JP2000282137A - Soaking method and soaking furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heating quality of a steel ingot and also the treating capacity by selecting an optimum heating operation according to the kind of the steel ingot. SOLUTION: In the front part at an one side in the longitudinal direction of a furnace body 32, one set of main burner 34 is disposed at almost center position in the width direction. In the rear part at the other side in the longitudinal direction of the furnace body 32, two sets of auxiliary burners 36 are disposed so as to be mutually apart in the width direction. Each combustion capacity in both auxiliary burners 36, is set to <=1/2 of the combustion capacity in the main burner 34, and two sets of the auxiliary burners 36 and one set of the main burner 34 are constituted so as to have the relation of a pair in a regenerator burner system. In the case of charging plural steel ingots 14 in the vertically laying state in the furnace, only the main burner 34 is used to heat the steel ingot group, and in the case of charging plural steel ingots 14 in the horizontally laying state in the furnace, the main burner 34 and the auxiliary burners 36 are alternately used to heat the steel ingot group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soaking method and a soaking furnace capable of selecting a regenerative burner combustion system (hereinafter referred to as "regenerative burner system") to heat a steel ingot.

[0002]

2. Description of the Related Art A slab manufactured by casting molten steel into a mold,
When a steel ingot such as a billet is taken out of a mold and then rolled, as a pre-process, there is a heat equalizing operation for making the temperature between the inside and the outside of the steel ingot close to uniform. As shown in FIG. 5, the heat equalizing furnace used for this heat equalizing operation has a single burner 12 disposed at one front portion in the longitudinal direction of the furnace body 10 and faces the width direction inside the furnace body 10. A configuration in which a plurality of steel ingots 14 are loaded on the left and right inner side wall surfaces in a state where the plurality of steel ingots 14 are placed upright at a predetermined interval in the longitudinal direction (vertical installation state), and the burners 12 are burned to heat each steel ingot 14 Have been.

In the above soaking furnace, as shown in FIGS. 5 (a) and 5 (b), the flame of the burner 12 does not directly hit the steel ingot 14, as shown in FIGS. The burner 12 is disposed substantially at the center and above the upper end of the steel ingot 14. However, in the configuration in which one burner 12 is disposed in the front part of the furnace body 10 as described above, the temperature difference between the front and rear and up and down in the furnace is large, and a kind of a type having good rolling workability such as carbon steel is used. There is no problem when heating the steel ingot 14, but JIS SUS 30
In the case of heating a steel ingot 14 that is difficult to roll, such as No. 3 or JIS SKD 11, there is a problem that uneven heating may hinder the rolling in the subsequent process. Therefore, when heating the steel ingot 14 that is difficult to be rolled, when the twelve steel ingots 14 are charged inside the furnace body 10 as shown in FIG. After taking out the six ingots 14 on the side, an extremely complicated operation of repeating the process of moving the remaining six ingots 14 to the rear and heating again was performed.

Here, in the above-mentioned conventional soaking furnace, the combustion efficiency by the burner is low and the energy loss is large. Therefore, a soaking method using a regenerative burner system has been proposed. This is a pair of two burners each having a heat storage body, and is configured by a switching valve for fuel, air, and exhaust gas, an air blower for thermal firing, an exhaust fan, and a control device for controlling them. In this system, when one burner is burning, the combustion exhaust gas is exhausted from the other burner to heat the regenerator. Next, by switching between combustion and exhaust of the pair of burners, the amount of heat stored in the heat storage body is recovered by the combustion air and returned to the combustion chamber. By repeating this switching in a short cycle of several tens of seconds to several minutes, the combustion air is preheated to a high temperature, and the combustion is performed while recovering waste heat with high efficiency.

The arrangement of burners in a soaking furnace using the regenerating burner system may be, for example, as shown in FIG. That is, the first burner 1 is provided at the front of the furnace body 10.
6 and the third burner 20 are spaced apart in the width direction, and the second burner 18 and the fourth burner 22
Are arranged apart in the width direction, and the first burner 16 and the second burner 18 and the third burner 20 and the fourth burner 22 facing each other are formed as a pair. 4 burners 1
The combustion capacities of 6, 18, 20, and 22 are set to be the same.
During the combustion of the first burner 16 and the fourth burner 22, the operation is performed to exhaust the combustion exhaust gas from the paired second burner 18 and the third burner 20 to heat the regenerator,
During the combustion of the burner 18 and the third burner 20, an operation of heating the regenerator by exhausting the combustion exhaust gas from the paired first burner 16 and fourth burner 22 is performed.

[0006]

In the soaking furnace using the regenerative burner system, since the temperature before and after the inside of the furnace body 10 can be made substantially uniform, as shown in FIG. By loading the steel ingot 14 on the hearth 24 of the furnace body 10 at a predetermined interval in the longitudinal direction in a state of being laid down (sideways), the steel ingot 14 can be uniformly heated. That is,
This is suitable for heating a steel ingot 14 of a type that is difficult to roll. However, when a plurality of steel ingots 14 are charged in a horizontal state, the number of steel ingots 14 that can be processed at one time is small, and a type of steel ingot with good rolling workability that does not require uniformity of furnace temperature is required. There is a disadvantage that the processing capacity when heating 14 is reduced. In addition, in the soaking furnace of the burner arrangement shown in FIG.
When a steel ingot 14 of a type having good rolling workability is charged in a vertical state, the flame is applied to the ingot 14 because the burners 16, 18, 20, and 22 are arranged close to the side walls. There is a problem that it hits directly and causes partial overheating, so charging in a vertical position cannot be adopted.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems inherent in the prior art, and has been proposed in order to solve the problem in a suitable manner. It is an object of the present invention to provide a soaking method and a soaking furnace capable of improving the heating quality of a steel ingot and improving the processing capacity.

[0008]

[MEANS FOR SOLVING THE PROBLEMS]
In order to appropriately achieve the intended purpose, the heat equalizing method according to the present invention comprises charging a plurality of steel ingots inside a furnace body in the longitudinal direction with a distance therebetween, and regenerating these steel ingot groups. A method of equalizing heat that can be heated using a burner combustion system, wherein a plurality of steel ingots are charged vertically along both side walls facing the width direction inside the furnace body. In the case where a plurality of steel ingots are charged in a horizontal state on the hearth in the furnace, by burning only the main burner arranged in a position where the flame does not directly hit the steel ingot in the direction and heating the steel ingot. Is characterized in that the combustion capacity is smaller than that of the main burner, and a plurality of sub-burners arranged in the width direction at the other end in the longitudinal direction of the furnace body and the main burner are alternately burned to heat the steel ingot group. And

[0009] In order to solve the above-mentioned problems and appropriately achieve the intended purpose, a soaking furnace according to another invention of the present application includes a plurality of steel ingots spaced apart in a longitudinal direction inside a furnace body. A soaking furnace capable of heating these ingot groups using a regenerative burner combustion system, and a main burner disposed on one side of the furnace body facing the longitudinal direction,
A plurality of sub-burners, which are arranged in the width direction on the other side opposite to the longitudinal direction of the furnace body and have a smaller combustion capacity than the main burner, and according to a state of charging the steel ingot into the furnace body. And a control device for controlling combustion and stop of the main burner and the sub burner.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a soaking method and a soaking furnace according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of a heat equalizing furnace according to an embodiment. A furnace body 32 of the heat equalizing furnace 30 has one side (front part) in a longitudinal direction (front-rear direction) thereof. In addition, one main burner 34 is arranged at a substantially central position in the width direction. Further, two sub-burners 3 are provided on the other side (rear part) of the furnace body 32 in the longitudinal direction.
6, 36 are spaced apart in the width direction with the approximate center in the width direction interposed therebetween. The combustion capacity of each of the sub-burners 36, 36 is set to about 1/2 or less of the combustion capacity of the main burner 34, respectively.
The two sub-burners 36, 36 and one main burner 34
It is configured to have a pair relationship in the regenerative burner system. When the main burner 34 is burning, the sub-heat storage bodies 76, 76 (described later) are heated by the combustion exhaust gas while stopping the combustion of the two sub-burners 36, 36,
When the two sub-burners 36, 36 are burning, control is performed so that the main heat storage 74 (described later) can be heated by the combustion exhaust gas while the combustion of the main burner 34 is stopped. The steel ingot 14 is placed in the furnace body 32 by selecting one of a horizontal state (see FIG. 1) and a vertical state (FIG. 2) according to its type.

As shown in FIG. 2 (a), the main burner 34 has a flame between the two steel ingot groups that are vertically installed along both side walls facing the width direction inside the furnace body 32. And the three burners 34, 3
As shown in FIG. 2 (b), the arrangement height positions of the cylinders 6, 36 are located above the upper end of the group of steel ingots charged in the vertical position, and the flame of each burner 34, 36, 36 It does not hit the mass directly. The combustion capacity of the main burner 34 is such that by burning the main burner 34 alone, the plurality of steel ingots 14 charged inside the furnace body 32 can be heated with the same level of efficiency as in the past. Set to value.

FIG. 3 shows a schematic configuration of a regenerative burner system employed in the heat equalizing furnace 30 according to the embodiment. A main fuel branch pipe 40 and a sub fuel branch pipe 42 branch from a fuel supply pipe 38 connected to a fuel supply source (not shown),
A main fuel branch pipe 40 is connected to the main burner 34, and a sub fuel branch pipe 42 is connected to the sub burners 36, 36, and a main fuel switching valve 44 interposed correspondingly to each branch pipe 40, 42. The fuel supply from the fuel supply source is selectively supplied to the main burner 34 or the sub-burners 36 by controlling the switching of the sub-fuel switching valve 46 by the control device 48 shown in FIG. In addition, from the air supply pipe 52 connected to the blower 50, the main air branch pipe 54 and the sub air branch pipe 5 are connected.
6, the main air branch pipe 54 is connected to the main burner 34, and the sub air branch pipe 56 is connected to the sub burner 3
6 and 36, the main air switching valve 58 and the sub air switching valve 60, which are interposed correspondingly in the branch pipes 54 and 56, are switched by the control device 48 so that the combustion air from the blower 50 is controlled. The main burner 34 or the sub burners 36, 36 are selectively supplied.

Further, a main exhaust pipe 62 connected to the main burner 34 and a sub-exhaust pipe 64 connected to the sub-burners 36, 36 form a main exhaust pipe 68 connected to an exhaust fan 66.
The main exhaust switching valve 70 and the sub-exhaust switching valve 72 interposed correspondingly to the respective exhaust pipes 62 and 64 are switched by the control device 48 while the exhaust fan 66 is operated. That is, the primary burner 34 or the secondary burner 36,
36, the exhaust gas is selectively exhausted.

A main heat storage body 74 such as a ceramic ball or a honeycomb body is disposed at a supply / exhaust portion of the main burner 34 to which the main air branch pipe 54 and the main exhaust pipe 62 are connected, and a sub burner. A sub heat storage body 76 such as a ceramic ball or a honeycomb body is disposed in a supply / exhaust portion to which the sub air branch pipe 56 and the sub exhaust pipe 64 are connected. And each heat storage body 74,76
When the corresponding main burner 34 or sub-burner 36, 36 has stopped burning, the amount of heat stored by the combustion exhaust gas generated by the combustion of the other sub-burner 36, 36 or main burner 34 is recovered by combustion air, and It works to return to within.

The control device 48 shown in FIG. 4 includes, as described above, the main fuel switching valve 44, sub fuel switching valve 46, main air switching valve 58, sub air switching valve 60, main exhaust switching valve 70, sub exhaust The switching valve 72 is controlled to open and close. Then, in the control device 48 of the embodiment, when heating the steel ingot 14 of a type that is difficult to roll, the combustion of the main burner 34 and the sub-burners 36, 36 and the stop of the combustion are performed at intervals of several tens seconds to several minutes. In order to heat the ingot 14 of a type having good rolling workability, the opening and closing control of each valve is performed so that only the main burner 34 is burned. Is done.

[0017]

Next, the operation of the soaking furnace according to the above embodiment will be described in relation to the soaking method. When heating the steel ingot 14 of a type that is difficult to be rolled in the soaking furnace 30, as shown in FIGS. 1A and 1B, a large number of steel ingots 14 are 33 is placed horizontally. At this time, the switching device 44,
The operation in which the switching of 46, 58, 60, 70, 72 is controlled to stop the combustion of both sub-burners 36, 36 and heat the sub-heat storage bodies 76, 76 with the combustion exhaust gas while the main burner 34 is burning. The operation of stopping the combustion of the main burner 34 and heating the main regenerator 74 with the combustion exhaust gas in a state where both sub-burners 36, 36 are burned is performed alternately at intervals of several tens seconds to several minutes. Is repeated as follows. That is, by operating the above-mentioned regenerative burner system properly, each burner 3
4,36,36 enables high heating with high combustion efficiency, and the steel ingot 14 can be heated uniformly with high heating quality. Therefore, the steel ingot 14 taken out from the soaking furnace 30 can be satisfactorily rolled in the subsequent step. The heat storage elements 74, 76, 76
In this case, high-temperature combustion exhaust gas and combustion air alternately flow in a short cycle to perform direct heat exchange, so that a significant improvement in heat recovery efficiency can be achieved, and energy is saved.

Next, when heating the steel ingot 14 having good rolling workability in the soaking furnace 30, a large number of steel ingots 14 are placed on the inner side wall surfaces of the furnace body 32 as shown in FIG. Along the way, insert it vertically. At this time, the switching valves 44, 46, 58, 60, 70 and 72 are controlled to be switched by the control device 48, so that only the main burner 34 is burned and the steel ingot 14
The operation of heating is performed. As described above, since the main burner 34 is disposed substantially above the upper end of the group of steel ingots in the vertical state at the approximate center in the width direction, the flame of the main burner 34 does not directly hit the group of steel ingots. The occurrence of partial overheating is prevented.

That is, in the heat equalizing furnace 30 of the embodiment, the main burner 34 and the sub-burner according to the charging state (vertical state, horizontal state) in the furnace body 32 according to the type of the steel ingot 14. By controlling the combustion / suspension of 36, 36 by the control device 48, the ingot 14 of a type difficult to be rolled can be uniformly heated to improve the heating quality, and the type of steel ingot having good rollability can be improved. In the steel ingot 14, a large amount can be processed at a time, and the processing capacity can be improved.

The techniques of the soaking method and the soaking furnace described in the embodiments can be applied to a heating furnace, a heat treatment furnace and the like.

[0021]

As described above, in the heat equalizing method and the heat equalizing furnace according to the present invention, the control of the burning / stopping of the plurality of burners in accordance with the state of charging different types of steel ingots into the furnace body. Thus, heat treatment under optimal conditions can be performed. For example,
For ingots of a type that are difficult to roll, it is possible to heat the ingot uniformly and improve the heating quality by firing the primary and secondary burners alternately and operating the regenerative burner system properly. . In addition, when heating ingots of a type with good rolling workability, many ingots can be loaded into the furnace vertically at the same time without overheating, improving the processing capacity. I can do it.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a case where a steel ingot having difficulty in rolling workability is heated in a heat equalizing furnace according to a preferred embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating a soaking furnace according to an example in which a steel ingot having good rolling workability is heated.

FIG. 3 is a schematic configuration diagram of a regenerative burner system employed in the soaking furnace according to the embodiment.

FIG. 4 is a control block diagram of the soaking furnace according to the embodiment.

FIG. 5 is a schematic configuration diagram of a soaking furnace according to a conventional technique.

FIG. 6 is a schematic configuration diagram of a soaking furnace according to a conventional technique employing a regenerative burner system.

[Description of Signs] 14 Steel Ingot 32 Furnace Body 33 Hearth 34 Main Burner 36 Secondary Burner 48 Controller

Claims (4)

[Claims] 1. A plurality of steel ingots (14) are charged into a furnace body (32) at a distance in a longitudinal direction thereof, and the steel ingots can be heated using a regenerative burner combustion system. In the soaking method, when a plurality of steel ingots (14) are charged in a vertically placed state along both side walls facing in the width direction inside the furnace body (32), the length of the furnace body (32) is increased. Only the main burner (34) arranged at a position where the flame does not directly hit the steel ingot in the direction is heated to heat the steel ingot, and placed horizontally on the hearth (33) in the furnace body (32). When a plurality of steel ingots (14) are charged in the condition,
(34) a plurality of sub-burners (36, 36) having a combustion capacity smaller than that of the furnace body (32) and spaced apart in the width direction at the other longitudinal direction of the furnace body (32)
A soaking method characterized by heating a group of ingots by alternately burning a main burner (34). 2. A plurality of steel ingots (14) are charged into a furnace body (32) at a distance in a longitudinal direction thereof, and these steel ingots can be heated using a regenerative burner combustion system. A soaking furnace, a main burner (34) disposed on one side of the furnace body (32) facing the longitudinal direction, and a width on the other side facing the longitudinal direction of the furnace body (32). A plurality of sub-burners (3) having a combustion capacity smaller than that of the main burner (34).
6, 36), and controls the combustion / stop of combustion of the main burner (34) and the sub-burner (36, 36) according to the state of charging the steel ingot (14) into the furnace body (32). A soaking furnace characterized by comprising a control device (48). 3. The combustion capacity of each sub-burner (36) is about one of the combustion capacity of the main burner (34).
The heat equalizing furnace according to claim 2, wherein the temperature is set to not more than / 2. 4. The main burner (34) is located at a position where a flame faces between two steel ingot groups that are vertically inserted along both side walls facing the width direction inside the furnace body (32). The heat equalizing furnace according to claim 2 or 3, wherein