JP2000128548A - Glass melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass melting furnace capable of producing glass having higher quality by removing the fine bubbles included in molten glass. SOLUTION: A clarifying vessel 3 of the furnace successively provided with a raw material melting vessel 2, a clarifying vessel 3 and a homogenizing vessel 4 in the flow direction of the molten glass 7 is a hermetic structure formed of platinum or platinum alloy in the clarifying vessel 3. The inside of the vessel is formed to a rectangular parallelepiped shape and the ratio of the depth and width of the parallelepiped is 1:1.2 to 20, the ratio of the depth and the length is 1:5 to 30 and the ratio of the depth and the volume (the width × the length ×the depth) is >=1:6. In addition, a gas vent pipe 15 for removing the gas in the vessel is erected in a ceiling section 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a glass melting furnace suitable for melting high quality glass used for optical parts and the like.

[0002]

2. Description of the Related Art As is well known, a glass melting furnace used for melting high-quality glass such as optical glass includes a raw material melting tank for melting raw materials and a fining device for removing bubbles and foreign substances contained in the molten glass. A tank and a homogenizing tank for homogenizing the heterogeneous glass are connected in series, and in some cases, a plurality of fining tanks and homogenizing tanks are provided so that continuous melting of the glass can be performed. In order to melt high quality glass, it is important to remove bubbles and foreign matter and to homogenize the glass.In general, the fining tank and the homogenization tank are made of platinum or a platinum alloy, which is a very stable material made of heat-resistant metal. ing. For this reason, in a portion that comes into contact with platinum or a platinum alloy, an inhomogeneous portion or a bubble is less likely to be generated in the molten glass. Further, regarding the homogenization tank, the size of the tank and the shape of the blades of the stirrer for homogenizing the molten glass are changed so that the quality required for the product is ensured.

On the other hand, removal of bubbles, that is, degassing and defoaming, is described, for example, in JP-B-43-128.
No. 85, or Japanese Patent Application Laid-Open No.
JP-A-135917 and JP-A-51-135918, a bubble-out stirring tank is provided in series in front of a refining tank so that the dissolved gas in the molten glass forms large bubbles by stirring in the bubble-out stirring tank. A technique of defoaming by sending it to a refining tank and allowing it to stand still is disclosed. In such defoaming in the agitating tank and the refining tank, when trying to defoam smaller fine bubbles in the refining tank, the tank is set so as to prolong the time that the molten glass stays in the refining tank. Must be increased in size. If the size of the refining tank is increased to meet this requirement, the amount of platinum used will increase, and the finer the bubbles to be removed, the higher the cost of the furnace will be. I will.

Recently, with the remarkable progress of electronic components and information devices, glass used for them has been
Finer bubbles and foreign matters, which have not been regarded as a problem in the past, have become a problem, and a furnace capable of removing these fine bubbles and foreign matters has been required.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to reduce the fine particles contained in the molten glass without significantly increasing the furnace cost. An object of the present invention is to provide a glass melting furnace capable of removing bubbles and obtaining higher quality glass.

[0006]

The glass melting furnace according to the present invention is a glass melting furnace comprising a raw material melting tank, a fining tank, and a homogenizing tank connected in the flow direction of the molten glass.
It is formed in the shape of a rectangular parallelepiped, and the ratio of the depth to the width of the rectangular parallelepiped is 1: 1.2 to 20, the ratio of the depth to the length is 1: 5 to 30,
The ratio of depth to volume (width × length × depth) is 1: 6 or more. Further, in the fining tank, the glass inlet and the glass outlet are separated and opposed in the longitudinal direction. The glass inlet is provided at a position not more than 25% of the length from one end on the upstream side in the longitudinal direction, and the glass outlet is provided at a position not less than 75% of the length from the one end. In addition, the fining tank is characterized by being formed of platinum or a platinum alloy, and furthermore, the fining tank has a closed structure and The tank is provided with a degassing part for degassing the gas inside the tank, and furthermore, the fining tank is provided with a partition plate having a large number of holes formed inside the tank. It is assumed that.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment will be described with reference to FIGS. 1 is a sectional view, FIG. 2 is a plan view,
FIG. 3 is a perspective view of the fining tank, and FIG. 4 is a perspective view showing a modification of the fining tank.

In FIG. 1 to FIG.
Is configured such that the raw material melting tank 2, the fining tank 3, and the homogenizing tank 4 are connected in the lateral direction along the flow direction of the molten glass 7 by the glass flow pipes 5, 6, respectively. .
Further, the glass melting furnace 1 is a furnace that employs an electric heating method in which, for example, an electric resistance heater and a control unit (not shown) are provided, and the heating amount of the electric resistance heater is controlled by the control unit to adjust the temperature of each part of the furnace. is there. Then, the molten glass 7 obtained by melting the raw material glass in the raw material melting tank 2 is subjected to fining and homogenization, and then from a glass outflow nozzle 8 provided in the homogenization tank 4 to a molding device (not shown). It is continuously fed and formed into the required glass product.

The raw material melting tank 2 has a substantially square shape made of, for example, a corrosion-resistant heat-resistant material such as platinum or a platinum alloy. One end of the flow pipe 5 communicates with the lower part in the tank, and is attached so as to be inclined upward in the downstream direction. Further, since the raw material glass having a relatively low temperature is charged into the raw material melting tank 2, the raw glass having a higher specific gravity than the molten glass 7 sinks to the bottom of the tank and receives a thermal shock. For this purpose, the thickness of the tank bottom is increased, the radius of the corner is increased, and the opening 9 is provided with a flange. In the raw material melting tank 2, the melting of the raw glass and the melting of the molten glass 7 are performed.
Removal of large bubbles inside is performed. The raw material glass to be charged into the raw material melting tank 2 is preliminarily melted in a separate furnace in a glass melting furnace 1 for melting the molten glass 7 and the like.
Rough melt cullet which is vitrified so as to remove components having reactivity with the constituent material is used.

The fining tank 3 has a structure in which the inside of the tank is sealed, and is made of, for example, a corrosion-resistant heat-resistant material such as platinum or a platinum alloy. in flat substantially rectangular parallelepiped shape having a direction, the ratio of the rectangular depth _{d 1} and width _{w 1} is 1: 1.2 to 20,
The ratio of the depth d ₁ to the length l ₁ is 1: 5 to 30, and the ratio of the depth d ₁ to the volume V ₁ (V ₁ = width w ₁ × length l ₁ × depth d ₁ ) is 1: 6. It is formed as described above and is installed horizontally. Furthermore, one end side wall 10 which is the upstream side in the longitudinal direction of the refining tank 3
A glass inlet 11 is formed in the center portion, and the other end of the glass flow pipe 5 is attached to the glass inlet 11 so as to communicate with the glass inlet 11. A glass outlet 13 is provided at the center of the side wall 12 at the other end, which is the downstream side in the longitudinal direction.
The glass outlet 13 is attached to the glass outlet 13 so that one end thereof communicates with the glass flow tube 6 so as to be horizontal. Side walls 10 and 12 opposed in this manner
By providing the glass inflow port 11 and the glass outflow port 13, the molten glass 7 flows in the tank without making a short path.

Further, a gas vent pipe 15 is provided upright on the ceiling 14 of the fining tank 3 so as to communicate with the upper part of the tank. In the refining tank 3, the molten glass 7 flowing from the raw material melting tank 2 is kept in a molten state at a temperature of about 1400 ° C. which is a temperature within a stable upper limit temperature of a tank forming material, for example, platinum, and the inside of the tank is downstream. The dissolved gas in the molten glass 7 floats as fine bubbles while flowing into the space, and is discharged from the surface of the molten glass to the space above the tank, and then discharged from the gas vent pipe 15 to the outside of the tank.

The cuboid shape of the fining tank 3 is set to a depth d ₁
The width w ₁ , the length l ₁ , and the volume are set so as to have the above-mentioned ratios based on the following reasons. That is, when the depth w is ₁ and the width w ₁ is smaller than 1.2 or the length l ₁ is smaller than 5, the fining tank 3
The ratio of the depth d ₁ to the glass volume is increased in the inner, because opportunities dissolved gas in the molten glass 7 is discharged to the outside floats as bubbles is reduced. The width _{w 1} of 20
If it becomes larger, the stagnation portion of the molten glass 7 increases, and an expensive furnace material such as platinum, which does not contribute to enhancing the defoaming effect and reducing the fine bubbles in the molten glass 7, is unnecessarily used. This is because the molten glass 7 in the stagnation portion is further deteriorated, thereby generating an inhomogeneous glass.

Further, it becomes too slender is refiner 3 the length l ₁ is larger than 30, because the thermal efficiency becomes too large surface area compared to the volume is significantly deteriorated. Further, when the depth d ₁ is 1, the volume V ₁ of the tank is set to 6 or more, so that fine bubbles in the molten glass 7 float, and the opportunity to reach the molten glass surface is increased, and the molten glass is temporarily melted. The foam that has reached the glass surface is released from the molten glass surface into the space above the tank without being caught in the molten glass 7 again.

The homogenizing tank 4 is made of, for example, a corrosion-resistant heat-resistant material such as platinum or a platinum alloy, and is agitated by a drive source (not shown) in an upright cylindrical container 16 having an opening at the top. A stirring device 17 is provided. The stirring device 17 is provided with a stirring member 19 at a lower end of a rotating shaft 18 provided vertically in the container 16. The container 16 also has a glass flow path tube 6
The other end of the glass outflow nozzle 8 is also connected to the bottom of the container 16 so as to communicate with the inside of the container 16.
Is attached. Then, the molten glass 7 from which fine bubbles which have flowed into the homogenization tank 4 from the fining tank 3 via the glass flow path tube 6 has been removed is stirred in the container 16 by the stirring device 17 and homogenized. Thereafter, the homogenized molten glass 7 is continuously sent out from a glass outflow nozzle 8 to a forming device or the like.

With the above configuration,
The molten glass 7 that has been melted and flowed out of the raw material melting tank 2 has fine bubbles contained therein removed, and is homogenized to become high-quality glass. Furnace equipment required for this, particularly the refining tank 3, The shape is rational, the furnace material is not used unnecessarily, and the furnace cost is not increased.

In the above embodiment, the fining tank 3
In addition, the glass inlet 11 and the glass outlet 13 are provided on the side walls 10 and 12 facing each other in the longitudinal direction. However, the present invention is not limited to this. The same effect as described above can be obtained.

That is, the inside of the fining tank 21 is sealed.
Corrosion and heat resistant materials such as platinum and platinum alloy
And the inside shape of the tank is molten glass.
Flat rectangular parallelepiped shape having a longitudinal direction in the flow direction
And the cuboid has a depth of d₂And width w₂Is 1: 1.2-
20, depth d₂And length l₂Is 1: 5 to 30, depth d
₂And volume V₂(V₂= Width w₂X length l₂X depth d₂)of
With a ratio of 1: 6 or more, it is installed horizontally
You. Furthermore, one side 2 parallel to the longitudinal direction of the refining tank 21
Length l from upstream side of 2₂Position 25% or less of_in
Is formed with a glass inlet, and this glass inflow
The mouth is attached so that the other end of the glass channel tube 5 communicates with the mouth.
Have been killed. The other side 23 parallel to the longitudinal direction
Length l from upstream₂Position 75% or more of_outTo
Has a glass outlet 13 formed therein.
At the outlet 13, a piece of glass flow tube 6 is
It is attached so that the ends communicate. In addition, clarification tank
The cuboid shape of 21 is changed to the depth d₂Width w based on₂And long
Sa₂, Volume V₂Are set to have the above ratios, respectively.
This is based on the same reason as in the first embodiment.
It is.

Next, a second embodiment will be described with reference to FIGS. FIG. 5 is a cross-sectional view, and FIG. 6 is a perspective view of a fining tank partially cut away. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The configuration of the present embodiment that is different from the first embodiment will be described.

5 and 6, a glass melting furnace 31 is used.
The raw material dissolving tank 2, the fining tank 32, and the homogenizing tank 4
The glass flow pipes 5 and 6 are configured so as to be connected in the horizontal direction along the flow direction of the molten glass 7. The glass melting furnace 31 is a furnace that employs an electric heating method in which, for example, an electric resistance heater and a control unit (not shown) are provided, and the heating amount of the electric resistance heater is controlled by the control unit to adjust the temperature of each part of the furnace. is there. Then, the molten glass 7 obtained by melting the raw material glass in the raw material melting tank 2 is subjected to fining and homogenization, and then from a glass outflow nozzle 8 provided in the homogenization tank 4 to a molding device (not shown). It is continuously fed and formed into the required glass product.

The refining tank 32 has a closed structure inside the tank, and is made of a corrosion-resistant heat-resistant material such as platinum or a platinum alloy. The rectangular parallelepiped has a ratio of a depth d to a width w of 1: 1.2 to 20, a ratio of a depth d to a length l of 1: 5 to 30, a depth d and a volume V (V = Width w x length l
× a depth d) ratio of 1: 6 or more,
It has a depth of, for example, 15 cm, a width of 20 cm, a length of 120 cm and is installed horizontally. Further clarification tank 3
A glass inflow port 11 is formed at the center of the side wall 10 at one end on the upstream side in the longitudinal direction of 2, and the glass inflow port 11 is attached so that the other end of the glass flow path tube 5 communicates with the glass inflow port 11. Have been. A glass outlet (not shown) is formed at the center of the side wall 12 at the other end, which is the downstream side in the longitudinal direction. One end of the glass outlet is formed at the glass outlet so that the glass flow path tube 6 becomes horizontal. It is attached to communicate.

Further, between the side walls 22, 23 parallel to the longitudinal direction of the fining tank 32, an upstream area 33,
Two partition plates 3 formed so that a large number of holes 36 partitioning into three regions of a middle flow region 34 and a downstream region 35 penetrate therethrough.
7 are provided so as to be orthogonal to the flow. Further, the glass flow gaps 39, 39 are provided between the upper end of the partition plate 37 and the inner surface of the ceiling portion 14, and between the lower end and the inner bottom portion 38, which are provided so that both side ends are fixed to the side walls 22, 23.
40 are provided. By providing the partition plate 37 in this way, it is possible to prevent a short path from being formed in the flow of the molten glass 7 in the tank, and to promote homogenization.

Similarly, a gas vent pipe 15 is provided upright on the ceiling 14 of the fining tank 32, and floats as fine bubbles from inside the molten glass 7 while flowing downstream in the tank. Dissolved gas is released from the surface of the molten glass into the space above the tank and discharged outside the tank. As a result, fine bubbles in the molten glass 7 are removed.

The refining tank 32 has a rectangular parallelepiped shape with a depth d.
The width w, the length l, and the volume V are set so as to have the above-described ratios based on the above-mentioned ratio, based on the same reason as in the first embodiment.

With the above configuration,
The molten glass 7 melted and flown out in the raw material melting tank 2 has fine bubbles contained therein removed in the fining tank 32 and homogenized into high-quality glass, similar to the first embodiment described above. The effect of is obtained.

[0026]

As is apparent from the above description, according to the present invention, a high-quality glass in which fine bubbles are removed and homogenized is obtained, and a furnace for obtaining the same is expensive. It has effects such as not being obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a first embodiment of the present invention.

FIG. 2 is a plan view showing the first embodiment of the present invention.

FIG. 3 is a perspective view of a fining tank according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing a modification of the fining tank according to the first embodiment of the present invention.

FIG. 5 is a sectional view showing a second embodiment of the present invention.

FIG. 6 is a perspective view of a fining tank in a second embodiment of the present invention, which is partially cut away.

[Explanation of symbols]

 2 ... raw material melting tank 3, 21, 32 ... fining tank 4 ... homogenization tank 7 ... molten glass 10, 14 ... side wall 11 ... glass inlet 13 ... glass outlet 14 ... ceiling 15 ... degassing pipe 36 ... hole 37 … Partition plate

Claims (5)

[Claims] 1. A glass melting furnace comprising a raw material melting tank, a refining tank, and a homogenizing tank connected in the flow direction of molten glass,
The refining tank is formed in a rectangular parallelepiped shape, and the ratio of the depth to the width of the rectangular parallelepiped is 1: 1.2 to 20, the ratio of the depth to the length is 1: 5 to 30, and the depth and the volume (width × length). (Thickness x depth) is 1: 6 or more. 2. The fining tank is provided such that the glass inlet and the glass outlet are spaced apart from each other in the longitudinal direction and opposed to each other, and the glass inlet is 25 mm in length from one end on the upstream side in the longitudinal direction. The glass melting furnace according to claim 1, wherein the glass outlet is provided at a position of 75% or more of the length from one end of the glass melting outlet. 3. The glass melting furnace according to claim 1, wherein the fining tank is formed of platinum or a platinum alloy. 4. The glass melting furnace according to claim 1, wherein the fining tank has a hermetically sealed structure and is provided with a degassing portion for evacuating the gas inside the tank. 5. The glass melting furnace according to claim 1, wherein the fining tank has a partition plate having a large number of holes formed inside the tank.