JPS5855248Y2 - Vertical direct-fired heating furnace - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vertical direct-fired heating furnace used in continuous annealing furnaces and the like.

There are two known methods for heating steel strips: direct flame heating methods and radiation tube heating methods.The direct flame heating method has a heating rate of 3 times faster than the radiant tube heating method. It is nearly twice as large, which has a great effect on improving efficiency.

This is because, in a radiant tube heating furnace, the furnace temperature is limited (below 880°C) by the high temperature strength of the radiant tube material.
In a direct-fired heating furnace, the refractory material on the furnace wall is relatively high (
Since the furnace temperature (1250°C) can be obtained, the amount of radiant heat is approximately three times as much.

However, this direct heating method also has the disadvantage of overheating the rolls in the furnace.

In this inspection-type direct-fired heating furnace, the above-mentioned problem is usually solved by cooling the rolls, but in vertical furnaces, when the steel strip is changed direction by the furnace rolls, the copper strip touches the furnace rolls. Because of the surface contact (line contact in horizontal furnaces), simply cooling the rolls cools the steel strip too much, causing various problems.

For this reason, various measures have been taken to protect the rolls in the furnace from the heat in the furnace.

For example, Japanese Patent Application Laid-Open No. 53-9213 proposes a furnace in which a roll chamber is partitioned in the upper part of the furnace body, and rolls are provided in the chamber to isolate the rolls from the combustion gas.

However, with this method, considering flapping when the steel strip runs, poor shape, and threading work, the opening through which the steel strip passes must be made somewhat large to avoid contact with the steel strip. , there is a problem that combustion gases enter the roll chamber from there.

In addition, as another conventional example, as shown in Japanese Patent Application Laid-open No. 53-54106, an apparatus has been proposed in which a roll chamber is provided separately and a water-cooled damper or the like is provided in the communication section between the roll chamber and the heating chamber. .

According to this, although the inflow of combustion gas into the roll chamber can be avoided to some extent, there still remains the risk of damage to the device or breakage of the steel strip due to contact with the steel strip.

In this way, the main purpose of all conventional systems is to prevent the furnace rolls from coming into contact with combustion gas, so
It is necessary to provide a special roll chamber or to install a complicated device in the opening, which has the drawback of complicating the equipment and increasing operation and maintenance costs.

The present invention was proposed as a result of studies to solve these drawbacks.

That is, the basic feature of the present invention is that an in-furnace radiant heat shield is provided below the in-furnace roll, and the maximum value of the angle of the in-furnace heating section from the surface of the in-furnace roll to this shield is 6.
The purpose is to have an opening for steel strip passage of 0° or less,
As a result, the present invention aims to provide a new vertical direct-fired heating furnace that is highly practical and can appropriately protect the rolls in the furnace.

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

First, what is shown in FIG. 1 is a schematic cross-sectional view of a vertical direct-fired heating furnace to which the present invention is applied.

In the figure, 1 is a furnace body, and the inside of this furnace body 1 is divided into two heating chambers 3 and 4 by a partition wall 2.
4 is equipped with a plurality of burners (not shown in FIG. 1).

Additionally, furnace rolls 5 and 6 are provided above the heating chambers 3 and 4, respectively, and an entrance roll 7 and a seal roll 8 are installed below the heating chamber 4. An exit roll 9 is attached.

In such a vertical direct-fired heating furnace, the furnace roll 5,
Most of the heat input to 6 is radiant heat input from the furnace wall heated by the burner, and convective heat transfer from the atmosphere is small.

Therefore, in the present invention, radiant heat shielding plates 10 and 11 are provided below the furnace rolls 5 and 6, respectively, to protect the furnace rolls 5 and 6 from radiant heat.

FIG. 2 shows details of how the radiant heat shielding plates 10 and 11 are installed.

That is, one of the radiant heat shielding plates 10 is installed a little apart from the partition wall 2, and is supported by the furnace walls on the front side and on the opposite side as viewed from the drawing.

The other radiant heat shielding plate 11 is similarly provided at a distance from the furnace wall 1a, and is supported so as to be fixed or movable in the vertical direction by hanging tools 12, 13 and other means.

As an example, a case in which it is movable in the vertical direction will be explained with reference to FIG. 2, and a through hole 14.1 formed in the upper wall of the furnace body.
Rods 17 and 18 are inserted from 5 through the flange 16, and the lower ends of the rods 17 and 18 are connected to anchors 26 and 27.
It is fixed to the radiant heat shielding plate 11 via.

And the upper ends of the rods 17 and 18 are oak) 19.
20 are screwed together, and the radiant heat shielding plate 11 is moved up and down by rotating these nuts 19 and 20 in the left-right direction.

These interceptions are merely examples of the present invention, and any other configuration may be used to move the radiant heat shielding plate 11 up and down.

In addition, in the present invention, the radiant heat shield plate 10.11 may be made of ordinary refractory material, but depending on the case, the radiant heat shield plate may be cooled by air cooling or water cooling to reduce its wall thickness. be.

On the other hand, what is shown at 21 in FIG. 2 is an opening formed by the radiant heat shielding plate 10.11, but if this opening 21 is too large, the radiant heat shielding effect will be impaired.

The amount of radiant heat to the rolls 5.6 in the furnace is proportional to the viewing angle from the roll surface through the opening 21 to the direct-fired heating section, but in this case, the viewing angle is the maximum value of the desired angles from the roll surface. I have to think about it.

That is, the maximum value of the expected angle referred to here is the perpendicular line a extending along the side of the opening 21 side of the radiant heat shielding plate 10, as shown in FIG. It is determined by the angle θ formed by a line connecting the contact point P1 and the lower end corner portion P2 of the radiant heat shielding plate 11 on the opening 21 side.

The problem is to limit the angle of view θ so that the amount of heat input from the opening 21 to the furnace rolls 5 and 6 remains at least to the same extent as that of the furnace rolls of a normal radiant tube heating furnace.

Generally, in the case of a radiant tube type heating furnace, there is no need to install a radiant heat shield plate as described above, so the angle of view can be considered to be a maximum of 180°.

On the other hand, in the case of a direct-fired heating furnace, the amount of radiant heat is about three times that of a radiant tube-type heating furnace, as mentioned above, so in order to reduce this to the same level or less than that of a radiant-tube heating furnace, The angle of view θ may be equal to or less than the angle of view of the radiant tube heating furnace, that is, 60° or less.

This is the reason why the upper limit of the viewing angle θ is limited in the present invention.

In this case, the lower limit of the angle of view θ will be appropriately determined depending on conditions such as the shape and thickness of the steel strip 22.

Since this angle of view θ changes depending on the diameters of the furnace rolls 5 and 6, in this invention, as mentioned above, the radiant heat capacity plate 1
1 in the vertical direction to adjust the angle of view θ).

That is, when the radiant heat shielding plate 11 is moved upward, the angle of view θ becomes larger, and when it is moved downward, the angle of view θ becomes smaller, thereby adjusting the angle of view θ to the optimum angle. It is.

- In the old book design, in order to ensure the outflow of waste gas and prevent heat loss caused by waste gas dissipating near the furnace rolls 5 and 6, which are kept at a lower temperature than the heating part in the furnace, A flue is provided.

In this case, the present invention takes measures as shown in FIG. 3 to protect the radiant heat shield plate 10.11 from the burner flame.

That is, what is shown in FIG. 3a is the radiant heat source shield plate 10.1.
A plurality of burners 24 are provided near the flue 23 provided below the burner 24, and the flame jet emitted from the burner 24 blows the flame inside the furnace in the direction of the flue 23 and away from the radiant heat source shield plate 10.11. This is how it was done.

Also, what is already shown in Figure 3 is the radiant heat source shield plate 10.11.
A space (tied space) 25 is provided between the radiant heat source and the flue 23, thereby weakening the flame flow and reducing the radiant heat source shield plate 10.
．． 11 from the flame is reduced to the level of natural convection heat transfer to prevent overheating.

In this way, the partition wall forming the roll chamber in the furnace will not be constantly exposed to high-temperature gas as in the past, and the refractory used as the radiant heat source shield plate 10. This provides advantages such as improved maintainability.

On the other hand, in the present invention, as shown in Fig. 1, a plurality of flues as described above are provided in the height direction of the furnace wall 1b and the partition wall 2 of the copper strip entry side heating chamber 3, and the flow of combustion waste gas is arbitrarily selected. It is also possible to adjust the relative velocity of the steel strip and waste gas to obtain the desired reaction in the furnace.

This specific embodiment will be explained according to FIG.
) By providing flues in the central portions B and B' of the furnace, the waste gas in the second stage heating chamber 4 can be discharged outside the furnace with less influence on the combustion in the first stage heating chamber 3.

In this case, it goes without saying that it will be more effective if flues are provided at all of A, B, and C.

(ii) By providing the flue at the positions C and A' in the figure, the direction in which the steel strip advances and the direction in which the waste gas flows coincide, and the reaction between the steel strip surface and the waste gas can be reduced.

(iii) Conversely, by providing flues at positions A and C', the flow directions of the steel strip and waste gas are opposite, promoting the reaction between the steel strip surface and the waste gas, and improving convective heat transfer. becomes possible.

Controlling the relative flow velocity between the steel strip surface and the waste gas in this way requires selection of the waste gas composition by adjusting the air-fuel ratio of each heating chamber 3 and 4 separately, and considering the steel strip temperature. This will lead to control of the amount of reaction on the surface, and will bring great industrial benefits.

Further, regarding the configuration of the present invention, in Fig. 1, the partition wall 2 of each heating chamber of the furnace body is the same wall, but there is no problem in providing an independent wall for each heating chamber. .

Further, the effects of the present invention will not be impaired even if the furnace walls surrounding the furnace rolls 10.degree.

As explained above, according to the present invention, an in-furnace radiant heat shield is provided especially in the vicinity of the in-furnace roll, and the in-furnace radiant heat shield is provided with a maximum angle from the surface of the in-furnace roll to the in-furnace heating section. Since the steel strip passage opening has an angle of 60° or less, it is possible to properly protect the furnace rolls from the furnace radiant heat with a simple configuration and without the need for complicated devices in the opening as in the past. It is a device with great practical value that provides various excellent advantages such as the ability to protect the steel strip and prevent contact between the steel strip and the opening, thereby reducing operating and maintenance costs. It is.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of a vertical direct-fired heating furnace to which the present invention is applied, Fig. 2 is an enlarged view of the main part of Fig. 1, and Fig. 3 a and l) are both preferred implementation situations of the present invention. FIG. 2 is a schematic cross-sectional view for explaining. In the figure, 1 is a furnace body, 3 and 4 are heating chambers, 5 and 6 are rolls in the furnace, 10 and 11 are radiant heat source shield plates, 21 is an opening for passing the steel strip, and θ is an angle of view.

Claims (1)

[Scope of utility model registration request] An in-furnace radiant heat shield is provided below the in-furnace roll, and the in-furnace radiant heat shield has an opening for steel strip passage whose maximum angle from the surface of the in-furnace roll to the in-furnace heating section is 60 degrees or less. A vertical direct-fired heating furnace characterized by having.