JPH0226926Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a billet heating furnace used in rolling mills of steel mills and the like.

As shown in FIG. 1, a conventional billet heating furnace has a furnace body composed of a hearth 1, side walls 2, and a furnace ceiling wall 3.
It also has a movable support pipe 4 penetrating the hearth 1, a fixed support pipe 5 installed upright on the hearth 1, an upper side burner 6 and a lower side burner 7 installed horizontally on the side wall 2, etc. There is.
Note that 8 is a slab which is a steel piece to be heated, 9 is a pass line of the slab 8, and 10 is a center line in the furnace width direction.

Figure 2 shows the temperature distribution between the furnace ceiling wall 3 and the surface of the slab 8, where a ₁ , b ₁ and c ₁ are A in Figure 1.
In the temperature curves of sections A, B, and C, the angle θ of the upper side burner ₆ with respect to the horizontal line in _FIG .
Then, in the C part, it becomes as shown by the curve _c1 . Note that the vertical axis in FIG. 2 represents temperature, with upward arrows indicating high temperatures and downward arrows indicating low temperatures.

That is, in the conventional billet heating furnace shown in FIG. 1, the upper side burner 6 is installed horizontally, so the combustion gas easily flows toward the furnace ceiling wall 3, and the temperature distribution is as shown in FIG. As shown by the curves a ₁ , b ₁ , and c ₁ , the temperature on the ceiling side increases as the distance from the burner 6 increases.

In Figure 3, the horizontal axis shows the furnace time (minutes) of the slab, and the vertical axis shows the temperature (°C), where the curve d shows the temperature on the furnace wall side, and the curve e shows the temperature on the upper side of the slab. The curve f shows the calculated value of the slab surface temperature when using the above-mentioned slab upper side temperature (see curve e), and the curve g shows the slab surface temperature calculation when using the above-mentioned furnace wall side temperature (see curve d). It shows the value. Note that the X mark in the figure is the actual measured value of the slab surface temperature. In other words, as can be seen from Figure 3, from the actual heating curve, the temperature on the upper side of the slab is more closely related to the slab surface temperature than the temperature on the furnace wall side, so the heat transfer to the slab is It is thought that this may be improved by increasing the temperature on the upper side of the slab. Therefore, in the conventional method shown in Figure 1, the temperature on the wall side increases and the wall loss increases.
Furthermore, it is considered that heat transfer to the slab 8 is insufficient.

This invention improves thermal efficiency by improving heat transfer to the slab, and lowers the temperature of the furnace ceiling wall to reduce wall loss from the ceiling, thereby saving energy and downsizing the furnace. It is an object of the present invention to provide a steel billet heating furnace which can reduce the heat receiving temperature of each part of the furnace body and extend the life of the furnace body.

For this reason, the configuration of the present invention is such that the side burner installed above the pass line of the steel billet is attached to the furnace wall with a downward slope at an angle that prevents combustion gas from directly hitting the surface of the steel billet. It is characterized by the presence of

An embodiment of the present invention will be described below with reference to FIG.

FIG. 4 shows an embodiment of the present invention, and is shown enlarged to correspond to FIG. 1, with some parts omitted. In FIG. 4, the upper side burner 11 is located above the pass line 9 of the slab 8 and is attached to the side wall 2 so that the center line 12 of the burner 11 is inclined downward at an angle θ with respect to the horizontal line 13. It is being In determining this angle θ, in order to prevent local overheating of the slab, the angle is determined so that the combustion gas does not directly hit the surface (upper surface) of the slab 8. That is, 0<θ<15° is preferable.

In the slab heating furnace configured as shown in FIG. 4, the upper side burner 11 is inclined downward by an angle θ, so that the combustion gas first flows toward the surface of the slab 8, and finally arrow 1
4, it flows toward the furnace ceiling wall 3. Therefore, heat transfer to the slab 8 involves radiation from the furnace wall and radiation from the gas, but as explained in FIG. 3, the temperature on the top surface of the slab is lower than the temperature on the furnace wall, that is,
Since the slab surface temperature is in good agreement with the calculation results relative to the gas temperature, it is possible to increase the slab surface temperature by increasing the temperature on the upper surface of the slab, thereby improving heat transfer to the slab 8. can. This is expressed graphically in the diagram on the right side of FIG. 2 where θ>0. In other words, the curve in Figure 2
a ₂ , b ₂ , c ₂ are parts A, B, and C in Figure 4, respectively.
It shows the temperature distribution of the area. That is, when the upper side burner 11 is tilted by the angle θ and directed downward toward the slab surface side, the maximum value of the gas temperature approaches the slab surface side. Further, the temperature of the furnace ceiling wall 3 becomes lower as the temperature increases, and the wall loss decreases. By tilting the upper side burner 11 downward by an appropriate angle θ in this manner, heat transfer to the slab 8 and furnace wall loss can be reduced. Incidentally, if the burner 11 is tilted too much, the combustion gas will directly hit the slab 8, causing local heating, resulting in uneven temperature distribution of the slab 8, which is not preferable.

As mentioned above, in the present invention, the side burner above the pass line of the steel billet is installed on the furnace wall at an angle that prevents combustion gas from directly hitting the slab surface, which improves the heat conductivity of the steel billet. In addition to reducing the furnace time and saving energy, it also lowers the temperature on the furnace ceiling wall side and allows the use of low-grade refractory materials, making it economical and making the furnace wall refractory. It is possible to extend the lifespan of objects. Therefore, it becomes highly capable and productivity improves, and moreover,
The effects of the present invention are extremely large, as the furnace length can be shortened, the installation space can be reduced, and the equipment can be made more compact.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional front view showing an example of a conventional billet heating furnace, Figure 2 is an explanatory diagram showing the temperature distribution between the furnace ceiling wall and the slab surface, and Figure 3 is a diagram showing the relationship between furnace time and temperature. An explanatory diagram showing the relationship, FIG. 4 is a sectional front view showing an embodiment of the present invention. 2...Side wall, 3...Furnace ceiling wall, 8...Slab,
9... Pass line, 10... Center line in the furnace width direction,
DESCRIPTION OF SYMBOLS 11... Upper side burner, 12... Center line of upper side burner, 13... Horizontal line, 14... Arrow of combustion gas flow, θ... Inclination angle.

Claims (1)

[Scope of utility model registration request] A steel billet, characterized in that a side burner provided above the pass line of the steel billet is attached to a furnace wall with a downward slope at an angle that prevents combustion gas from directly hitting the surface of the steel billet. heating furnace.