furnace and heating method - Google Patents

Abstract

PURPOSE:To enable a plurality of groups of steel materials of different heating finishing temperatures to be efficiently heated in the same furnace by a method wherein a plurality of partition walls which can be moved in a longitudinal direction of the furnace are arranged and then combustion burners are arranged at specified distances in a longitudinal direction of the furnace on both side walls of the furnace. CONSTITUTION:A walking beam type heating furnace has some fixed partition walls 2a to 2j and some movable partition walls 3a to 3d at a furnace shell 1. The movable partition walls 3a to 3d are spaced apart by a specific amount in a longitudinal direction of the heating furnace, the wheels 7 of a traveling vehicle are rolled on rails in a moving direction of the heated steel material 21 and moved forward or reaward. One set of two heat accumulative type combustion burners 8a and 8b is arranged between the adjoining partition walls of the fixed partition walls 2a to 2j, each of heat exchanging type combustion burners 8c to 8n is arranged within a combustion region where the movable partition walls 3a to 3d are present, and then the combustion burners 8c to 8n are so controlled as to stop/restart the combustion as the movable partition walls 3a to 3d are moved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a plurality of partition walls movable along the length direction of a continuous heating furnace, and a combustion burner and a suction device are provided on both side walls of the furnace so that the partition wall is movable. The present invention relates to a continuous heating furnace capable of heating a steel material group to be heated between two partition walls in a state where it is hardly affected by combustion control of other heating zones, and a heating method using the continuous heating furnace.

[0002]

2. Description of the Related Art A continuous heating furnace (heat treatment furnace) for heating or heat-treating a steel material while continuously moving it in the furnace.
In general, the inside of the furnace is divided into a plurality of combustion zones along the longitudinal direction from the inlet side, such as pre-tropical zone, heating zone and soaking zone, and the steel material is set at the set temperature set in each combustion zone. Is heated according to.

The plurality of combustion zones are divided by a partition wall, leaving a portion through which the steel material can pass, and each combustion zone is an independent combustion chamber for combustion control. The combustion method in such a continuous heating furnace is one in which combustion burners are provided on both sides in the longitudinal direction of the furnace, and combustion is controlled as an independent combustion zone in a space partitioned by adjacent partition walls (hereinafter referred to as side-burning heating). A furnace, in which a combustion burner is arranged in the direction in which the steel material in the furnace advances or in the opposite direction, and combustion is controlled as an independent combustion zone in the space partitioned by adjacent partition walls (hereinafter referred to as an axial flow heating furnace). There are two types.

In both the side-burning furnace and the axial-flow burning furnace, the combustion exhaust gas after heat exchange with the steel material in each combustion zone is
From the high-temperature zone to the low-temperature zone, the whole amount is released from the furnace bottom (steel material charging side) through the flue to the atmosphere. Although the partition wall described above is of a fixed type, it has been devised that the partition wall is moved in the furnace in the longitudinal direction of the furnace to achieve effects other than the above-mentioned effects.

For example, in the technique disclosed in Japanese Utility Model Laid-Open No. 59-80453, the partition wall is provided so as to be movable in the traveling direction of the steel material to be heated, so that the combustion chamber can be changed according to the change in the fuel supply amount. Since the volume of can be changed to the optimum size for combustion, the thermal efficiency will be improved and the fuel consumption rate will be reduced.

However, in this example, although it is effective in the combustion zone in which the combustion device is arranged, the temperature control in the temperature zone in the latter stage where the combustion device is not arranged is unsuccessful, and the furnace pressure controllability is conventional. It is no different from the method.

Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 57-207110, a partition type partition wall device is inserted between steel materials having different heating finishing temperatures, so that the conventional method is not possible. While it was necessary to heat the steel material group and the rear steel material group at a distance of 40 m, it is said that heating can be performed without a distance.

However, this technique is intended for a heat treatment furnace having a low heating temperature (heating temperature of about 650 ° C.),
Application to a high temperature heating furnace (heating temperature of 1300 to 1350 ° C.) is difficult due to the heat resistant structure, and it takes time and effort to perform processing after the partition wall is taken out of the furnace.

[0009]

In recent years, when a steel material is heated for hot rolling or heat treatment, from the viewpoint of maintaining a high surface quality of the final product and homogenizing the material quality in the same product. It is becoming necessary to control the heating and finishing temperature in steps of 10 ° C.

In order to cope with such a need, in the above-mentioned conventional continuous heating furnace, an appropriate number of partition walls are arranged to narrow the temperature control region to improve controllability. However, it is difficult to make the length of the region correspond to the length of the lot of steel material heated to the same temperature, so heating becomes insufficient or excessive and it is very difficult to heat within a temperature difference of 10 ° C. There is a problem that it is difficult. Further, if a space where no steel material is present is provided between two steel material lots having different heating finish temperatures in an attempt to solve such a problem, a new problem arises that the operating efficiency of the heating furnace is reduced.

Further, in the conventional furnace pressure control in a heating furnace, the furnace pressure control is provided at the furnace outlet so that the pressure at one representative point (soak zone) in the furnace is detected and the value is adjusted to a target value. It controls by opening and closing the damper for the heating furnace, but when the combustion zone of the heating furnace is divided into multiple small combustion zones by the partition wall, the combustion gas in the upstream combustion zone is burned in the downstream side by such control. However, there is a problem that the furnace pressure fluctuation in each combustion zone becomes large and the combustion controllability deteriorates. And such a tendency is that the combustion zone divided by the partition wall
The more you have, the bigger it becomes.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is heated to the same finishing temperature in a continuous heating furnace divided into a plurality of combustion zones by a partition wall. The steel material group can be burned in a combustion zone of a size suitable for the lot length of the steel material group, and since a large amount of combustion gas does not flow in the downstream combustion zone, combustion control in the downstream combustion zone is not disturbed. It is intended to provide a continuous heating furnace.

[0013]

The continuous heating furnace according to the present invention is a continuous heating furnace in which a partition wall divides the combustion zone into a plurality of combustion zones along the longitudinal direction of the furnace. Combustion exhaust gas generated in the partition walls is provided with multiple possible partition walls, and combustion burners are arranged on both side walls of the furnace at predetermined intervals along the longitudinal direction of the furnace to heat the material to be heated. It is provided with a suction device that can discharge most of the outside. In addition to the above, the combustion burner is a heat storage type (with suction device) burner, and a plurality of openable and closable exhaust gas outlets are provided on the ceiling of the furnace along the longitudinal direction of the furnace.

Further, in the heating method for a continuous heating furnace according to the present invention, a group of heated steel materials heated to the same heating finishing temperature is continuously charged into the continuous heating furnace, and the heated steel material group is heated. A movable partition wall is placed in front of and behind, and the front and rear partition walls are moved in conjunction with the movement of the heated steel material group, and the heated steel material group is heated by the regenerative combustion burner between the front and rear partition walls. In addition, the generated combustion exhaust gas is discharged to the outside through the heat storage body of the regenerative combustion burner.

[0015]

When the steel material is heated by the heating method of the present invention using the continuous heating furnace of the present invention, the steel material group in the moving partition wall can be heated independently of the group in the other partition wall.
A steel material group can be heated for each steel material group having a different heating finish temperature, the steel material can be heated to a target temperature, and the operating rate of the furnace does not decrease.

[0016]

EXAMPLE An example in which the present invention is applied to a walking beam type heating furnace will be described with reference to FIG. Figure 1
(A) is a longitudinal sectional view of this walking beam type heating furnace,
FIG. 1B is a cross-sectional view of this walking beam type heating furnace. In this heating furnace, fixed partition walls 2a to 2j and movable partition walls 3a to 3d are arranged in the furnace shell 1. The movable partition walls 3a to 3d are arranged at predetermined intervals in the furnace length direction of the heating furnace, and can move forward and backward with respect to the moving direction of the heated steel material 21 (furnace length direction).

The movable partition walls 3a to 3d have a structure in which the upper part is suspended by a plurality of suspension arms 4 provided at regular intervals in the furnace width direction, and the upper ends of the suspension arms 4 are It is connected to the support member 5 of the traveling device through a groove-shaped opening provided in the furnace ceiling in the furnace length direction. A rail 6 is laid along the furnace length direction outside the furnace ceiling, and wheels 7 of a traveling device roll on the rail 6 to move the movable partition walls 3a to 3d back and forth in the furnace length direction. It is designed to proceed. The groove-shaped opening in the furnace ceiling through which the suspension arm 4 passes is provided with a sealing device so that it can be automatically sealed after the suspension arm 4 passes.

Between the adjacent partition walls of the fixed partition walls 2a to 2j, the regenerative combustion burners 8a and 8 are capable of discharging the combustion exhaust gas while collecting heat through a regenerator.
In the combustion zone where the movable partition walls 3a to 3d are provided, b is a set of two (not necessarily a set of two), and the combustion exhaust gas is also discharged while exchanging heat through the heat exchange section. Heat exchange type combustion burner 8c-8n
Are provided at equal intervals, and fuel is sent through the cutoff valve and the flow rate control valve to heat the heated steel material between the partition walls.

The heat storage type combustion burners 8a and 8b provided between the adjacent partition walls of the fixed partition walls 2a to 2j are combustion controlled so as to always have a constant heating pattern, but the movable partition walls 3a to 3b. The heat storage type combustion burners 8c to 8n in the combustion zone having 3d are movable partition walls 3a to
With the movement of 3d, the combustion burner group control device controls so as to stop the combustion or restart the combustion. This is because when the partition wall comes immediately before the combustion burner, the flame from the combustion burner directly hits the side surface of the partition wall, so avoid this and prevent accidents that occur due to unstable combustion. .

The combustion burner group control is performed by the method shown in the explanatory view of FIG. That is, the initial positions of the movable partition walls 3a to 3d are as follows: the partition wall 3a is in front of the burner, the partition wall 3b is in front of the burner, the partition wall 3c is in front of the burner, and the partition wall 3d is in front of the burner. When in the rearward state, combustion in the A zone, B zone and C zone is
The zone is controlled by the burner, the B zone is controlled by the burner, and the C zone is controlled by the burner.

From such a state, the movable partition walls 3a ...
3d are respectively advanced, the partition wall 3a is in front of the burner, the partition wall 3b is in front of the burner,
The partition wall 3c is in front of the burner, and the partition wall 3d
Changes to the state behind the burner,
The combustion of the newly formed A'zone, B'zone and C'zone is performed by the burner in the A'zone.
The B'zone by the burner
The zone is controlled to be performed by the burner.

The movable partition walls 3a to 3d move forward to the position of the movable partition wall 3b shown in FIG. 1 (a) and move back to the original position, and the movable partition wall 3b.
1 moves forward to the position of the movable partition wall 3c shown in FIG. 1 (a) and retracts to the original position.
The movable partition wall 3d is advanced to the position of the movable partition wall 3d shown in (a) and retracted to its original position, and the movable partition wall 3d is advanced to the position of the extraction port 9 shown in FIG. 1 (a) and retracted to its original position. To do the action. Therefore, the movable partition wall 3a
As 3 and 3b move forward in conjunction with each other, the regenerative combustion burners that contribute to combustion are changed from three of 8c, 8d and 8e to three of 8d, 8e and 8f, and further 8e,
It replaces 3 of 8f and 8g.

A method of continuously heating three steel material groups with different heating finish temperatures of A, B and C (for example, A is 1250 ° C., B is 1100 ° C. and C is 1200 ° C.) by this heating furnace is as follows. Do the following: When the entire amount of the group A has entered between the movable partition walls 3a and 3b, the movable partition walls 3a and 3b are moved along with the movement of the steel material.
Move b. When the rear end of the group A reaches the position where the movable partition wall 3b was originally located, the movable partition walls 3a and 3b are retracted to their original positions.

At this point, the steel material group B is located between the retracted movable partition walls 3a and 3b, and the steel material group A is located between the movable partition walls 3b and 3c. The movable partition walls 3a, 3b and 3c are moved according to the movement of the steel material. When the rear end of the group A reaches the position where the movable partition wall 3c was originally located, and the rear end of the group B reaches the position where the movable partition wall 3b was originally located, the movable partition walls 3a, 3b and 3c.
Back to the original position. At this point, the steel material group C is located between the retracted movable partition walls 3a and 3b, the steel material group B is located between the movable partition walls 3b and 3c, and the steel material group is located between the movable partition walls 3c and 3d. There will be Group A.

The movable partition walls 3a, 3b, 3c and 3d are moved according to the movement of the steel material. The end of the group A reaches the position where the movable partition 3d was located, the end of the group B reaches the position where the movable partition 3c was located, and the end of the group C reaches the movable partition 3b. When the original position is reached, the movable partition walls 3a, 3b, 3c and 3d are retracted to the original position. At this point, the front end of the group A has reached the extraction port 9, so that the groups A, B, and C are sequentially extracted at a predetermined heating finish temperature.

That is, in this heating method, while the movable partition wall 3a reaches the extraction port 9 from the position where the movable partition wall 3a is initially arranged, a steel material group having the same heating finish temperature is affected by the heating of other steel material groups. Since it can be heated without receiving, it can be heated to a temperature extremely close to the target finish temperature. Although the heat storage type burner in which heat storage and suction are periodically repeated has been described above, a suction device capable of sucking almost all the combustion exhaust gas and a general burner may be used.

The combustion exhaust gas generated between the partition walls is stored in the heat storage body of the heat storage type combustion burner, and then 80% or more of the exhaust gas is sucked by the suction fan and is diffused into the atmosphere through the chimney. The remaining flue gas of less than 20% is passed through the steel passage space to the downstream combustion zone to effectively utilize thermal energy.

When the combustion load in the combustion region surrounded by the partition wall becomes too large, the furnace pressure rises abnormally and the combustion state becomes unstable. In such a case, as shown in FIG. 1 (b). As described above, the exhaust gas is discharged to the flue 12 from the plurality of openable and closable exhaust gas discharge ports 10 provided along the longitudinal direction of the furnace on the ceiling part of the furnace until it reaches a predetermined furnace pressure through the damper 11 for controlling the furnace pressure. To do.

In the normal furnace pressure control, the combustion zone divided by the fixed partition wall is shown by the furnace pressure signal from the furnace pressure detector 13 provided in the furnace wall, and the combustion zone divided by the movable partition wall is shown in FIG. As shown in FIG. 3, the movable partition walls 3a to 3d have openings 14a to 14d on one wall surface thereof, and the movable partition walls 3a to 3d
Through holes 15a penetrating through 3d and the suspension arm 4
The furnace pressure control damper 11 is opened / closed by a furnace pressure signal from a furnace pressure detector using 15d. In addition,
Reference numeral 16 in FIG. 1A is a charging port of the furnace.

[0030]

According to the present invention, a plurality of steel material groups having different heating finish temperatures can be efficiently heated to the target temperature.

[Brief description of drawings]

FIG. 1A is a vertical sectional view of a walking beam type heating furnace according to an embodiment of the present invention, and FIG. 1B is a transverse sectional view of the walking beam type heating furnace.

FIG. 2 is an explanatory diagram showing burner group control of a combustion burner.

FIG. 3 is a cross-sectional view showing a through hole for detecting a furnace pressure provided in a movable partition wall.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace shell part of heating furnace 2a-2j Fixed partition wall 3a-3d Movable partition wall 4 Suspending arm 5 Supporting member for traveling device 6 Rail 7 Wheel of traveling device 7 8a-8n Heat exchange combustion burner 9 Extraction port 10 Exhaust gas discharge port 11 Reactor pressure control damper 12 Flue 13 Reactor pressure detector 14a to 14d Opening on one wall surface of the movable partition wall 15a to 15d Through hole

Claims (3)

[Claims] 1. A continuous heating furnace divided into a plurality of combustion zones along a longitudinal direction of the furnace by a partition wall,
A plurality of partition walls movable in the longitudinal direction of the furnace are provided, and combustion burners are arranged on both side walls of the furnace at predetermined intervals along the longitudinal direction of the furnace to heat the material to be heated and the partition walls. A continuous heating furnace that is equipped with a suction device that can discharge most of the combustion exhaust gas generated inside. 2. The combustion burner according to claim 1, wherein the combustion burner is a regenerative combustion burner, and a plurality of openable and closable exhaust gas outlets are provided in an upper portion of a side wall of the furnace along a longitudinal direction of the furnace. Continuous heating furnace. 3. A continuous heating furnace according to claim 1, wherein a group of heated steel materials heated to the same heating and finishing temperature is continuously charged, and a partition wall movable before and after the heated steel material group is provided. The front and rear partition walls are moved in conjunction with the movement of the heated steel material group, and the heated steel material group is heated by the heat storage type combustion burner between the front and rear partition walls, and the generated combustion exhaust gas is stored in the heat storage type. A heating method using a continuous heating furnace, characterized in that the heat is discharged to the outside through a heat storage body of a combustion burner.