JPH07118753A - Heating method of heating furnace - Google Patents

Abstract

PURPOSE:To uniformly heat a steel billet in high heat efficiency in a short time by changing many sets of burners in a heating furnace for combustion and for heat storage, at the time of heating plural steel billets. CONSTITUTION:Plural round billets W are carried on a hearth 2 of the heating furnace 1 and uniformly heated without oxidizing the round billet W by reducing combustion flame F1 produced by incomplete combustion with the burners 3a, 3b in the heat storage type burner group 3a, 3b, 3c, 3d arranged so as to face both sides of the inner walls of the heating furnace 1. As the combustible components such as CO, H2, etc., exist in the waste gas used to heating, the heat storage body in the burner is heated by burning with the burners 3c, 3d to store the heat. Successively, after passing the fixed time, the burners 3a, 3b are changed over to the burners 3c, 3d, and the fuel and the air are heated with the high temp. heat storage bodies in the burners 3c, 3d and burnt, and the combustion flame F1 is generated to heat the billet W. The burners 3a, 3b are used for the heat storage and the burner group is alternately changed over for combustion and for heat storage and operated, and the billet W is uniformly heated in the high heat efficiency within short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention divides a furnace into a plurality of combustion zones, and uses one or more pairs of regenerative burners for alternately combusting fuel and discharging exhaust gas through a regenerator. The present invention relates to a heating method of a heating furnace arranged facing or adjacent to.

[0002]

2. Description of the Related Art In recent years, in order to increase the thermal efficiency of industrial furnaces such as heating furnaces and heat treatment furnaces (hereinafter collectively referred to as heating furnaces), the inside of the furnace is divided into a plurality of combustion zones, and the combustion of fuel and the heat storage body are performed. There is used a heating furnace in which one or more pairs of regenerative burners that alternately discharge exhaust gas through are arranged opposite or adjacent to the furnace wall of each zone.

Such a heating furnace is disclosed in, for example, Japanese Patent Laid-Open No. 2-1.
It is disclosed in Japanese Patent No. 0002. When heating an object to be heated in this heating furnace, one of the pair of burners is burned and the combustion exhaust gas generated in the other is discharged through the heat storage body. The combustion of the corresponding pair of burners and the allocation of exhaust gas discharge are exchanged at regular intervals, and at the time of combustion, the combustion air is passed through the heat storage body, and the combustion air is preheated by the heat held by the heat storage body for use.

[0004]

However, in the above-described heating furnace disclosed in Japanese Unexamined Patent Publication No. 2-10002, the unheated object is placed directly on the hearth, so that the surface of the object to be heated on the hearth side. Radiant heat from the flame and furnace wall is not transmitted,
A temperature difference occurs between the front and back surfaces of the object to be heated during heating. The temperature difference in the non-heated material generated in the heating process causes nonuniform rolling in the rolling process. There is a problem that it is necessary to lengthen the heating time in order to make the temperature of the object to be heated uniform.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to provide a heating method capable of uniformly heating an object to be heated in a short time.

[0006]

The above-mentioned object is to divide the furnace into a plurality of combustion zones, and to provide one or more pairs of regenerative burners in each zone for alternately combusting fuel and discharging exhaust gas through a regenerator. It is achieved by arranging it facing or adjacent to the furnace wall, incompletely combusting the fuel by the regenerative burner, and directly applying the generated flame directly to the object to be heated or while heating it while existing in the vicinity of the object to be heated. .

In addition to the above construction, a burner different from the regenerative burner burns the fuel at an air-fuel ratio such that oxygen remains in the flue gas, and the oxygen in the flue gas burns the regenerative burner. The thermal efficiency can be increased by burning the unburned components in the exhaust gas.

Similarly, thermal efficiency can be increased by supplying air from an air supply nozzle provided in the combustion zone to burn unburned components in the combustion exhaust gas of the regenerative burner.

[0009]

[Function] By incompletely burning the fuel, the flame becomes a long flame and the flame temperature becomes low. Therefore, even if the flame is directly applied to the object to be heated or the flame is present in the vicinity of the object to be heated, the temperature of the object to be heated does not rise excessively and is not melted by that. Moreover, since the flame is reducing, it does not oxidize the object to be heated. Radiant heat from the flame is transmitted to the hearth side of the heated object by directly applying the flame to the heated object or by allowing the flame to exist near the heated object.
The object to be heated is heated uniformly.

Further, in the present invention, since the regenerative burner is used as the burner, the pair of burners are burned alternately. Therefore, since the flame does not continuously exist in a certain place, only a part of the material to be heated is prevented from being heated, and the effect of uniform heating becomes more remarkable.

In addition to this, when the unburned components in the exhaust gas of the regenerative burner are burned by the combustion exhaust gas of another burner burned at an excess air ratio or the air supplied from the air supply nozzle, the thermal efficiency is improved. Can be increased.

[0012]

EXAMPLE A first example of a heating method for a heating furnace according to the present invention will be described with reference to an explanatory view of FIG. 1 for heating a round billet. The round billet W is placed on the hearth 2 of the heating furnace 1 and sequentially conveyed in the furnace. On both side walls of the heating furnace 1, heat storage type burner groups 3a, 3b, 3c and 3d for arranging combustion start and combustion stop at the same timing are arranged. When the burner group 3a is burning, the burner group 3c discharges the exhaust gas, and when the burner group 3c is burning, the burner group 3a discharges the exhaust gas. Thus, the burner group 3a and the burner group 3c are discharged. Burn alternately. Further, the burner group 3b and the burner group 3d are also designed to alternately burn.

Then, while considering the relative positions of the round billet W and each burner, a group of 3a, 3c burners, or 3
b, burn 3d burner group. This is to prevent the combustion flame from colliding with the end face of the billet W and overheating the end face. As the pitch of burner arrangement becomes finer, the combustion flame can be placed between billets W and billet W to prevent overheating of the end surface. However, if the pitch is set to 1/2 of billet placement pitch, the equipment becomes large or complicated. Not suitable. In FIG. 1, combustion is performed by a pair of burner groups 3a and 3c. The combustion burner group is 3a and the non-combustion burner group is 3c.

In the present embodiment, the combustion switching is performed at intervals of 30 seconds, and the combustion switching of the 3a, 3c burner group or the 3b, 3d burner group is determined by the transport speed, but it is about 10 on average.
Burning and non-burning are switched in minutes. The combustion flame is an incomplete combustion flame and prevents the billet W from being overoxidized. Further, the combustion order of the primary combustion burner groups 3a, 3b, 3c and 3d may be any combination such as opposing burners, burners positioned diagonally in front, or burners diagonally arranged in the combustion chamber. In FIG. 1, reference numeral F ₁ is a combustion flame (primary combustion flame).

Next, a second embodiment of the heating method of the heating furnace of the present invention will be described with reference to the explanatory view of FIG. 2 for heating a round billet. In the case of this heating method, 2
The unburned components (CO 2 , H2, etc.) to form a complete combustion flame. As a result, the fuel injected into the combustion chamber is completely burned in the combustion chamber, and energy is not wasted. Reference numeral F _{2 in} FIG.
Is the secondary combustion flame.

The secondary combustion burner may be a side burner type installed on the side wall of the combustion chamber, a roof burner type installed on the ceiling, or a burner arrangement installed on both the side wall and the ceiling. Further, the combustion order of the secondary combustion burners may be any combination such as opposing burners, burners positioned diagonally in front, or burners diagonally arranged in the combustion chamber.

Next, a third embodiment of the heating method for the heating furnace of the present invention will be described with reference to the explanatory view of FIG. 3 for heating a round billet. In the case of the present embodiment, high temperature air is supplied into the furnace from the air supply nozzle groups 5a, 5b, 5c and 5d provided on the furnace wall 1a of the heating furnace 1, and the primary combustion burner groups 3a, 3b, 3c and 3d. Unburned components (CO, H2, etc.) generated by combustion are burned to form a complete combustion flame. As a result, the fuel injected into the combustion chamber is completely burned in the combustion chamber, and energy is not wasted. The location of the air supply nozzle groups 5a, 5b, 5c and 5d is not limited to the side wall, but may be provided on the ceiling.

[0018]

As is apparent from the above description, since the present invention is configured as described above, the flame of the regenerative burner is made to directly impinge on the object to be heated or the flame near the object to be heated. By the presence of, it becomes possible to uniformly heat the object to be heated, and it is possible to prevent surface oxidation of the object to be heated.

Further, energy saving can be achieved by afterburning unburned components (CO, H2) generated by incomplete combustion of the heat storage type burner and completely burning it in the combustion chamber.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of a heating method for a heating furnace according to the present invention.

FIG. 2 is an explanatory view of a second embodiment of the heating method of the heating furnace of the present invention.

FIG. 3 is an explanatory view of a third embodiment of the heating method of the heating furnace of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 furnace body 2 hearth 3a-3d primary combustion burner group 4a-4d secondary combustion burner group 5a-5d air supply nozzle group 11 fuel nozzle 12 air nozzle F1 primary combustion flame F2 secondary combustion flame W heated object

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F27B 9/36 F27D 7/02 A 7727-4K

Claims (3)

[Claims] 1. A furnace is divided into a plurality of combustion zones, and one or more pairs of regenerative burners for alternately combusting fuel and discharging exhaust gas through a heat storage body are provided adjacent to or adjacent to a furnace wall in each zone. A heating method for a heating furnace, wherein the heating furnace is arranged and the fuel is incompletely combusted by the regenerative burner, and the generated flame is directly applied to the object to be heated or heated while existing near the object to be heated. 2. A burner different from the regenerative burner burns fuel at an air-fuel ratio such that oxygen remains in the flue gas, and oxygen in the flue gas causes unburned flue gas in the flue gas of the regenerative burner. The method for heating a heating furnace according to claim 1, wherein the components are burned. 3. The heating method for a heating furnace according to claim 1, wherein air is supplied from an air supply nozzle provided in the combustion zone to burn unburned components in the combustion exhaust gas of the regenerative burner. .