JPH03255884A - Continuous calcination furnace - Google Patents

Abstract

PURPOSE:To obtain a stable reduced color of a calcined article by disposing a reducing band where a reducing flame from a burner is prevented from passing through gaps among rollers by a shielding plate located in close vicinity to the rollers opposing to a burner. CONSTITUTION:In a continuous calcination furnace 10, an article 14 to be calcined is calcined upon passing through a calcination band whilst it is carried by a roller 12 from an inlet of a furnace to an outlet of the same, and the article 14 is reduced by a burner 16 in a reducing band located therebehind, and thereafter the article 14 is carried after passing through a heat holding band 21 and cooled into a product. In the reading band, a refractory material- made shielding member 18 is formed over a predetermined range just under and the reducing burner 16 so as to bury a space below the roller 12. Hereby, a reducing flame from the burner 16 is prevented from passing downwardly through spaces among the rollers 12. Accordingly, the flame is prevented from being distributed and a flame state prevented from being disturbed and a flame state prevented from being changed each time the article 14 passes through just under the burner 16. Thus, reducing conditions are kept uniform and stable reduced color is yielded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a continuous firing furnace, and more particularly to a continuous firing furnace characterized by a reduction treatment method.

(Conventional Technique #i) Ceramic tiles and other fired products can be obtained by firing them as they are in various firing furnaces, or by applying a glaze to the surface and firing them.

The color of the fired product thus obtained changes subtly depending on the atmosphere during firing, and especially when fired under a reducing atmosphere, sometimes a rich color or pattern can be obtained.

For this reason, conventionally, when firing a fired product in a firing furnace, a reducing atmosphere is created and a surface reduction treatment is performed simultaneously with the firing.

This reducing atmosphere is generally created by incomplete combustion of the fuel gas by lowering the air-fuel ratio of the burner compared to normal firing, but in reducing firing using such a reducing atmosphere, reducing conditions are maintained evenly. This is extremely difficult to control, as detailed below.

The reduction of the fired product is performed by depriving the fired product of oxygen. When using a fuel gas containing carbon and hydrogen (for example, propane gas), the reducing gas used for reducing the fired product is a mixed gas of Go and H2 gas decomposed by the burner flame. CO gas has a large amount of C in the gas and is relatively stable in a high temperature range of 1200°C or higher, but it is unstable if these conditions are not met, and if there is even a small amount of 02, it becomes 002,
As the temperature decreases, it decomposes into C and CO2 due to carbon deposition reaction, and it no longer functions as a reducing gas.

Therefore, when reducing the fired product by creating a reducing atmosphere in the firing furnace, it is extremely difficult to completely isolate the reducing atmosphere from the external atmosphere such as the atmosphere of the previous and previous processes, and there is no suitable method for reducing the fired product. It is difficult to ensure a reducing atmosphere.

The temperature of the fired product during reduction treatment is also an important factor.
It is extremely difficult to uniformly reduce the fired product in such a reducing atmosphere while adjusting the temperature of the fired product.

As described above, in the conventional reduction treatment method for fired products, it is not possible to stably produce a product having a uniform desired reduced color.

Therefore, the present inventors proposed a continuous firing furnace in which the fired product is placed on rollers arranged in parallel along the conveyance direction and the fired product is moved while being fired by the rotation of the rollers.
By arranging a reduction processing zone in which a reduction chamber is disposed in close proximity to the path of movement of the fired product after the firing zone, and ejecting a reduction flame from the reduction burner and directly spraying it onto the surface of the fired product.

We considered independently reducing the fired product immediately after firing.

In this way, the reduction treatment area can be isolated from the external atmosphere by the reduction flame blown out from the burner at a constant flow rate, making it easy to control and maintain the reduction conditions uniformly, resulting in good reduction. can be done.

(Problem II to be Solved by the Invention) However, in continuous firing as shown in FIG. If the space is large, the flame ejected from the reduction burner 104 toward the fired product 100 will be disturbed or changed every time the fired product 100 passes, and the reduction will not be carried out sufficiently uniformly.

This is because, as shown in the figure, the flame from the burner 104 penetrates through the gap between the burners to the bottom of the roller 102, which reduces the pressure loss in that area, resulting in an imbalance in the discharge flow rate from the burner. This is due to the fact that the flame oscillates or changes its state each time the fired product, such as a tile, passes through the flame, and therefore the reduction conditions change and are not maintained uniformly.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and its gist is to place a baked product on rollers arranged in parallel along the conveyance direction, and to transfer the fired products to the rollers. In a continuous firing furnace that performs firing while moving the fired product by rotation,
It has a reducing chamber disposed close to the conveyance path of the fired object, and the burner directly sprays a reducing flame on the fired object fed from the firing zone to directly reduce the fired object. A shield is positioned close to the roller facing the burner, and a reduction treatment zone is provided so as to prevent the reduction flame from the burner from penetrating the gap between the rollers.

(Function and Effects of the Invention) In the continuous firing furnace of the present invention, a shielding body is located close to the roller facing the reduction burner, and the flame from the burner is caused to cross the gap between the rollers by the action of this shielding body. It is prevented from penetrating through the other side. Therefore, it is possible to suppress state changes such as large flame disturbances each time the fired product such as a tile passes through a part where the reducing flame is ejected, so that the surface of the fired product can be stably reduced under uniform conditions. This makes it possible to obtain a product with a stable and desired reduced color.

(Example) Next, embodiments of the present invention will be described in detail based on the drawings.

In FIGS. 1 and 2, IO is a continuous firing furnace,
A large number of rollers 12 are arranged in parallel at an intermediate position between the upper and lower sides, and the rotation of these rollers 12 continuously conveys and fires the fired product 14, such as tiles.

A reduction burner 16 is disposed facing downward in the reduction treatment zone behind the firing zone of the continuous firing furnace 10. This reducing burner 16 blows out a reducing flame and sprays it directly onto the surface of the fired product 14, thereby reducing the surface independently of firing. Note that 20 is an exhaust duct.

In the continuous firing furnace 10 of this example, a refractory material shield 18 is formed directly below the reducing burner 16 and over a certain range before and after the reducing burner 16 so as to fill the space below the roller 12. is prevented from penetrating downward through the gap between the rollers 12.

In this continuous firing furnace 10, firing is performed while the fired product 14 is conveyed by the rollers 12 from the entrance to the exit of the furnace, specifically when the fired product 14 passes through the firing zone of the furnace. In addition, in a reduction treatment zone behind the firing zone, a reduction treatment using a henna 16 is performed. i.e. / henna 16
The reducing flame ejected from the burner 16 is blown directly onto the surface of the fired product 14 passing directly under the burner (preferably at a distance of 1
5 to 80 layers), the surface is then reduced. This reduction takes place in an extremely short time, and since the part of the reduction process using the reducing flame blown out at a constant flow rate is isolated from the outside atmosphere, the reduction can be carried out well even in the atmosphere. be exposed. After the reduction treatment, the fired products such as tiles are carried out into the atmosphere through a storage zone 21 and left to cool to become a product.

In the continuous firing furnace 10 of this example, a shield 18 is formed below the roller 12, and the flame from the burner 16 is directed below the roller 12 through the gap between the fired products 14 and the gap between the rollers 12. Breaking through is prevented. Therefore, each time the fired product 14 passes directly under the burner 16, the flame is not disturbed or the flame condition changes.In addition, the reduction conditions are maintained uniformly in this reduction treatment zone, and the reduction flame is sufficiently reduced. This contributes to uniform reduction of the fired product 14, resulting in a stable reduced color.

Although the embodiments of the present invention have been described in detail above, the present invention can also be configured in other forms.

For example, it is possible to arrange a plate made of refractory material under the roller 12 and use it as a shield, it is also possible to transport tiles by placing them on a shelf, or it is possible to use the plate as a shielding body. It is also possible to form it as a shield. It is also possible to provide other types of shields, and the form is not particularly limited, as long as it can prevent the flame from penetrating downward through the gap between the rollers 12.

[Brief explanation of drawings]

1 and 2 are a vertical cross-sectional view and a cross-sectional view of a main part of a continuous firing furnace which is an embodiment of the present invention, and FIG. 3 is an explanatory diagram for explaining the problems to be solved by the present invention. It is. lO: Continuous firing furnace 12 Two rollers 14: Baked product 16: Reduction burner 18: Shielding body
20: Exhaust duct 21: Insulating zone Figure 1 0 1 Figure 2

Claims (1)

[Claims] In a continuous firing furnace in which the fired product is placed on rollers arranged in parallel along the conveyance direction and the fired product is moved while being fired by the rotation of these rollers, the furnace is disposed close to the conveyance path of the fired product. A reduction burner is provided, and a reducing flame is directly blown from the burner onto the fired product immediately after firing, which is fed in from the firing zone, for reduction treatment, and a shield is positioned close to a roller facing the burner. . A continuous firing furnace, characterized in that a reduction treatment zone is provided so that the shield prevents the reduction flame from the burner from penetrating the gap between the rollers.