JPS633926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for heating a hot rolled material in a multi-zone continuous heating furnace.

Conventionally, rolling materials are heated in a multi-zone continuous heating furnace with a soaking hearth.When rolling materials directly during operation, when rolling mill rolls are changed, or when a malfunction occurs on the rolling line. When the operation of the heating furnace is temporarily stopped due to such reasons, the rolled material stagnant at the boundary between the heating zone and the soaking zone in the furnace, especially near the nose of the soaking zone, becomes stagnant compared to other parts (heating zone, soaking zone). If the temperature of the rolled material drops significantly during heating, resulting in a significant temperature difference between the rolled materials stagnant in the heating furnace and the operation is restarted, the above-mentioned low-temperature rolled materials may be heated up to the minimum guaranteed rolling temperature. This resulted in wasteful overheating of the rolled material (those stagnant in the heating zone or soaking zone) more than necessary, which led to disadvantages such as wasted fuel and adversely affected quality. Therefore, the present invention has been made to solve the above-mentioned drawbacks, and preferably a plurality of heating burners are newly installed in the sloped ceiling part of the nose part of the soaking zone of the heating furnace near the boundary with the heating zone. is installed in line with the skid position, and when the operation of the heating furnace is temporarily stopped, the rolled material stagnant in the furnace is heated by the burner, and the rolled material stagnant in the furnace is heated by the burner when the rolled material stagnant in the furnace is kept warm or when restarted. The purpose is to average the temperature of the rolled material.

Next, one embodiment of the present invention will be described.

The present invention will be explained using a five-zone multi-zone continuous heating furnace as an example.

Figure 1 is a sectional view showing a heating furnace for carrying out the present invention, where 1 is the heating furnace main body, A and A' are the preheating zone, and A
is the upper preheating zone, A' is the lower preheating zone, B and B' are heating zones, B is the upper heating zone, B' is the lower heating zone, and C is the soaking zone. 2 is the skid, 3 is the flue, 4 is the charging port, 5 is the extraction port, and 6 is located on the furnace wall in front of the upper and lower preheating zones, the upper and lower heating zones, and the soaking zone (right side in Figure 1). It is a burner installed.

In the heating furnace for carrying out the present invention, a plurality of burners 7 are installed in the sloped ceiling part 9 of the soaking zone C near the boundary with the heating zone of the nose part 8 in the width direction of the heating furnace body 1, preferably in skid positions. Arrange them accordingly. When the operation of the heating furnace is temporarily stopped, for example in the heat retention state, by heating the nose section 8 with the burner, the rolled material stagnant in the nose section is heated and the temperature is lower than that of the rolled material in other parts. This prevents the temperature from dropping and equalizes the temperature of the rolling material during stagnation.

For example, slab thickness 220mm x width 1000mm x length 7500
Operations were temporarily suspended while heating a 5-zone furnace for slabs of 1.5 mm in diameter. During this shutdown, fuel consumption was reduced to about 1/2 of that during normal operation, and the fuel was maintained in a heat-retaining state. The stoppage time at this time is approximately 4 hours, and heating is started by restarting the operation and the minimum guaranteed rolling temperature of the rolled material, in this case.
Heating was carried out to 1020°C. In the case of the method of the present invention, the rolled material stagnant at the nose was heated by a burner provided at the nose for heat retention.

During this reheating, the rolled material at the nose section, which had reached the lowest temperature, was heated to ensure the minimum guaranteed rolling temperature of 1020°C.

As a result, the conventional heating method, in which heating extraction is performed without installing a burner in the nose part, and the method of the present invention, in which the rolled material in the nose part is heated with a burner installed in the nose part, and extraction is performed. The results are shown in Figure 2a.
The figure shows the heating results of the conventional method, and FIG. 2b shows the heating results of the present invention method.

As can be seen from Fig. 2, in the case of the conventional method, the rolled material (stagnant at the nose) at a low temperature has a symbol of
Minimum guaranteed rolling temperature (1020℃ in this case)
), the temperature variation with the rolled material stagnant in the other heating zone B and soaking zone C was 80%.
There were times when the temperature was around 50°C, and the average temperature was about 50°C.

On the other hand, it can be seen that in heating according to the method of the present invention, when heating to the minimum guaranteed rolling temperature as in the conventional method, the temperature variation of the rolled material was around 10°C, and efficient heating could be performed.

As explained above, the heating method according to the present invention temporarily stops the operation of the heating furnace, and restarts the operation by actively heating the rolled material at the nose of the heating furnace, where the temperature decreases most significantly in the heat retention state. , it is possible to prevent unnecessary overheating when heating the rolled material to its minimum guaranteed temperature, saving heating fuel, and enabling uniform heating, which has a great effect on improving quality. At the same time, it is possible to obtain great effects such as being able to reduce skid marks that occur in the heating furnace.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the heating furnace of the present invention, and Fig. 2 shows the heating furnace 1 after being restarted from its temporary stop/heat retention state and heating the rolled material to the minimum guaranteed temperature. Fig. 2a shows the temperature of the rolled material after heating by the conventional method, and Fig. 2b shows the temperature of the rolled material after heating according to the present invention. FIG. 3 is a diagram showing the temperature of a rolled material when heating is performed by the method. Explanation of the symbols in the drawings below: 1: Heating furnace body;
2: Skid, 3: Flue, 4: Charging port, 5: Extraction port, 6: Burner, 7: Burner, 8: Soaking zone C
Nose part, 9: Slanted ceiling part of nose part 8, A,
A': Pre-warming zone, B, B': Heating zone, C: Soaking zone.

Claims (1)

[Claims] 1. In a multi-zone continuous heating furnace with a soaking zone hearth, multiple heating burners are installed on the sloped ceiling near the boundary between the nose of the soaking zone and the heating zone, and are used for heat retention or regeneration when heating is stopped. A method for heating a rolled material, characterized by heating the rolled material at a nose portion during heating during operation.