JPH0135893B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shadow mark reduction device in a metal heating furnace that is installed upstream of a rolling mill and heats metal pieces such as slabs, blooms, and billets to rolling temperature.

A conventional metal piece heating furnace of this type has a structure as shown in FIGS. 1 and 2, for example. That is, in FIGS. 1 and 2, a
is a heated material, b is a heating furnace, c is a heated material support, d is an arrow indicating the traveling direction of the heated material a,
e is an upper burner, f is a lower burner, g is an auxiliary combustion burner to be described later, h is a lower wall of the extraction end, and
In the figure, i is the hearth and j is the port. A material to be heated such as a steel billet shown in FIGS. 1 and 2 is moved in the direction of an arrow d on a support c of the material to be heated in a heating furnace b by an upper burner e and a lower burner f. heated.

However, since the heated material support c is internally cooled by a cooling medium, the portion of the heated material a that is in contact with the support c is cooled by the support c and becomes lower temperature than other portions. Further, since the support c casts a shadow on the heat radiated from the lower burner f and prevents the heat radiated from the lower burner f from reaching the heated material a, the heated material near the support c The portion of material a has a lower temperature than other portions. These low-temperature conditions
Generally, it is called a shadow mark.

Conventionally, an auxiliary combustion burner g has been used for the purpose of reducing this shadow mark. That is, in the heating furnace b in Fig. 1, the auxiliary combustion burner g is attached to the lower wall h of the extraction end of the heating furnace b, and in the heating furnace b in Fig. 2, the auxiliary combustion burner g is attached to the hearth i of the heating furnace b. It is installed. In other words, in both cases, the combustion gas from the auxiliary combustion burner g is simply applied to the shadow mark portion of the material to be heated a to heat the shadow mark portion in an attempt to reduce the shadow mark, resulting in the following problems. .

That is, first, due to the influence of the flow of combustion gas coming out of the upper burner e and the lower burner f, and the flow of gas in the heating furnace b caused by the buoyancy of the high temperature gas in the heating furnace b, the flow of combustion gas coming out of the auxiliary burner g is Since the flow of combustion gas is disturbed, the combustion gas emitted from the auxiliary burner g may not hit the intended shadow mark portion. For this reason, not only is the shadow mark not effectively reduced, but also parts other than the shadow mark are locally overheated. In particular, the smaller the combustion amount of the auxiliary burner g is than the rated capacity, the smaller the momentum of the combustion gas coming out of the auxiliary burner g becomes, the more easily the flow becomes turbulent, and this tendency becomes more pronounced. second, second
In what is shown in the figure, if scale falling from heated material a partially blocks port j of auxiliary combustion burner g, the direction of the combustion gas ejected from port j of auxiliary burner g changes, so that the combustion gas It will no longer hit the desired shadow mark part. For this reason, as described in the first point above, not only the shadow marks are not effectively reduced, but also the parts other than the shadow marks are locally overheated. Thirdly, especially in the case shown in FIG. 2, if the scale falling from the material to be heated a enters the auxiliary burner g and if the port j of the auxiliary burner g is blocked, the combustion of the auxiliary burner g will be interrupted. This will be severely hindered. Fourthly, in both of the configurations shown in FIGS. 1 and 2, the combustion gas from the auxiliary burner g directly serves as a heat source for reducing shadow marks. Therefore, depending on the difference between the size of the shadow mark before being affected by the combustion gas from the auxiliary burner g and the size of the shadow mark allowed when the material to be heated a is extracted from the heating furnace b,
It is necessary to control the combustion amount of the auxiliary burner g so as to control the temperature of the combustion gas near the shadow mark. However, as mentioned in the first and second points above,
If the flow of combustion gas from the auxiliary burner g does not hit the desired shadow mark due to the operating conditions, the combustion amount of the auxiliary burner g, or the influence of the scale, the temperature of the combustion gas near the shadow mark may be controlled. Moreover, parts other than the shadow mark are locally overheated, which not only cannot be controlled effectively but also has an adverse effect.

The present invention has been made in order to solve the above-mentioned problems existing in the prior art. That is, the present invention has been made in order to solve the above-mentioned problems that existed in the prior art. Shadow marks of a metal piece heating furnace that can reduce the shadow marks in the process, the combustion of the auxiliary burner is not inhibited by scale falling from the material to be heated, and the temperature can be controlled reliably. The object of the present invention is to provide a reduction device.

For this reason, the configuration of the present invention provides a metal piece heating furnace equipped with an auxiliary combustion burner for reducing shadow marks attached to at least one of the bottom wall of the extraction end of the metal piece heating furnace and the hearth. an radiation tube having a horizontal portion installed to guide combustion gas from the auxiliary combustion burner and an open end for discharging the gas into the furnace; It is also characterized in that it is located at the lower level and near the horizontal portion of the heated material support.

Embodiments of the present invention will be described below with reference to FIGS. 3 to 7.

3 and 4 show a first embodiment of the present invention, in which 1 is a material to be heated such as a steel billet, 2 is a heating furnace, 3 is a support for the material to be heated, and 4 is the above-mentioned material. An arrow indicates the traveling direction of the heated material 1, 5 is an upper burner, and 6 is a lower burner. That is, the material to be heated 1 is heated in the heating furnace 2 by the upper burner 5 and the lower part 6 while moving on the material to be heated support 3 in the direction of the arrow 4 . In the figure, 7 is the lower wall of the extraction end, 8 is an auxiliary combustion burner for reducing shadow marks, and 9 is the hearth, and up to this point there is no major difference from the one in FIG. 1 described above. Next, reference numeral 10 denotes a radiation tube installed inside the furnace of the auxiliary combustion burner 8, which has a hollow tube shape made of metal or ceramic, and has a horizontal portion 11 and an open end 12.
is located lower than the lower surface of the heated material 1, and as shown in FIG. They are arranged parallel to each other in the vicinity. Therefore, the combustion gas discharged from the auxiliary burner 8 flows through the radiation tube 10 and is discharged from the open end 12 of the radiation tube 10 into the furnace. That is, the heat generated by combustion in the auxiliary burner 8 is transferred to the radiation tube 1.
Since the shadow mark portion of the heated material 1 is heated by the radiated heat from the horizontal portion 11 of the radiation tube 10, the shadow mark is reduced without being affected by the gas flow in the heating furnace 2.

FIG. 5 shows a second embodiment of the present invention.
An auxiliary combustion burner 8 is provided relatively below the extraction end lower wall 7, and the horizontal portion 11 of the radiation tube 10 and the burner 8
This embodiment is only slightly different from the first embodiment in that the space between the spaces is oblique portions, and detailed explanation thereof will be omitted.

FIG. 6 shows a third embodiment of the present invention.
This is a case where an auxiliary combustion burner is provided in the hearth 9. Therefore, the horizontal part 11 of the radiation tube 10 and the burner 8
The space between is a vertical section. In this embodiment as well, since the shadow mark portion of the material to be heated 1 is heated by the radiant heat from the horizontal portion 11 of the radiation tube 10, the shadow mark is reduced without being affected by the gas flow in the heating furnace 2. . Moreover,
Since the radiation tube 10 is attached to the auxiliary combustion burner 8, scale falling from the material to be heated 1 does not enter the port of the auxiliary combustion burner 8.

FIG. 7 shows a fourth embodiment of the present invention.
In particular, an example of a temperature control device is shown. This control device includes a thermocouple 13 as a radiation outer surface temperature detector, a computing unit 14, a temperature indicating controller 17, and the like. That is, the thermocouple 13 is attached to the outer surface of the horizontal portion 11 of the radiation tube 10, and the computing unit 14 is connected to the heating furnace 2 of the material to be heated 1.
This is a calculation unit that takes as input the size of the shadow mark that is allowed during extraction from the irradiation tube and outputs the radiation tube outer surface temperature necessary for reducing the shadow mark.
Furthermore, more accurate control is possible by inputting the dimensions of the material to be heated 1, the time in the furnace, the heating pattern, etc. to the calculator 14.

In the temperature control device configured as shown in FIG. , to the temperature indicating controller 17, where both signals 15
and 16 are compared, and the deviation becomes the output signal 18 of the temperature indicating controller 17.The signal 18 causes the fuel flow rate control valve 19 in the piping to the auxiliary combustion burner 8 and the combustion air flow rate to be adjusted so that the deviation is eliminated. The combustion amount of the auxiliary burner 8 is controlled by adjusting the opening degree of the control valve 20.

Although FIG. 7 shows the auxiliary combustion burner 8 attached to the bottom wall 7 of the extraction end, the temperature can be controlled in the same way for the auxiliary burner 8 attached to the hearth 9 as shown in FIG. can do.

As described above, the present invention provides an auxiliary combustion burner for reducing shadow marks, in which an irradiation tube having a horizontal portion for guiding combustion gas from the burner and an open end for releasing the gas into the furnace is installed inside the furnace of an auxiliary combustion burner for reducing shadow marks. Since the horizontal portion is located below the lower surface of the heated material and near the horizontal portion of the heated material support, the combustion gas emitted from the auxiliary burner flows through the radiation tube. The radiation tube is heated by the radiator, and the shadow mark area is heated by the radiant heat from the horizontal part of the radiation tube, so it is not affected by the flow of gas in the heating furnace or the momentum of the combustion gas coming out of the auxiliary burner. It is possible to reduce shadow marks, and the combustion of the auxiliary burner is not inhibited by scale falling from the material to be heated. Furthermore, since the direct heat source for reducing shadow marks is the radiation tube, and the position of the radiation tube is fixed, it is possible to control the size of the shadow marks by controlling the temperature of the outer surface of the radiation tube. In addition, the effects of the present invention are extremely large, such as the fact that local overheating of the material to be heated by the auxiliary combustion burner does not occur.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view showing one example of a conventional steel billet heating furnace, FIG. 2 is a partially cutaway side view showing another example, and FIG. 3 is a partially cutaway side view showing another example of the conventional steel billet heating furnace. Partially cutaway cross-sectional side view showing the first embodiment;
The figure is a sectional front view taken along cutting line A-A in Fig. 3, Fig. 5 is a partially cutaway sectional side view showing the second embodiment of the present invention, and Fig. 6 is also a third embodiment. FIG. 7, a partially cutaway side view, is an explanatory view showing the fourth embodiment. DESCRIPTION OF SYMBOLS 1... Heated material, 2... Heating furnace, 3... Heated material support, 7... Extraction end lower wall, 8... Assist burner, 9... Hearth, 10... Irradiation tube, 11...
Horizontal part, 12...Open end.

Claims (1)

[Scope of Claims] 1. A metal piece heating furnace equipped with an auxiliary combustion burner for reducing shadow marks attached to at least one of the bottom wall of the extraction end of the metal piece heating furnace and the hearth. a radiation tube having a horizontal portion that guides combustion gas from the auxiliary combustion burner and an open end that discharges the gas into the furnace, and the horizontal portion of the radiation tube is located below the lower surface of the material to be heated. and is located near the horizontal portion of the heated material support,
Shadow mark reduction device for metal piece heating furnace. 2. A calculator that calculates the temperature on the outside surface of the radiation tube necessary for reducing shadow marks by inputting the temperature detector attached to the outside surface of the radiation tube and the allowable size of the shadow mark when the material to be heated is extracted from the heating furnace. Then, the radiation tube outer surface temperature signal from the temperature sensor and the necessary radiation tube outer surface temperature signal output from the calculator are inputted, and the deviation between the two signals is outputted and auxiliary combustion is performed so that the deviation is eliminated. 2. The apparatus according to claim 1, further comprising a temperature control device comprising a temperature indicating controller for controlling the combustion amount of the burner.