JPH04131690A - Tunnel furnace - Google Patents

Abstract

PURPOSE:To permit the efficient heating of products to be baked and the prevention of the generation of variabilities in baking by a method wherein combustion gas from both burners positioned so as to be opposed is collided against each other in a furnace to produce ascending hot air from the place of the collision. CONSTITUTION:Burners 19, provided in respective left and right furnace walls 17, 18, are opposed and, therefore, combustion gas from both burners 19 collides against each other energetically under the operating condition of the group of the burners 19 in a piping space between supporting columns 14 or a space below the products to be baked whereby ascending hot air is produced. In this case, the supplying amount of combustion air per hour with respect to a pair of burners 19 is equal to each other and the ratio of bores of the burners 19 is 5:5, for example, whereby the discharging speed of the combustion gas from the burners 19 is equal to each other substantially. Accordingly, the colliding point of combustion gas from both burners 19 is positioned at the center between both furnace walls 17, 18 substantially. The discharging speed of the combustion gas in the burner 19 provided on the left side furnace wall 17 becomes slower while the same in the burner 19, provided on the right side furnace wall 18, becomes faster.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a tunnel furnace with an improved arrangement of burner groups.

(Prior Art) Conventionally, in a tunnel furnace, burner groups were installed alternately on the left and right furnace walls. Therefore, as shown in FIG. 5, the combustion gas discharged from the burner 1 collides with the furnace wall 2 on the opposite side as shown by the arrow, rises along this wall, and travels along the ceiling 3 to the burner 1. It flowed to the upper part of the furnace 92 on the side, and from there it moved downward along the furnace wall 2. In this way, in the conventional tunnel furnace, the hot air flows in a circular manner around the object to be fired 5 placed on the trolley 4, so that the furnace wall 2 is heated more than necessary and the object to be fired is heated.
The disadvantage was that the heating efficiency was poor.

(Problems to be Solved by the Invention) By the way, in the field of so-called double windows, a heating method has been put into practical use in which hot air from a burner collides at the lower part of the furnace to generate an upward flow of hot air from there. If this method is adopted in a tunnel furnace, it will be possible to heat from the center side of the furnace, that is, from the side of the object to be fired, so the furnace wall will not be heated unnecessarily, and an improvement in heating efficiency can be expected.

However, simply causing the combustion gas from the burner to collide at the lower part of the furnace to generate rising hot air will still result in uneven temperature distribution within the furnace, resulting in uneven firing.

Therefore, in this case, by changing the supply amount ratio of combustion air to both opposing burners over time, as is being attempted at the car window, the collision point of the combustion gas discharged from each burner, and the hot air It is also conceivable to try to make the temperature distribution in the furnace uniform by temporally moving the rising point to the left and right.

However, while the above method was effective for car windows, in tunnel furnaces, rising hot air is not generated smoothly when the collision point of combustion gas is moved to the furnace wall, and the temperature distribution inside the furnace is not sufficiently uniform. Consequently, there was a problem in that the occurrence of uneven firing could not be sufficiently prevented.

Therefore, it is an object of the present invention to efficiently heat the object to be fired instead of the furnace wall by colliding the combustion gases from both burners located opposite each other in the furnace and generating rising hot air from this, and also to prevent uneven firing. The objective is to provide a tunnel furnace that can prevent this from occurring.

[Structure of the Invention] (Means for Solving the Problems) The tunnel furnace of the present invention includes burner groups provided on each of the left and right furnace walls so as to face each other to form a plurality of burner pairs,
The collision point of each combustion gas discharged from both burners forming a pair is located below the object to be fired, and the collision point of the combustion gas of each burner pair is located in the width direction of the tunnel furnace along the moving direction of the cart. Its distinctive feature is that it is set to be dispersed.

Moreover, in this case, it is preferable to set the opening ratio of the shelf assembly in the moving direction of the cart so that at least a portion thereof is 30% or less.

(Function) Since the combustion gases discharged from the pair of burners collide below the shelf assembly of the truck, rising hot air rises from there, and the material to be burned on the shelf assembly is efficiently heated. In addition, since the collision points of each combustion gas are set to be distributed in the width direction of the tunnel furnace along the moving direction of the cart, each combustion gas is Even if the point of gas collision, that is, the point of generation of rising hot air, does not move temporally in the width direction of the tunnel furnace, uneven firing will not occur.

By the way, according to research conducted by the present inventors, the reason why an attempt to shift the collision point of combustion gas from the center of the tunnel furnace in the width direction by varying the amount of air supplied to both opposing burners failed. It turns out that this is the in-furnace wind that is unique to tunnel furnaces. That is, in a tunnel furnace, a large amount of air is forced into the furnace in the cooling zone and the firing zone, and this air flows from the cooling zone and the firing zone to the preheating zone side. The speed of the wind flowing toward the preheating zone reaches about 4 to 5 meters per second because the opening ratio of the shelf assembly in the direction of movement of the truck has conventionally been 50% or more. Therefore, of the two opposing burners, the combustion gas discharged from the burner with a smaller air supply amount is
Since its momentum rapidly decreases, it tends to be bent downstream by the wind inside the furnace. Therefore, the collision state of the combustion gas discharged from both burners becomes unstable,
In the end, not enough rising hot air is generated.

In this regard, if the opening ratio of the shelf assembly is set so that at least part of the opening ratio is 30% or less, the force of the wind inside the furnace will be weakened in the combustion gas discharge area, and the combustion gas discharged from both burners will be reduced. This prevents the direction from being excessively bent. For this reason, the combustion gas collides head-on with force, and a sufficient amount of rising hot air is generated more smoothly.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 2 shows the structure inside the furnace as seen from the moving direction of the trolley 11, in which a refractory shelf assembly 12 is constructed on the trolley 11.
On the shelf assembly 12, a product to be fired (not shown) is mounted, housed in, for example, an H-shaped sagger 13.

The structure of the shelf assembly 12 is as follows. A plurality of flat support columns 14 are arranged side by side on the truck 11, and a plurality of columns 14 are formed on one truck 11.

A horizontal support bar 15 is placed on each column of 14 columns, and a plurality of vertical support bars 16 are combined on top of these horizontal support bars 15 in a direction perpendicular thereto. Therefore, according to this shelf assembly 12, the horizontal support bar 15 and the vertical support bar 1
The hot air in the furnace can flow up and down through the combined parts 6, and the hot air can also flow back and forth and left and right (in the moving direction of the cart and in the orthogonal direction thereof) between the respective supports 14. Here, in this embodiment, in particular, one trolley 1
Regarding one row of the plurality of 14 rows of columns constructed on the rack 1, the opening ratio of the shelf assembly in the moving direction of the cart 11 is set to be 30% or less.

On the other hand, as shown in FIG. 2, a plurality of burners 19 are intermittently provided at the bottom of each of the left and right furnace walls 17 and 18 that constitute the tunnel furnace along the moving direction of the truck 11 (for example, when the truck 11 When the length is about 2m, install one at every 1m). These burner 19 groups are located opposite to each of the left and right furnace walls 17 and 18 so as to constitute a plurality of burner 19 pairs, and the combustion gas discharged from these burners is sent to the shelf assembly 1.
2, that is, the orientation axes are aligned so as to collide head-on below the product to be fired. In addition, the left and right furnace walls 17
, 18, the amount of combustion air supplied per hour to the two burners 19 provided in pairs is equal to each other, but the aperture ratio of the openings through which combustion gas is ejected differs depending on the pair of burners 19. That is, as schematically shown in Figure ¥S1,
Regarding the 19 pairs of burners in the first row located on the front side in the figure, the diameter of the burners 19 provided on the furnace wall 17 and the furnace wall 1
The ratio of the diameter of the burner 19 provided in the second row to the diameter of the burner 19 is, for example, 6:4, and the diameter ratio of the burner 19 pair in the second row is 5:
5, and the aperture ratio for the 19 pairs of burners in the third row is 4:6. In this embodiment, each burner pair 19 is set so that the aperture ratio changes repeatedly in the order shown in FIG.

According to the above configuration, since the burners 19 provided on the left and right furnace walls 17 and 18 face each other, when the burner 19 group is in operation, the combustion gas from both the burners 19 flows into the space where the support 14 is arranged, i.e., the space to be fired. It collides head-on with force below the object, generating rising hot air. Here, the amount of combustion air supplied per hour to the two burners 19 forming a pair is equal to each other; for example, for the pair of burners 19 in the second row from the front in FIG. 1, the diameter ratio is 5:5. ,
The discharge speeds of the combustion gases are approximately equal. Therefore, both burners 1
As shown in the figure, the collision point of the combustion gas from No. 9 is on both furnace walls 1.
It is located roughly between 7 and 18. However, for the 19 pairs of burners in the first row from the front in the figure, the aperture ratio is 6:
4, the discharge speed of combustion gas is slower at the burner 19 provided on the left furnace wall 17 and faster at the burner 19 provided on the right furnace wall 18. Therefore, due to the difference in momentum between the two combustion gases, the collision point is closer to the furnace wall 17 as shown in the figure. Regarding the 19 pairs of burners in the third row, the aperture ratio is 4:6, and the combustion gas discharge speed is slower for the left burner 19 and faster for the right burner 19, so both combustion gases Due to the difference in momentum, the collision point becomes closer to the furnace wall 18, as shown in the figure. below,
Throughout the area where 19 pairs of burners are located,
The point of collision of both combustion gases, that is, the point of generation of rising hot air, is at truck 1.
They are positioned so as to be repeatedly shifted in the width direction of the tunnel furnace along the direction of movement of the combustion gas (the collision point of the combustion gas is indicated by an O mark in FIG. 3).

In this way, the combustion gas does not flow along the furnace wall, and the object to be fired is heated by the rising hot air rising from below, which allows the heating of the combustion gas to be absorbed without wasting heating of the furnace wall. This means that it can be effectively used to heat the fired product, so thermal efficiency can be improved. In addition, as mentioned above, since the point where the rising hot air is generated is repeatedly shifted in the width direction of the tunnel furnace, the objects to be fired are heated evenly under the circumstances where the cart 11 sequentially moves inside the furnace. This means that it can be fired evenly.

Further, as mentioned above, there is a situation in which the wind inside the tunnel furnace flows toward the preheating zone side, but in this embodiment, the opening ratio of the shelf assembly 12 in the direction of movement of the cart 11 is 30.
% or less, the force of the wind inside the furnace is weaker than in the past (the conventional opening ratio was about 50% or more). As a result, the combustion gas discharged from each burner 19 is less likely to be bent downstream by the furnace wind, and the combustion gas from both burners 19 forming a pair is , it will definitely cause a head-on collision. Thereby, the collision points of the combustion gas, that is, the generation points of the rising hot air, can be stably dispersed over a wide range in the width direction of the furnace, contributing to uniform heating of the object to be fired.

In the above embodiment, the amount of combustion air supplied per hour to the two burners 19 in the pair is equal to each other, and the aperture ratios of the two burners 19 are made different to create a difference in combustion gas velocity, thereby reducing the collision point. is distributed in the width direction inside the furnace. According to this, a sufficient amount of combustion gas on the low-velocity side is ensured, so even if the wind in the furnace is strong, it is hardly affected by it, and this is most preferable for stably generating rising hot air.

However, as in the above embodiment, if the opening ratio of the shelf assemblies is set to be at least 30% in the moving direction of the trolley, the force of the wind inside the furnace in the combustion gas discharge area can be reduced to the conventional level. Since the collision points of combustion gas can be dispersed in the width direction of the furnace, the ratio of the amount of combustion air supplied to the two opposing burners can be changed, making it more stable than before. It can generate hot air rising to the top.

Furthermore, the arrangement of the collision points of combustion gas, that is, the points of generation of rising hot air, is not limited to that shown in FIG. 3, but may be arranged in a zigzag pattern as shown in FIG. It is preferable to use an embodiment in which uniform heating of the object to be fired is possible.

[Effects of the Invention] As described above, according to the present invention, the object to be fired is heated by the rising hot air rising from the lower part of the furnace, which is more effective than the conventional tunnel furnace in which the hot air flows along the furnace wall. Thermal efficiency can be improved, and since the points at which the rising hot air is generated are dispersed in the width direction of the furnace, the object to be fired can be heated uniformly. Furthermore, when the opening ratio of the shelf assemblies is set so that at least part of the opening ratio is 30% or less in the moving direction of the cart, the momentum of the in-furnace wind in the combustion gas discharge area can be suppressed, and the generation point of the rising hot air can be suppressed. can be more stably dispersed in the width direction of the furnace, which has an excellent effect of contributing to more uniform heating of the object to be fired.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention, FIG. 1 is a partially cutaway perspective view of a tunnel furnace, FIG. 2 is a vertical sectional view of the tunnel furnace, and FIG. 3 is a combustion gas FIG. FIG. 4 is a view corresponding to FIG. 3 showing a different embodiment of the present invention, and FIG. 5 is a longitudinal sectional view showing a conventional tunnel furnace. In the drawing, 11 is a truck, 12 is a shelf assembly, 14 is a column, 17.
18 is a furnace wall, and 19 is a burner.

Claims (1)

[Claims] 1. A trolley carrying a refractory shelf assembly for placing objects to be fired passes through the furnace, and combustion gas is spouted into the furnace from a group of burners provided on the furnace wall. In the burner group, the burner groups are provided on the left and right furnace walls to face each other to form a plurality of burner pairs, and the collision point of each combustion gas discharged from the pair of burners is at the point of collision of the combustion gases discharged from the burners of the pair. 1. A tunnel furnace, characterized in that the tunnel furnace is located at a lower position and is set so that collision points of combustion gas of each pair of burners are distributed in the width direction of the tunnel furnace along the moving direction of the truck. 2. The tunnel furnace according to claim 1, wherein at least a portion of the shelf assembly has an opening ratio of 30% or less in the moving direction of the truck.