JPH09256055A - Continuous heating method and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent of reduce the development of skid mark in a small-scaled apparatus without aggravating the requirement unit of fuel, at the time of heating a metallic material of steel, etc., with a continuous heating furnace. SOLUTION: A resistant exothermic body is arranged on the upper surface of a skid beam 2 to execute the electric heating. A mixing chamber 12 for mixing the fuel and the air is arranged in the skid beam 2, and fuel and the air are jetted through a porous panel 13 arranged on the upper surface of the skid beam 2 to form combustion flame 17. A double tube is arranged in the skid beam 2, and the fuel and the air are introduced respectively into the inner tube and the outer tube of the double tube, and the fuel is jetted from opening holes arranged in the inner tube and burnt in the tube. This skid beam can be applied in an arbitrary necessary position of the skid beam over the whole length from the inlet to the outlet of the furnace and the skid mark can be prevented or remarkably be reduced. At the time of rolling and executing the heat treatment to the metallic material of steel, etc., the operation is stabilized and the product quality is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, when a metal material such as steel is heated while being supported by a skid beam in a heating furnace while being transferred, does not generate skid marks in the material,
Alternatively, it relates to a method and a device for mitigation.

[0002]

2. Description of the Related Art As a heating furnace for hot-rolling or heat-treating metal materials such as steel slabs such as slabs and billets, there is used a continuous heating furnace for passing a material to be heated one after another to a predetermined temperature. To be done. In this furnace, since the material to be heated is supported and transferred by the skid beam, a low temperature portion called a skid mark is generated in the portion in contact with the rail or the portion shielded from the heating source by the rail. Conventionally, various improvement measures have been taken, but in recent years,
A method and apparatus for locally heating the skid mark portion in a heating furnace have been proposed.

In Japanese Patent Laid-Open No. 5-179339, a combustion device for heating skid marks is provided on the extraction side of the heating furnace.
An apparatus and method have been proposed in which the temperature of a material to be heated is measured and combustion control is performed with a fuel flow rate and an air flow rate that minimize the temperature difference between a high temperature portion and a low temperature portion that is a skid mark portion. However, even if only the extraction side of the furnace is heated, there is a limit to the skid mark reduction, and such a combustion device cannot be installed in a high temperature part in the furnace.

Further, in Japanese Patent Laid-Open No. Sho 60-200908, a combustion radiant tube having a large number of combustion gas ejection holes is attached to both sides of the outer circumference of a skid beam, and a combustor is provided at one end of the combustion radiant tube. There has been proposed a heating furnace in which the combustion gas injection holes are provided so as to face the skid mark portion of the material to be heated. However, when the combustion radiant tubes are attached to both sides of the skid beam, there is a problem that the equipment becomes large in scale, and the cost and work load for installation and maintenance increase. Therefore, in the example of the publication, a combustion radiant tube is installed only in the skid beam near the exit of the heating zone of the continuous heating device consisting of the preheating zone, the heating zone, and the soaking zone, and there is a limit to the skid mark reduction. There is.

[0005]

SUMMARY OF THE INVENTION According to the present invention, when a metal material such as steel is heated in a continuous heating furnace, a small-scale device does not deteriorate the fuel consumption rate and does not generate or reduce skid marks. It is an object of the present invention to provide a method and device for doing the above.

[0006]

In order to achieve the above object, the first invention method of the present invention is a continuous heating method in which a material to be heated is supported by a skid beam in a heating furnace and transferred while being heated by a burner combustion flame. In the method, a resistance heating element is provided on the upper surface of the skid beam to electrically heat the skid beam, and the vicinity of the skid mark is heated by radiative heat transfer.

The second invention method is a continuous heating method in which a material to be heated is supported and transferred by a skid beam in a heating furnace and heated by a burner combustion flame, and a mixing chamber for fuel and air is provided inside the skid beam. Then, a mixture of fuel and air is jetted through a porous panel disposed on the upper surface of the skid beam to form a combustion flame, and the vicinity of the skid mark is heated by radiative heat transfer from the combustion flame. It is a characteristic continuous heating method.

A third invention method is a continuous heating method in which a material to be heated is supported and transferred by a skid beam in a heating furnace and heated by a burner combustion flame, and a double pipe is internally provided in the skid beam. Radiation from the surface of the double pipe heated by introducing fuel into the inner pipe of the double pipe and introducing air into the outer pipe, ejecting the fuel from the opening provided in the inner pipe, and burning the fuel inside the double pipe. The continuous heating method is characterized in that the vicinity of the skid mark is heated by heat transfer.

The first invention apparatus of the present invention for achieving the above object is a continuous heating apparatus for heating a material to be heated by a burner combustion flame while supporting and transferring the material to be heated by a skid beam in the heating furnace. In the continuous heating device, a burner is provided on the wall and plate-shaped resistance heating elements are provided on both sides of the rider of the skid beam so as not to contact the rider.

The second invention apparatus is a continuous heating apparatus in which a material to be heated is supported and transferred by a skid beam in a heating furnace and heated by a burner combustion flame while a burner is provided on the furnace wall and the upper surface of the skid beam is provided. A continuous heating device, wherein a porous panel is provided in the mixing chamber, a mixing chamber is provided in the skid beam below the panel, and a fuel introducing pipe and an air introducing pipe are connected to the mixing chamber.

A third invention apparatus is a continuous heating apparatus in which a material to be heated is supported and transferred by a skid beam in a heating furnace and is heated by a burner combustion flame while a burner is provided on a furnace wall and the skid beam is provided in the skid beam. Continuous heating characterized in that a heavy pipe is internally provided, a fuel introduction pipe is connected to the inner pipe of the double pipe and an opening is provided, and an air introduction pipe is connected to the outer pipe of the double pipe. It is a device.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention is applied to a continuous heating furnace as shown in FIG. In FIG. 1, a material to be heated 1 is a skid beam 2 of a walking beam system.
N which is supported by the partition wall and is partitioned by the partition wall 5 from left to right in the figure.
o. No. 1 heating zone, No. 1 No. 2 heating zone ... While being sequentially transferred through the eight heating zones, they are heated by the combustion flame from the burner 6. The skid beam 2 is composed of a fixed beam and a movable beam, and the material to be heated 1 is moved up and down and moved by the movable beam. Reference numeral 3 is a fixed beam column, and 4 is a movable beam column.

The method of the present invention is not limited to this example, but can be applied to a pusher system in which a material to be heated is slid on a skid beam and transferred. Further, it can also be applied to a heating furnace having a burner 6 provided in the length direction of the furnace as shown in FIG. Furthermore, in the method of the present invention,
As the burner 6, it is also possible to employ a burner 6 that alternately switches one pair facing each other between combustion and heat storage.

According to the first invention method, in such a continuous heating furnace, as shown in the example of FIG. 3, resistance heating elements 9 and 10 are provided on the upper surface of the skid beam 2 to heat them electrically. Above the skid beam 2, there is usually a rider 8 in contact with the material to be heated. In this example, resistance heating elements 9 are provided on both sides of the rider 8 and the resistance heating element 1 is provided between the divided riders 8.
0s are provided at intervals so as not to contact the riders 8. Then, electrodes 11 are attached to the end portions of the resistance heating elements 9 and 10, embedded in the skid beam 2, and electrically heated.

A resistance heating element 10 between the riders 8 is provided.
Is provided as necessary and may not be provided if the skid mark is mild due to conditions such as the heating temperature of the material to be heated. Each rider 8 is directly cooled by the water passing through the cooling water pipe 7. The cooling water is supplied and drained through the fixed beam support column 3 and the movable beam support column 4.

As the resistance heating elements 9 and 10, plate-shaped heating elements used in a normal resistance heating furnace or the like can be adopted. It can be selected from various heating elements such as metal type and non-metal type according to the type of material to be heated, heating conditions, etc., but for heating the slab before rolling the steel material, it is inert in the furnace atmosphere. Considering the degree and the specific resistance value, it is preferable to employ an alumina carbide type or nitride type resistance heating element. Further, the total length of the resistance heating element is determined according to the required heating amount, and it is preferable that the resistance value of each heating element is about 1Ω. If the resistance value is too large, a large power supply for energization is required, and if it is too small, the required heat generation amount cannot be obtained.

According to the method of the first invention, the portion where the skid mark is generated in the material to be heated 1 is heated by the resistance heating element, or the radiation cooling of the skid beam 2 is prevented. And, because of its relatively simple structure, it can be applied to any fixed and movable skid beams in heating zones and soaking zones, and can be applied over the entire length if necessary. Therefore,
Skid marks disappear or are significantly reduced.

In the second invention method, as shown in the example of FIG. 4A, a fuel / air mixing chamber 12 is provided in the skid beam 2, and a porous panel 13 is provided on the upper surface of the skid beam 2. Then, a mixture of fuel and air is ejected through the panel 13 to form a combustion flame. Fuel and air are supplied to the mixing chamber 12 through the fuel pipe 15 and the air supply pipe 16, and the combustion flames mixed and ejected from the porous panel 13 become uniform short flames 17. Details of the mixing chamber 12 are shown in FIG.
As shown in the perspective view of (b), the ejection holes 22 are provided in the fuel pipe 15 and the air supply pipe 16 at appropriate intervals, and
Fuel gas and air are spouted from them as shown by the arrows to mix them.

The porous panel 13 may be made of metal or ceramics depending on the heating temperature and other conditions. In this example, the mixing chamber 12 and the porous panel 13 are provided on both sides of the rider 8. If necessary, the surface of the porous panel 13 may be covered with a protective plate 14 as a measure for preventing clogging by a falling scale.
Is installed. The protection plate 14 is heated and becomes a radiation plate to heat the material to be heated. The total length of the porous panel 13 is determined by the required heating amount, and the width is set so as to cover the upper surface of the skid beam 2. The thickness is preferably set to about 20 to 50 mm in order to generate a uniform short flame.

According to the second invention method, the part where the skid mark is generated in the material to be heated 1 is heated by the uniform short flame 17 from the porous panel 13 or the skid beam 2
Radiative cooling to is prevented. And, because of its relatively simple structure, it can be applied to any fixed and movable skid beams in heating zones and soaking zones, and can be applied over the entire length if necessary. Therefore, the skid mark disappears or is significantly reduced.

In the third invention method, as shown in the example of FIG. 5 (a), the double pipe 18 is provided inside the skid beam 2, and the double pipe 1
8 introduces fuel into the inner pipe 20 and air into the outer pipe 19,
Fuel is ejected from the ejection holes 22 provided in the double pipe 1
Burn in 8. The flame 21 in the double pipe 18 heats the upper surface of the skid beam 2. In this example,
A double pipe 18 is provided with the rider 8 in between. Double tube 1
8 is shown in detail, as shown in the perspective view of FIG. 5B, the ejection holes 22 are formed in the inner tube 20 at appropriate intervals, and the ejection holes 22 are
The fuel gas ejected from is burned in the outer tube 19.

According to the method of the third aspect of the invention, the portion where the skid mark is generated in the material to be heated 1 is radiatively heated by the upper surface of the skid beam 2 heated by the flame 21 in the double tube 18 or is directed to the skid beam 2. Radiant cooling is prevented. And, because of its relatively simple structure, it can be applied to any fixed and movable skid beams in heating zones and soaking zones, and can be applied over the entire length if necessary. Therefore, the skid mark disappears or is significantly reduced.

Next, the apparatus of the present invention is applied to the continuous heating apparatus illustrated in FIGS. 1 and 2, and as described in the method of the present invention, the burners 5 are opposed to each other. It can also be applied to the one that employs a system in which pairs are alternately switched to combustion and heat storage. The first invention device is shown in FIG. 3, the second invention device is shown in FIG.
The invented device can have the above-described structure illustrated in FIG. 5, and the operation thereof is as described above.

[0024]

【Example】

(Invention Example 1) In a side burner type heating furnace as shown in FIG. 1, width 1000 mm, thickness 240 mm, length 900
A 0 mm steel slab was charged at 20 ° C and heated to 1190 ° C. As shown in FIG. 3, resistance heating elements 9 and 10 made of an alumina carbide refractory having a thickness of 5 mm are arranged on the heating zone and the soaking beam 2 over substantially the entire length of the three skid beams to conduct electricity. The heating kept the surface temperature slightly higher than the average furnace temperature.

After extraction in the heating furnace, descaling was performed, and the surface temperature of the steel sheet after rough rolling was measured with a radiation thermometer. The results are shown in FIG. 6 in comparison with the conventional example. In the conventional example, the resistance heating elements 9 and 10 are not installed on the skid beam in FIG. 3, except that the resistance heating elements 9 and 10 are heated and rough-rolled under the same conditions as the example of the present invention. The three arrows in FIG. 6 indicate the heating zone and the skid beam position in the soaking zone. In the invention example 1, the skid mark improvement margin ΔT was 19 ° C. as compared with the conventional example, and a remarkable effect was recognized.

(Invention Example 2) In a side burner type heating furnace as shown in FIG. 1, the same slab as in Invention Example 1 was heated under the same conditions. For the heating zone and the soaking beam 2 in the soaking zone, a surface combustion burner having a porous panel 13 made of a zirconia-based refractory having a thickness of 30 mm is provided in the shape as shown in FIG. A short flame film was formed on the skid beam surface by COG (coke oven byproduct gas), and the slab surface above the skid beam was heated.

After extracting from the heating furnace, descaling was performed, and the surface temperature of the steel sheet after rough rolling was measured with a radiation thermometer. The results are shown in FIG. 7 in comparison with the conventional example. The conventional example is the present invention example 1.
The same as in. The three points of the arrow in FIG. 7 are the heating zone and the skid beam position in the soaking zone, but in Example 2 of the present invention, the skid mark improvement margin ΔT was 20 ° C. as compared with the conventional example, and a remarkable effect was recognized.

(Invention Example 3) In a side burner type heating furnace as shown in FIG. 1, the same slab as in Invention Example 1 was heated under the same conditions. As shown in FIG. 5, an eccentric double tube 18 made of stainless steel was disposed on the heating zone and the soaking beam 2 in the soaking zone over substantially the entire length of the upper surfaces of the three skid beams. The inner diameter of the outer tube 19 of the double tube 18 is 70
mm, the inner diameter of the inner tube 20 is 40 mm, and the ejection hole 22 of 3 mmφ is 10 mm in the upper portion of the inner tube 20 as shown in FIG.
It was set up on the pitch. Then, combustion air is supplied to the outer pipe 19 and COG gas is supplied to the inner pipe 20, and the COG ejected from the ejection holes 22 is burned to generate a flame in the double pipe 18, and the upper half of the surface of the outer pipe 19 is generated. Was maintained at a temperature slightly higher than the average furnace temperature.

After extraction in the heating furnace, descaling was performed, and the surface temperature of the steel sheet after rough rolling was measured with a radiation thermometer. The results are shown in FIG. 8 in comparison with the conventional example. The conventional example is the present invention example 1.
The same as in. The three arrows in FIG. 8 are the skid beam positions of the heating zone and the soaking zone, but in Invention Example 3, the skid mark improvement margin ΔT was 17 ° C. as compared with the conventional example, and a remarkable effect was recognized.

[0030]

INDUSTRIAL APPLICABILITY According to the present invention, a metal material such as steel is supported by a skid beam in a heating furnace, and a skid beam having a relatively simple structure is used when heating while moving in the furnace by a walking beam method or a pusher method. Since the upper surface of the beam is heated, it can be applied to any desired position of the skid beam over the entire length from the furnace inlet to the outlet, and it is possible to prevent or significantly reduce skid marks. And
Equipment costs and maintenance costs are relatively low, and there is no risk of deteriorating the fuel consumption rate. Therefore, when rolling or heat treating a metal material such as steel, the operation is stabilized and the product quality is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a continuous heating furnace which is a target of the method and apparatus of the present invention.

FIG. 2 is a cross-sectional view showing another example of a continuous heating furnace which is a target of the method and apparatus of the present invention.

FIG. 3 is a partial cross-sectional perspective view showing an example of the first method and apparatus of the present invention.

FIG. 4 is a sectional view showing an example of a second invention method and device of the present invention.

FIG. 5 is a cross-sectional view showing an example of a third invention method and device of the present invention.

FIG. 6 is a graph showing a temperature distribution in the longitudinal direction of the steel sheet in the example.

FIG. 7 is a graph showing a temperature distribution in the steel sheet longitudinal direction in another example.

FIG. 8 is a graph showing a temperature distribution in the steel sheet longitudinal direction in another example.

[Explanation of symbols]

 1 ... Material to be heated 2 ... Skid beam 3 ... Fixed beam column 4 ... Movable beam column 5 ... Partition wall 6 ... Burner 7 ... Cooling water pipe 8 ... Rider 9, 10 ... Resistance heating element 11 ... Electrode 12 ... Mixing chamber 13 ... Porous Quality panel 14 ... Protective plate 15 ... Fuel pipe 16 ... Air supply pipe 17 ... Short flame 18 ... Double pipe 19 ... Outer pipe 20 ... Inner pipe 21 ... Flame 22 ... Ejection hole

Claims (6)

[Claims] 1. A continuous heating method in which a material to be heated is supported and transferred by a skid beam in a heating furnace and is heated by a burner combustion flame while a resistance heating element is provided on the upper surface of the skid beam to electrically heat the material. Characterized continuous heating method. 2. A continuous heating method in which a material to be heated is supported and transferred by a skid beam in a heating furnace and heated by a burner combustion flame while a mixing chamber for fuel and air is provided inside the skid beam, and the skid beam is provided. A continuous heating method characterized in that a mixture of the fuel and air is ejected through a porous panel disposed on the upper surface of the beam to form a combustion flame. 3. A continuous heating method in which a material to be heated is supported and transferred by a skid beam in a heating furnace while being heated by a burner combustion flame, and a double pipe is internally provided in the skid beam, A continuous heating method, characterized in that fuel is introduced into the inner tube, air is introduced into the outer tube, the fuel is ejected from an opening provided in the inner tube, and the fuel is burned in the double tube. 4. A continuous heating device for heating a material to be heated by a burner combustion flame while supporting and transferring the material to be heated by a skid beam in a heating furnace, with a burner provided on the furnace wall, and on both sides of the rider of the skid beam. A continuous heating device characterized in that a plate-shaped resistance heating element is provided so as not to contact the rider. 5. A continuous heating device for heating a material to be heated by a burner combustion flame while supporting and transferring the material to be heated by a skid beam in a heating furnace, with a burner provided on the furnace wall and a porous panel on the upper surface of the skid beam. Is provided, a mixing chamber is provided in the skid beam below the panel, and a fuel introducing pipe and an air introducing pipe are connected to the mixing chamber. 6. A continuous heating device for heating a material to be heated by a burner combustion flame while supporting and transferring the material to be heated by a skid beam in a heating furnace, wherein a burner is provided on the furnace wall and a double pipe is provided inside the skid beam. A continuous heating device, wherein a fuel introducing pipe is connected to an inner pipe of the double pipe and an opening is provided, and an air introducing pipe is connected to an outer pipe of the double pipe.