JPH11343124A - Glass melting vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity and durability of furnace materials by protecting short pass and reducing bubble formation by making protrude the inlet part of a tubular throat, which introduces molten glass into a working vessel through a partition board from a melting vessel, into the melting vessel and providing an aperture on the upper side of it. SOLUTION: A glass melting vessel 1 comprises a melting vessel 2 and a working vessel 3, which are separated with partition boards 4 and 5. The melting vessel 2 and the working vessel 3 are communicated by a communicative hole 14 which is disposed in the bottom parts of the partition boards 4 and 5, and a square or circle tubular throat 15 is inserted to be protruded from the communicative hole 14. The throat 15 has apertures at both ends on the upper side, as an upstream side aperture 16 and a downstream side aperture 17. Glass material 18 fed in the upper part of the melting vessel 2 melts gradually by heating, and is defoamed and allowed to flow into the aperture 16 and to flow out into the working vessel 3. A cross-sectional area (A cm<2> ) of flow passage in the throat is preferably to be in a range of a measure satisfying a relation of 5×10<-3> <=A/B<=5×10<-2> to a flat area (B cm<2> ) of the melting vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a melting apparatus for improving productivity and extending the life of furnace materials.

[0002]

2. Description of the Related Art Conventionally, some glass melting tanks are provided with a partition wall between a melting tank and a work tank (or a riser and a conditioner) as one of methods for improving the melting efficiency of glass. A narrow communication hole called a throat is provided at a lower portion of the partition wall. The throat is severely eroded by high-temperature glass flowing in at a high speed, and it is common practice to cool the partition wall in order to suppress the erosion as much as possible. However, although the erosion of the throat is suppressed by cooling the partition wall, the molten glass in the vicinity of the partition wall is more cooled, and the amount of the molten glass descending along the wall tends to increase.

[0003] The glass raw material is introduced into the upper part of the molten glass in the melting tank and is melted by the upper heater.
When the molten glass containing the unmelted raw material immediately after melting rides on the descending flow near the partition wall, it is sucked directly into the throat,
Melting of the glass is still insufficient and the glass containing bubbles flows out to the work tank. In order to obtain satisfactory quality as a final product,
It was necessary to heat the glass again to a high temperature in the work tank to reduce the viscosity, and to remove bubbles remaining in the glass by Stokes law.

Therefore, conventionally, in order to prevent such insufficiently molten glass from being mixed, for example, the bottom of the throat is positioned above the bottom of the melting tank, and the inlet of the throat is directed toward the melting tank. Protruding (Japanese Patent Laid-Open No. 52
Japanese Patent Application Laid-Open No. H08-133746), or disposing one electrode of an electrode pair provided on the furnace wall opposite to the melting tank on the furnace wall on the throat inlet side. I have.

[0005]

However, in the method described in, for example, JP-A-52-107017, the incorporation of unmelted glass can be prevented, but the equipment is unstable. Although the method described in JP-A-133746 can prevent the generation of the downflow of the furnace wall, there is a problem that the apparatus becomes large and the erosion of the furnace material at the throat inlet is remarkable.

[0006]

Means for Solving the Problems The inventors of the present invention have developed a glass melting apparatus which has a simple structure with only a throat without using any additional equipment other than the throat, and which has both quality, productivity, and efficiency in changing the glass composition. An apparatus is provided.

That is, the present invention relates to a glass melting apparatus for guiding molten glass from a melting tank to a work tank through a pipe-shaped throat which connects the two tanks to a bottom of a partition wall for dividing the melting tank and the work tank. The present invention relates to a glass melting apparatus characterized in that an inlet of the throat protrudes into a melting tank and an opening of the protruded throat is provided above.

It is preferable that the protruding throat is bent upward to provide an opening. Further, it is preferable that the cross-sectional area (Acm ² ) of the flow path of the throat be within a range satisfying the following expression with respect to the plane area (Bcm ² ) of the dissolving tank.

5 × 10 ⁻³ ≦ A / B ≦ 5 × 10 ⁻² Further, it is preferable that the outlet of the throat is projected into the work tank, and the opening of the projected throat is provided above.

[0010]

1A is a schematic side sectional view of a glass melting tank, and FIG. 1B is a schematic top view thereof. The glass melting tank 1 is composed of a melting tank 2 and a work tank 3, both of which are partitioned by partition walls 4, 5, so that conditions such as temperature and atmosphere do not affect each other.
The melting tank 2 is a tank surrounded by refractories such as a front wall 6, a melting tank side wall 7, a melting tank bottom 8, a melting tank partition wall 4, and a ceiling (not shown). The tank is surrounded by the refractory of the tank-side partition wall 5, the work tank side wall 9, the rear wall 10, the work tank bottom 11, and the work tank ceiling 12. In addition, a canal 13 having a structure in which the depth of the tank is shallow is connected to the work tank 3.

The dissolving tank 2 and the working tank 3 are communicated with each other by a communication hole 14 provided at the bottom of the partition walls 4, 5.
A throat 15 in the shape of a square or a round pipe is fitted into and protrudes from the communication hole. The throat 15 has both ends opened upward, and each end is provided with an upstream opening 16 and a downstream opening 17.

Glass raw material 1 put in upper part of melting tank 2
8 is heated by a heater (not shown) at the top or by direct energization and is gradually melted. The melted molten glass 19 circulates in the tank by convection due to the temperature distribution in the tank, and the glass near the walls 4, 6, and 7 having a low temperature causes a downward flow, and the vicinity of the central part of the melting tank. As a result, the molten glass is gradually defoamed while circulating in the tank.

Although the melting immediately after the melting is insufficient, a part of the molten glass containing bubbles descends along the partition wall 4, the front wall 6, and the side wall 7, but the throat 15 is projected from the communication hole 14; Moreover, since the upstream opening 16 of the throat is opened upward, the descending flow does not directly flow into the opening 16, but only the molten glass that has been defoamed flows through the opening 16, and It is discharged to the work tank 3 of the process.

As the material of the throat, any material can be used as long as it is heat-resistant and corrosion-resistant. In particular, molybdenum and platinum-rhodium alloys are preferable because they have excellent corrosion resistance. The cross-sectional shape of the throat is not particularly limited, such as a circular shape and a square shape.However, from the viewpoint of workability and strength of the material, when molybdenum is used, the square shape uses platinum or a rhodium alloy. In this case, a circular shape is preferable. In addition, throat 1
The degree of protrusion of 5 from the communication hole 14 into the melting tank 2 should be such that the downward flow of insufficiently molten glass descending along the partition wall 4 does not directly flow into the throat as described above. It is particularly preferable that the center of the melting tank 2 (the front wall 6
It is preferable to protrude largely to the vicinity of (approximately the center between the partition wall 4 and the partition wall 4), but the present invention is not limited to this.
Further, the throat 15 may be provided above the bottoms 8 and 11, but it is preferable to provide the throat in contact with the bottoms 8 and 11 in consideration of the flow of glass.

Next, a comparison between a case where the tip of the protruded throat is bent and a case where it is not bent will be described for a throat installed in a melting tank. 2 and 3 show the dissolving tank 2
FIG. 2 shows the flow of the descending flow 20 near the partition wall 4, the front wall 6, and the side wall 7 flowing into the throat 15 protruding into the throat 15, and FIG.
Is a throat having a structure in which the front end portion protrudes to the center portion of the dissolving tank 2 and the front end portion is bent so that the opening 16 is directed upward. FIG. The throat has a structure in which the throat is protruded, but its tip end is not bent, and its opening 16 is directed to the side.

When the throat opening 16 is directed upward as shown in FIG. 2, the downward flow 20 flowing down along the partition wall 4, the front wall 6, and the side wall 7 once reaches the bottom 8 of the melting tank. After that, it rises with the upward flow 21, circulates to a high temperature region in the center of the tank, and after the bubbles of the molten glass are exhausted,
From the vicinity of the upper part of the throat, it flows into the throat as shown in FIG. The molten glass that has flowed into the throat flows out of the work tank 3 through the downstream opening 17 connected to the work tank 3.

On the other hand, as shown in FIG. 3, when the throat tip is not bent and the opening is provided on the side, the downward flow 20 flowing down along the partition wall 4, the front wall 6, and the side wall 7 can be obtained. After reaching the bottom 8 of the dissolving tank, a part of the downward flow 20 descending particularly along the front wall 6 flows along the bottom 8 and then flows into the throat through the side opening 16 of the throat. I do. In this case, the molten glass flowing into the throat has not yet been defoamed, and the non-defoamed glass flows into the work tank, which is not preferable. The height of the bent portion is preferably about twice the throat diameter, but is not limited to this.

The dimensions of the cross-section of the throat are
Is the plane area (cross-sectional area when the dissolution tank is cut horizontally) of Bc
and m ^2, if the vertical sectional area of the flow path of the throat 15 was Acm ^2, it is preferable to dimensioned to satisfy the following equation.

If the ratio of 5 × 10 ⁻³ ≦ A / B ≦ 5 × 10 ⁻² A / B is less than 5 × 10 ⁻³ , the speed of the glass flowing in becomes high, and the melting of the upper layer of the melting tank becomes difficult. Insufficient glass is sucked into the throat. In addition, it promotes erosion or affects the convection of the work tank, which is not preferable.
If the A / B ratio is greater than 5 × 10 ^-2 , the throat 15
The molten glass that has flowed into the throat generates a backflow called back current that causes a problem in the throat, so that the flows in the melting tank and the working tank become unstable, and the productivity is lowered, which is not preferable. The range of A / B is from 6 × 10 ^{−3 to} 9 × 10 ^−3.
Is more preferred.

The work tank 3 is an area for lowering the temperature of the glass melted in the melting tank 2 so as not to contain bubbles at a predetermined temperature to clarify the glass into a homogeneous glass. The inflowing glass rises with the upward flow formed in the tank 3, and in the process, the glass is gradually refined, becomes more homogeneous glass, and is transported through the canal 13 to the final forming step. It is.

Next, a comparison between a case where the tip of the throat protrudes into the tank and a case where it is not made will be described with reference to the throat installed in the work tank. 4 and 5 are views showing the throat on the work tub 3 side. FIG. 4 shows that the throat 15 on the work tub side 3 is protruded to substantially the center thereof, the tip thereof is bent upward, and the opening 17 is formed. 5 is directed upward, and FIG.
No. does not allow the tip of the throat to protrude into the work tank.

The throat in the working tank is projected into the tank,
In addition, in the case of FIG. 4 in which the opening 17 is directed upward by bending the tip end thereof, most of the glass flowing out of the throat flows upward as it is, as indicated by the broken line of the flow of the glass flowing out of the throat. After rising as 22, it is cleared and carried to the canal 13. On the other hand, in the case of FIG. 5 in which the throat does not protrude, the molten glass that has flowed into the work tank 3 rises by the upward flow, but there are many portions that generate a downward flow along the work tank partition wall 5 and the rear wall 10, The glass that has flowed into the work tank is divided into an upward flow and a downward flow, and less glass is directly conveyed to the canal 13, and the efficiency is lower than when the throat is protruded and its outlet is bent.

As described above, it is preferable that the throat 15 protrudes into one of the dissolving tank and the working tank, and it is more preferable that both ends of the throat protrude into both the tanks 2 and 3.

[0024]

According to the melting apparatus of the present invention, the back current (backflow) does not occur in the throat, and the base material near the partition wall of the melting tank descends along the wall and flows directly into the throat. This prevents the occurrence of a so-called short path, prevents deterioration of glass quality due to shortage of staying time of the glass substrate in the melting tank, and has the effect of producing homogeneous glass containing no bubbles with high productivity.

[Brief description of the drawings]

FIG. 1A is a side sectional view of a glass melting tank according to an embodiment of the present invention, and FIG. 1B is an upper sectional view thereof.

FIG. 2 is a partial side cross-sectional view of a throat in which a melting tank side entrance is bent.

FIG. 3 is a partial side sectional view of a throat in which a melting tank side entrance is not bent.

FIG. 4 is a partial side sectional view of a throat in which a work tank side outlet is bent.

FIG. 5 is a partial side sectional view of a throat in which a work tank side outlet is not projected.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass melting tank 2 Melting tank 3 Working tank 13 Canal 14 Communication hole 15 Throat 16 Upstream opening 17 Downstream opening 18 Glass raw material 19 Molten glass 20 Downflow 21 Upstream 22 Upstream

Claims (4)

[Claims] 1. A glass melting apparatus for guiding molten glass from a melting tank to a work tank through a pipe-shaped throat communicating the two tanks with a bottom of a partition wall for dividing the throat into the work tank. A glass melting apparatus characterized in that an inlet portion protrudes into a melting tank and an opening of a protruding throat is provided above. 2. The glass melting apparatus according to claim 1, wherein an opening is provided by bending a tip end of the protruded throat upward. 3. The method according to claim 1, wherein the cross-sectional area (Acm ² ) of the throat flow path is within a range satisfying the following expression with respect to the plane area (Bcm ² ) of the melting tank. Glass melting equipment. 5 × 10 ⁻³ ≦ A / B ≦ 5 × 10 ⁻² 4. An outlet portion of the throat is projected into a work tank,
4. The glass melting apparatus according to claim 1, wherein an opening of the protruded throat is provided above.