JPH11171554A - Furnace material for reduced pressure defoaming device of molten glass and reduced pressure defoaming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a furnace material for a reduced pressure defoaming device for molten glass which is capable of subjecting a large amt. of the molten glass to reduced pressure defoaming treatment and is applicable to a large-sized glass melting furnace forming furnace and a device therefor. SOLUTION: The furnace material of at least the part in direct contact with the molten glass of the flow passage 40 of a reduced pressure defoaming vessel among a riser 16 housed in a reduced pressure casing, the reduced pressure defoaming vessel 14 for executing the molten glass 8 to the reduced pressure defoaming treatment and a downcomer 18 is formed of refractories having a porosity of <=5%. The refractories are preferably electroformed refractories or densely fired refractories.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace material used for a vacuum degassing apparatus for molten glass for removing air bubbles from a continuously supplied molten glass, and to a vacuum degassing apparatus for molten glass using the same.

[0002]

2. Description of the Related Art Conventionally, in order to improve the quality of molded glass products, a vacuum degassing apparatus for removing air bubbles generated in a molten glass before molding the molten glass in a melting furnace by a molding apparatus. Is used. FIG. 5 shows such a conventional vacuum degassing apparatus. The vacuum degassing apparatus 100 shown in FIG. 5 is used for a process in which the molten glass G in the melting tank 112 is degassed under reduced pressure and is continuously supplied to the next processing tank. I have. A decompression degassing tank 104 is horizontally accommodated in a decompression housing 102, and an ascending pipe 106 and a descending pipe 108 vertically attached to both ends thereof are accommodated and arranged.

The rising pipe 106 communicates with the vacuum degassing tank 104, and the molten glass G before defoaming is lifted from the melting tank 112 and introduced into the vacuum degassing tank 104. The downcomer 108 is
The molten glass G after the defoaming process is communicated with the vacuum degassing tank 104.
Is lowered from the vacuum degassing tank 104 and led out to the next processing tank (not shown). In the decompression housing 102, around the decompression degassing tank 104, the rising pipe 106, and the downcoming pipe 108, a heat insulating material 110 such as a heat insulating brick for heat insulating and covering these is provided. The decompression housing 102 is made of metal, for example, stainless steel.
The inside of the vacuum degassing tank 104 provided therein is maintained at a predetermined reduced pressure, for example, at a reduced pressure of 1/20 to 1/3 atm. .

In the conventional vacuum degassing apparatus 100, the molten glass G at a high temperature, for example, at a temperature of 1200 to 1400 ° C.
Therefore, as disclosed in Japanese Unexamined Patent Application Publication No. 2-221129 filed by the present applicant, the vacuum degassing tank 104, the riser 106 and the downcomer 1
08, etc., the part which is in direct contact with the molten glass G,
Usually, it is formed of a circular pipe made of a noble metal such as platinum or a platinum alloy such as platinum rhodium. The present applicant has put a vacuum degassing apparatus into practical use by using a platinum alloy circular tube.

[0005] The reason why these are made of a circular pipe made of a noble metal such as a platinum alloy is that not only the molten glass G has a high temperature but also the noble metal has low reactivity with the molten glass at a high temperature, and the reaction with the molten glass is low. This is because a high-temperature can be secured to some extent without causing inhomogeneity due to the above. In particular, when the vacuum degassing tank 104 is composed of a precious metal circular pipe,
In addition to the above-mentioned reason, the reason is that an electric current is caused to flow through the precious metal circular tube itself to cause self-heating, thereby uniformly heating the molten glass G in the circular tube and keeping the temperature of the molten glass G at a predetermined temperature.

[0006]

When the vacuum degassing tank 104 is made of a noble metal, it is preferable to use a circular tube from the viewpoint of mechanical strength. However, since a noble metal such as platinum is expensive, the thickness is reduced. Since the thickness cannot be increased, the diameter of the circular pipe is limited in terms of both cost and strength, and cannot be so large. The flow rate of the molten glass G that can be defoamed in the vacuum degassing tank 104 is also limited. However, there is a problem that a vacuum degassing apparatus cannot be constructed. Of course, it is conceivable to increase the total length of the tubular vacuum degassing tank 104 to increase its capacity and increase the amount of degassing treatment. However, since there is a problem that the apparatus becomes long and expensive, the decompression degassing tank 104 is used. There is a problem that the defoaming treatment amount (flow rate) of the molten glass G in the apparatus 100 cannot be increased.

[0007] Further, since the molten glass G is obtained by melting and reacting a powdery raw material, it is preferable that the temperature of the melting tank 112 be higher in terms of melting, and that the molten glass G be degassed under reduced pressure. It is preferred that the viscosity be low and therefore the temperature be high. However, the conventional vacuum degassing apparatus 110
It is necessary to use a noble metal alloy for the vacuum degassing tank 104 and the like from the point of high temperature strength, but the noble metal is expensive and the thickness of the circular tube cannot be made too large from the point of cost. When a noble metal is used, the vacuum degassing apparatus 10
The temperature of the molten glass at the entrance of 0 was limited to the above-mentioned predetermined temperature (1200 to 1400 ° C.).

On the other hand, the temperature suitable for forming the defoamed molten glass in the forming machine (forming tank) depends on the forming object, for example, a plate material or a bottle material, but is limited to a predetermined temperature. ing. Therefore, the vacuum degassing tank 104
When a noble metal is used, the temperature of the molten glass G at the inlet of the vacuum degassing apparatus 100 is limited to about 1400 ° C., the flow rate (processing amount) cannot be increased, and the amount of heat brought in by the molten glass G itself is too large. There is no vacuum degassing device 1
There is a problem that the temperature of the molten glass G at the outlet of the vacuum degassing apparatus 100 drops below the temperature required for molding due to the decrease in the temperature of the molten glass G within 00. Therefore, as described above, it is necessary to uniformly heat the molten glass G in the vacuum degassing tank 104, and for this uniform heating, the vacuum degassing tank 104 itself has to be a precious metal circular pipe.
As a result, there is a problem that the processing amount cannot be increased as described above.

In order to overcome the above-mentioned problems, instead of using expensive and costly precious metal materials such as platinum alloys for the vacuum degassing tank 104, the riser pipe 106 and the descender pipe 108, these materials are used. It is conceivable to use a refractory furnace material which is inexpensive and inexpensive as compared with the above. In general, when a refractory furnace material is used in a melting furnace, a foaming phenomenon in which fine bubbles are generated from the surface of the refractory material at the initial stage when the refractory material used as the furnace material comes into direct contact with the molten glass is known.
In these bubbles, since the surface of the refractory in contact with the molten glass is in a reduced state, carbon, carbide and nitride, which are impurities on the surface of the refractory, are combined with oxygen, so that carbon dioxide (CO ₂ ) gas and There are two types: bubbles generated as nitrogen (N ₂ ) gas, and bubbles generated from the surface of the refractory when gas in pores existing in the refractory comes into contact with molten glass.

In general, the pores present in the refractory include open pores (apparent pores) whose pores communicate with the outer surface.
And, there are closed pores in which the pores do not communicate with the outer surface and exist independently, and when a refractory having at least one of such two types of pores is used as a furnace material of the vacuum degassing apparatus 100, In the case of open pores, the gas contained in the pores becomes bubbles at a burst at the initial stage of contact with the molten glass, and thereafter there is little bubbling from the pores, and in the case of closed pores, at the initial stage of contact with the molten glass. Although the gas contained in the pores does not suddenly become bubbles, the closed pores inside the refractory gradually come into contact with the molten glass as the surface is gradually shaved by the erosion of the refractory, so that the inside of the pores gradually increases. It is conceivable that the gas contained in is foamed as bubbles. Therefore, if a refractory furnace material is used in the flow path of the vacuum degassing apparatus 100, bubbles may be generated from the furnace material for a long period of time even after the start of use.

Further, when a refractory furnace material is used for the flow path of the vacuum degassing apparatus, the temperature of the molten glass G is not changed from the conventional vacuum degassing treatment conditions when platinum is used as the furnace material. Also, in order not to raise the temperature to a high temperature and accelerate the erosion of the furnace material, the temperature of the molten glass G is set to about 1200 to 140
It is conceivable to set the temperature to 0 ° C. However, this defoaming treatment temperature, about 1200 to 1400 ° C., is a conventional defoaming treatment step using only a fining agent, that is, bubbles are grown by the fining agent, and the bubbles are raised in the molten glass. The defoaming treatment temperature in the step of defoaming by defoaming on the surface of the molten glass liquid is relatively lower than about 1400 to 1500 ° C. For this reason, in the vacuum degassing system using the refractory furnace material for the molten glass flow path, the erosion rate of the refractory furnace material used for the flow path is low, and the closed pores inside the refractory are exposed to the surface by the erosion. It is conceivable that air bubbles appear and generate little. However, as described above, in the vacuum degassing apparatus using the refractory furnace material in the flow path, the defoaming process is performed at a relatively lower temperature than the defoaming process temperature in the conventional fining process using only the fining agent. Therefore, the viscosity of the molten glass G is higher than in the case of performing the defoaming treatment using a fining agent, the rising speed of the bubbles once generated on the surface of the refractory in the molten glass G is reduced, and the defoaming is performed. There is a problem that it is not possible to dispel the possibility that the operation is not performed sufficiently.

A first object of the present invention is to solve the above-mentioned problems of the prior art, to reduce the cost and cost as compared with expensive noble metal materials such as platinum and to reduce the generation of bubbles from itself.
Even if bubbles are generated, it is also degassed reliably during the degassing process of the molten glass under reduced pressure, so that the molten glass can be degassed reliably and the quality of the glass can be maintained at high quality. An object of the present invention is to provide a furnace material for a vacuum degassing apparatus for molten glass. A second object of the present invention is to provide a low-cost, high-rate, for example, a molten glass having a flow rate of, for example, 15 tons / day or more, which can be defoamed. An object of the present invention is to provide a vacuum degassing apparatus for molten glass which can be used by being disposed in a processing tank and which is more compact than these.

[0013]

Accordingly, the present inventors have conducted intensive studies on refractory furnace materials which can be used in place of precious metal materials such as platinum alloys in a vacuum degassing apparatus for molten glass. As a result, the following findings have been obtained, and the present invention has been achieved.

First, when a furnace material using a refractory is used in a vacuum degassing tank instead of using a noble metal material such as a platinum alloy, the cost is higher than that of a noble metal material regardless of the type of refractory. In addition, a vacuum degassing device capable of processing a large flow of molten glass can be manufactured, and air bubbles generated in the melting furnace can be degassed from the molten glass. In addition, vacuum degassing to reduce the size of the device and improve workability Since the volume of the tank is reduced, the area of the surface of the refractory in contact with the molten glass relative to the flow rate of the molten glass becomes relatively large. Therefore, when the refractory is used as a furnace material, depending on the refractory, the Erosion was fast, and the amount of bubbles generated from closed pores was not negligible. Moreover, the bubbles generated from the pores of such a refractory are not large enough to float inside the molten glass using a fining agent and defoam, so that they cannot float inside the molten glass having a high viscosity. Not
It has been found that the size of the glass as a product is significantly reduced because it remains in the molten glass and is large enough to be visually recognized as compared with bubbles generated by a chemical reaction.

[0015] Therefore, the amount of bubbles generated from the surface of the refractory as a furnace material which comes into direct contact with the molten glass due to the open pores and the closed pores which come into contact with the molten glass due to the erosion of the refractory. As a result of studying the relationship between the amount of generated bubbles and the number of bubbles remaining in the molten glass after degassing under reduced pressure, the porosity of the refractory used as a furnace material for the depressurized defoaming device was set to a predetermined value, that is, 5%. By:
The total amount of bubbles generated from the surface of the refractory and the eroded surface that comes into direct contact with the molten glass is small over a long period, and even if these bubbles are not completely removed, the number of remaining bubbles is acceptable as glass products. And found that it is suitable as a furnace material for vacuum degassing equipment, and that the furnace material can be used to degas large amounts of molten glass. The present inventors have found that they can be used by disposing them in a melting furnace, a melting tank, a forming furnace or a forming processing tank, and have reached the present invention.

That is, a first aspect of the present invention is a furnace material used in at least a portion of a flow path of a vacuum degassing apparatus for defoaming molten glass, which is in direct contact with the molten glass, and has a porosity. An object of the present invention is to provide a furnace material for a vacuum degassing apparatus for molten glass, characterized by using a refractory of 5% or less.

At this time, the refractory preferably has a porosity of 3% or less, and the refractory is preferably an electroformed refractory or a densely fired refractory.
The electroformed refractory is at least one type of electroformed refractory of an alumina-based electroformed refractory, a zirconia-based electroformed refractory, and an alumina-zirconia-silica-based electroformed refractory. Are dense alumina-based refractories, dense zirconia-silica-based refractories, and dense alumina-
It is preferably at least one kind of zirconia-silica-based refractory. Further, it is preferable that the refractory is a material obtained by polishing at least a surface layer of a surface of an electroformed refractory which is cast into a predetermined shape and which is in direct contact with molten glass, and a surface layer of the electroformed refractory is preferably polished. Is
At least 5 mm or more, and this surface layer is at least 5 mm.
mm, the apparent porosity of the electroformed refractory is 1
% Or less is preferably a furnace material for a vacuum degassing apparatus for molten glass.

According to a second aspect of the present invention, there is provided a decompression housing, which is sucked under reduced pressure, and a high-flow rate housing which is housed in the decompression housing and which is constituted by the furnace material for the decompression defoaming apparatus of the first aspect. A vacuum degassing tank having a flow path for flowing the molten glass and a defoaming space, and a vacuum degassing tank for degassing and degassing the molten glass, and the molten glass before the defoaming treatment is communicated with the vacuum degassing tank. And a deriving unit that is connected to the vacuum degassing tank and that derives the degassed molten glass from the vacuum degassing tank. .

Here, the flow path of the vacuum degassing tank preferably has a rectangular cross section. Further, the introduction means and the derivation means are a riser and a downcomer, respectively, and at least one of the riser and the downcomer is
It is preferable to constitute the furnace material, and it may be a tube having a rectangular cross-section flow path, and it is further preferable that the tube is housed in the vacuum housing together with the vacuum degassing tank. The flow rate of the molten glass in the flow path of the vacuum degassing tank is preferably 15 tons / day or more. Further, it is preferable that the vacuum degassing apparatus has a cooling device for cooling the molten glass.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The furnace material for a vacuum degassing apparatus for molten glass according to the present invention is characterized by using a refractory having a porosity of 5% or less. Are voids of 10 mm or less, and shrinkage cavities (v
Oid) does not include a gap having a size exceeding 10 mm. Here, shrinkage cavities are voids formed by volume shrinkage during electroforming refractory casting. Hereinafter, a furnace material for a vacuum degassing apparatus for molten glass and a vacuum degassing apparatus for molten glass using the same according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings. FIG. 1 is a schematic sectional view of one embodiment of a vacuum degassing apparatus for molten glass according to the second aspect of the present invention. FIG. 3 shows the vacuum degassing apparatus for molten glass shown in FIG.
FIG. 2 is a view taken along line II, showing a cross section of the vacuum degassing tank.

As shown in the figure, a vacuum degassing apparatus 10 for molten glass according to a second embodiment of the present invention performs a degassing process on a molten glass G in a melting tank 24, and a next processing tank (not shown). ,
For example, it is used for a process of continuously supplying a plate material forming processing tank such as a float bath or a forming work tank such as a bottle, etc.
And a vacuum degassing tank 14 having a rectangular cross section which is horizontally housed and disposed in the decompression housing 12, and an upper end portion which is vertically housed and disposed in the decompression housing 12, at each of the left and right ends of the vacuum degassing tank 14. And an ascending pipe 16 and a descending pipe 18 to which are attached. Further, the vacuum degassing apparatus 10 of the illustrated example is used.
In this embodiment, a heat insulating material 20 is filled between the decompression housing 14 and the vacuum degassing tank 14, the rising pipe 16 and the downcoming pipe 18, and the vacuum degassing tank 14, the rising pipe 16 and the downcoming pipe 18 are filled.
Are heat-insulated. Further, in the vacuum degassing apparatus 10 for molten glass in the illustrated example, the vacuum housing 12
In the upper part of the downcomer 18, a cooling pipe 22 is provided along the outer periphery of the downcomer 18.

In the illustrated example, the upper part of the riser 16 is housed in the leg 12 a of the decompression housing 12. The lower portion of the riser 16 is provided with the decompression housing 1.
The second projection 12 protrudes from the leg 12 a, is fitted into the open end of the upstream guide duct 26, and is immersed in the molten glass G in the upstream guide duct 26. The upstream guide duct 26 is connected to the melting tank 24. On the other hand, the upper part of the downcomer 18 is housed and arranged in the leg 12 b of the decompression housing 12. The lower portion of the downcomer pipe 18 is provided with the decompression housing 1.
The second projection 12 protrudes from the leg 12b, is fitted into the open end of the downstream guide duct 28, and is immersed in the molten glass G in the downstream guide duct 28. The downstream guide duct 28 communicates with a next processing tank (not shown).

In the illustrated example, the decompression housing 12 is a substantially portal-shaped stainless steel housing having both legs 12a and 12b. The decompression housing 12 accommodates a decompression degassing tank 14, an ascending pipe 16 and a descending pipe 18; It functions as a pressure vessel for maintaining the inside of the vacuum degassing tank 14 under a predetermined pressure reducing condition (described later), and has a suction port 12C at the upper right portion in the drawing for vacuum suctioning the inside to reduce the pressure. The suction port 12C of the decompression housing 12 is connected to a vacuum pump or the like (not shown). Note that the shape and material of the decompression housing 12 are not limited at all, as long as the function is not hindered.

The vacuum degassing tank 14 communicates with the upper end of the riser 16 at the lower left side in FIG. 1 and the downcomer 18 at the lower right side.
The suction ports 14a and 14b for maintaining the inside of the vacuum degassing tank 14 at a predetermined reduced pressure state (set reduced pressure condition) are provided on the upper left and upper right sides of the upper side of the tank. In the vacuum degassing tank 14, the molten glass G introduced from the rising pipe 16 flows toward the right side in the figure and is led out to the downcomer pipe 18. There is provided an upper space 14s for floating air bubbles to break them. Furthermore, in order to stop air bubbles floating in the molten glass G in the vacuum degassing tank 14 to promote foam breaking, and to reduce or prevent the outflow of air bubbles downstream,
Barriers 30a and 30b are provided, a part of which is immersed in the molten glass G and the remainder protrudes into the upper space 14s.

Here, the reduced pressure condition in the reduced pressure degassing tank 14 depends on the conditions such as the viscosity (temperature) of the molten glass G and the like.
/ 20 to 1/3 atmosphere. Further, the level difference H between the molten glass G in the melting tank 24 and the molten glass G in the vacuum degassing tank 14 is determined by the molten glass G according to the set pressure reduction conditions.
The level difference is set so as to prevent bumping and overflow of the substrate from the decompression tank. Therefore, the vacuum degassing tank 1
4 is set to 1/20 to 1/3 atmosphere, the level difference H of the molten glass G between the melting tank 24 and the vacuum degassing tank 14 is set.
Requires about 2.5 to 3.5 m.

As shown in FIG. 3, the vacuum degassing tank 14 has a flow path cross section of a predetermined dimension, preferably a rectangular cross section, and a pipe of a predetermined length, preferably a square tubular pipe (square pipe). And a dense refractory material having a high bulk density, that is, a refractory furnace material having a porosity of 5% or less, preferably 3% or less, which is a furnace material for a vacuum degassing apparatus according to the first aspect of the present invention. Be composed. In the present invention, the cross-sectional shape of the flow path of the vacuum degassing tank 14 is not limited, and may be any shape, such as a rectangle, a circle, an ellipse, and a polygon shown in FIG. However, it is preferable to make it rectangular as shown in FIG. Therefore, in the following, the cross section of the flow channel will be described using a rectangle as a representative example. Here, the porosity is the ratio of the pore volume contained in the refractory to the total volume, and is (1−bulk specific gravity / true specific gravity).
× 100 (%), where the pore volume occupying the inside of the refractory is large, the porosity is high, and the pore volume occupying the inside is small, indicating that the porosity is small. The bulk specific gravity and the true specific gravity are measured according to JIS R2205. Further, the pores here include open pores and closed pores.

Next, a furnace material for a vacuum degassing apparatus according to the first embodiment of the present invention will be described. The furnace material for a vacuum degassing apparatus according to the first aspect of the present invention is also suitably used for the vacuum degassing tank, ascending pipe and descending pipe according to the second aspect of the present invention. The furnace material of the present embodiment is characterized by using a refractory having a porosity of 5% or less. In the present embodiment, the porosity of the refractory used as the furnace material is set to 5% or less, if the porosity of the refractory is 5% or less, the refractory furnace material is supplied to a flow path of a vacuum degassing tank or the like. Even when used, the number of bubbles in the molten glass generated by the gas in the pores of the refractory can be maintained within an allowable range, the corrosion resistance is high, and the life of the flow path, that is, the pressure reduction defoaming device is used. This is because the service life also satisfies the required level.

Hereinafter, the reason why the porosity of the refractory used as the furnace material of the present embodiment is limited to 5% or less will be described in detail. As described above, among the bubbles mixed in the molten glass, those due to the pores of the refractory are caused by open pores,
There are two types that are caused by closed pores. The former occurs almost at the beginning of the decompression and defoaming process, and does not occur as the apparatus operates, whereas the latter gradually occurs during the operation. As described above, bubbles due to closed pores have a larger diameter than bubbles due to a chemical reaction, and are likely to be fatal unless defoamed from the molten glass.

By the way, in the defoaming fining treatment using a usual fining agent or the like, the viscosity of the molten glass is low at a high temperature and easily escapes and defoams. At a low temperature, the erosion is extremely small. Does not matter. For this reason, it has been considered that the amount of generated bubbles does not matter at all even in the vacuum degassing and fining treatment in which the temperature of the molten glass to be treated is low. However, in the vacuum degassing treatment, it is preferable to reduce the volume of the vacuum degassing tank in order to make the apparatus compact and improve workability. For this reason, the load on the refractory furnace material is about 10 times that in the case of the above-described ordinary defoaming fining treatment, and there is a problem that bubbles generated from closed pores generated during operation cannot be ignored. As you did.

That is, when a refractory furnace material is used in the flow path of the vacuum degassing tank 14 for defoaming and defoaming the bubbles in the molten glass G, the refractory furnace material that comes into direct contact with the molten glass G is: Exposure to reduced pressure causes gas in the pores contained in the refractory to be sucked into the vacuum degassing tank 14, and the gas is released from the refractory into the molten glass G, into the molten glass G. Fine bubbles of about 0.1 to 0.2 mm are generated. Bubbles released from the pores of the refractory due to reduced pressure and generated in the molten glass G include bubbles remaining in the molten glass G without floating the high-viscosity molten glass and being sucked out of the vacuum degassing tank. Exists.

In the molten glass G before being subjected to the vacuum degassing treatment,
The generated bubbles are used as a raw material when melting the glass
Sodium carbonate used as sodium carbonate and fining agent
Carbon dioxide generated due to sodium and sodium nitrate
(CO_Two) And sulfur dioxide (SO _Two) Gas and even nitrogen
(N_Two) Gases are the components, and the bubbles of these gases are
Almost removed by vacuum degassing. for that reason,
Bubbles remaining in the molten glass G are resistant to the
Bubbles generated from the pores of the furnace material are dominant. So
To suppress air bubbles generated from pores of refractory furnace material
Need to be

In the refractory furnace material, the erosion proceeds as the molten glass passes, but as the erosion progresses, the pores, ie, closed pores, are further accelerated to be exposed and disappear to generate bubbles. . For this reason, the corrosion resistance of the refractory furnace material, that is, the erosion rate due to the molten glass becomes a problem. In this embodiment, it has been found that the corrosion resistance (erosion rate) also depends on the porosity.

For example, the relationship between the porosity of the refractory and the erosion rate of the refractory due to the molten glass when an alumina-zirconia-silica electroformed refractory is used as the furnace material for the vacuum degassing apparatus of this embodiment is shown in FIG. Shown in Here, the apparent porosity of the refractory furnace material is the porosity of the open pores and is defined by JIS R22.
05. Further, the erosion rate is determined by an erosion acceleration test for measuring the amount of erosion of the refractory furnace material after flowing the molten glass for a predetermined time. Here, the composition of the alumina-zirconia-silica electroformed refractory used was 40% zirconia (ZrO ₂ ) and silica (SiO
₂ ) 11.5%, alumina (Al ₂ O ₃ ) 47%, sodium oxide (Na ₂ O) 1.1%, other 0.4%. The glass used was soda lime silica glass, and the erosion temperature was 1300 ° C.

As shown in FIG. 2, the apparent porosity of the refractory and the erosion rate have a linear relationship and can be approximated by a linear function. Therefore, assuming that the surface area of the vacuum degassing tank is 50 m ² and the flow rate of the molten glass (defoaming treatment amount) is 100 ton / day, apparent porosity is 0.5% (porosity 1.5%) from the function shown in FIG. Is 0.1 mm / day, and the erosion rate at an apparent porosity of 1% (porosity of 2.5%) is 0.1 mm / day.
The erosion rate at an apparent porosity of 3% (porosity of 5%) is 0.6 mm / day, and the erosion rate at an apparent porosity of 5% is extrapolated from the function shown in FIG. It can be determined as 1.0 mm / day.

Here, using an erosion rate of 0.1 mm / day at an apparent porosity of 0.5% (porosity of 1.5%),
When the porosity was calculated, it was 75 cm ^{3 /} day (= 0.01
cm / day × 50 × 10 ⁴ cm ² × 0.015), which is 1.
1 × 10 ⁶ pieces / day (= 75 cm ³ / day / ((4
/3)×3.14×0.025 ³ cm ³ )), and the number of bubbles per 1 kg of glass is approximately 11 (= 1.1 ×
10 ⁶ pieces / day / 10 ⁵ kg / day). Similarly, the calculation results at the apparent porosity of 1% and 3% are shown in Table 1 including the case of the apparent porosity of 0.5%.

[0036]

From Table 1, it can be seen that in the case of the alumina-zirconia-silica electroformed refractory, the apparent porosity is 3% (porosity 5%).
Thus, the number of pieces per 1 kg of glass becomes about 230, which is within the permissible limit for bottle glass and the like. The apparent porosity is 1.0% (porosity 2.5%) and the glass 1k
The number of bubbles per g is about 38, and it can be said that the glass is of sufficiently high quality. Therefore, in order to stabilize and practically use the vacuum degassing treatment of the molten glass using the refractory furnace material, at least the refractory furnace material having a porosity of 5% or less, preferably 3% or less, is decompressed. It is necessary to use the defoaming tank, preferably additionally for the downcomer, more preferably still further for the upcomer.

As described above, when the refractory having a porosity of 5% or less is used for the flow path of the molten glass, the function of the degassing and degassing treatment of the molten glass is sufficiently exhibited, and further, the erosion rate is reduced to reduce the decompression rate. The life of the foam tank 14 also satisfies the required life. In particular, in the case of optical or electronic glass in which the quality of the glass is high and the value of the allowable number of bubbles is strictly limited to a small value, a refractory furnace having a porosity of preferably 3% or less, more preferably 0.5% or less. By using the material, the number of bubbles can be suppressed within an allowable range, and the erosion of the refractory can be suppressed, and the life of the vacuum degassing tank 14 can be maintained. As described above, it is preferable to selectively use refractories having different porosity as the furnace material of the flow channel according to the use of the glass as a product.

The refractory used in the furnace material of the first embodiment of the present invention has a porosity of 5% or less, more preferably 3% or less, and has a high quality even when dissolved in the molten glass G. Deterioration does not cause, for example, coloring or heterogeneity, preferably, the reactivity with the molten glass G is small, and the material itself of the refractory is hardly eroded by the molten glass. It may be something. Examples of such refractories include dense refractories, for example, electroformed refractories having a porosity of 5% or less and fired refractories having a porosity of 5% or less, and preferably having a porosity of 3% or less. It is preferably an electroformed refractory or a fired refractory having a porosity of 3% or less.
An electroformed refractory is a refractory made by electroforming a refractory raw material and then casting it into a predetermined shape.A fired refractory is a refractory formed by molding a refractory raw material and having properties such as a predetermined strength. A refractory that has been heat treated at a predetermined temperature in order to have it.

Here, the porosity of the electroformed refractory is 5%.
Any of the following electroformed refractories may be used, and more preferably, a dense electroformed refractory having a high bulk density of 3% or less in porosity and capable of maintaining a vacuum in the vacuum degassing tank 14. Anything is good. As such electroformed refractories, for example, zirconia-based electroformed refractories, alumina-based electroformed refractories,
Alumina-zirconia-silica (AZS; Al ₂ O ₃ −
ZrO ₂ —SiO ₂ ) -based electroformed refractories. On the other hand, a normal fired refractory has a porosity of about 20%, while a dense fired refractory used in the furnace material of the first embodiment of the present invention has a porosity of 5% or less. The dense fired refractory used in the present invention may be any material as long as it has a porosity of 5% or less, and preferably has a high bulk density with a porosity of 3% or less. What is necessary is just to be a dense fired refractory that can maintain the temperature. For example, dense zirconia-silica-based fired refractories, dense alumina-based fired refractories, and dense alumina-zirconia-
Silica-based fired refractories can be mentioned. α, β-alumina-based electrocast refractories have a porosity of 5% or less,
The furnace material made of the refractory can be used as the furnace material for the vacuum degassing apparatus according to the first aspect of the present invention.

When an electroformed refractory is used in the flow path of the vacuum degassing tank 14, the surface layer of the refractory having a predetermined thickness, preferably 5 mm or more, is polished (scalped) in advance as a refractory furnace material. It is preferred to use. Electroformed refractories tend to have a large number of pores on the surface of the refractory due to entrainment in the air during casting in the molding process, and there are few pores inside the refractory, and the porosity is 1% or less. It is. Table 2 shows the apparent porosity of the refractory surface layer of 0 to 6 mm and the apparent porosity of the refractory surface layer of 6 to 20 mm of the alumina-zirconia-silica-based electroformed refractory at five locations of one refractory. The results obtained by sampling from AE) are shown. Although the sampling site B and the sampling site C have an apparent porosity of 1.0% or more at the surface layer of 0 to 6 mm, the sampling sites A to E at the surface layer of 6 to 20 mm.
It can be seen that the apparent porosity of each of them is 1.0% or less. While the average of the apparent porosity at five places of the surface layer 6 to 20 mm is 0.81% and the deviation is 0.07%,
In the surface layer of 0 to 6 mm, the average of the apparent porosity is 0.87%, and the deviation is 0.34%. Therefore, by polishing (sculpting) the surface layer from 0 to 6 mm, the local porosity variation of the surface layer can be removed, and as a result, the porosity can be made substantially equal to the internal porosity. By polishing (sculpting) the surface layer of the refractory in this way, it is possible to suppress the foaming phenomenon that occurs at the initial stage when the molten glass G comes into direct contact with the refractory.
The defoaming treatment of the molten glass G can be performed smoothly from the initial stage of the start-up. Polishing (scalping) is performed using a known grinder or diamond polishing machine. In addition, polishing (scalping) is performed
Limited to electroformed refractories. This is because the fired refractory, unlike the electroformed refractory, has no higher porosity in the surface layer than in the interior.

The method of constructing a vacuum degassing tank having a predetermined cross-sectional shape, for example, a rectangular cross-section and a predetermined length using a refractory having a porosity of 5% or less is not particularly limited. Three-dimensionally alternately cast electroformed refractories,
That is, a labyrinth structure may be piled up and a joint portion between them may be filled with a joint material to form a tube of a predetermined length, for example, a rectangular tube, or a tube of a short length, for example, a rectangular tube, Cast refractories may be stacked in a row and the joints between them may be filled with joints to form a tube of predetermined length, for example a square tube.

As described above, in the conventional vacuum degassing apparatus 100 as shown in FIG. 5, the portion in contact with the molten glass G is made of platinum alloy or the like in view of low high-temperature reactivity and high-temperature strength. Although a noble metal circular tube (cylindrical) is used, the temperature of the molten glass at the entrance of the apparatus is limited to a predetermined temperature (for example, 1400 ° C.) or less because the pipe is made of a noble metal. From the point of view, the pipe diameter of the defoaming tank 104 cannot be made larger than the predetermined diameter, and as a result, the flow rate of the molten glass G, and hence the defoaming amount, cannot be increased. In addition, in the conventional apparatus, as a result of using a noble metal, the temperature of the molten glass G at the inlet of the apparatus is limited and the flow rate cannot be increased, but the cooling in the apparatus is compensated and the temperature at the outlet of the apparatus is kept constant. Must be heated to
For this reason, a metal that can generate heat, that is, a noble metal must be used.

On the other hand, in the present invention, at least the furnace material for the vacuum degassing apparatus of the first embodiment of the present invention is used for the vacuum degassing tank 14 to eliminate the necessity of forming a circular tube. Is composed of a square tube (square tubular tube),
As shown in FIG. 3, the flow rate can be increased, and the flow rate can be further increased by eliminating the restriction on the size of the square tube. As shown in FIG.
The flow rate Qc when the vacuum degassing tank 104 of 0 is constituted by a circular pipe having a diameter D and the vacuum degassing tank 14 of the vacuum degassing apparatus 10 of the present invention.
Is compared with the flow rate Q in the case of a rectangle (square) having a width D and a height D, assuming that the upper space S for foam breaking is half the cross-sectional area of the tube, and Q / Qc = (D ² / 2 / {π (D / 2) 2/2} = 4 /
Since π = 1.27, in the case of the present invention using a square tube, it is possible to increase the flow rate Q by 1.27 times with the same size and the same pressure loss as compared with the conventional case using a circular tube. it can.

Further, by using a square tube as in the illustrated example, the width is changed from D to (1 + p) D (p) without changing the height D.
> 0) to further increase the flow rate to (1 + p) ²
1.2 times that of the conventional case using a circular tube.
7 (1 + p) can be easily increased by a factor of ² . In addition, when a circular pipe is used, if the depth of the flow path of the molten glass G in the circular cross section is set to half or more of the diameter, the upper space S and the width thereof are sharply reduced. If you use a square tube,
In the rectangular cross section, the width of the upper space S does not change even if the flow path depth of the molten glass G is made half or more of the height, so that an appropriate space can be set according to the amount of foam breaking, and the appropriate depth Can be set, so that the flow rate can be further increased. In the conventional example using the circular pipe, even if the size of the circular pipe is increased for increasing the flow rate, the effect of increasing the flow rate is smaller than that in the illustrated example using the square pipe as compared with the size increase. Nor. In addition, the length L of the predetermined cross-sectional shape used in the present invention, for example, the vacuum degassing tank 14 having a rectangular cross section is not particularly limited, but the depth, type, and viscosity of the molten glass G in the vacuum degassing tank 14 are not limited. In accordance with (temperature), flow rate (processing amount), flow rate, and the like, the molten glass G in which the bubbles in the molten glass G sufficiently float and flow down only for the time that they are destroyed and removed is placed in the vacuum degassing tank 14. The length of staying, that is, the length of time sufficient for the defoaming process may be set.

The riser pipe 16 and the descender pipe 18 are used to maintain the level difference H between the molten glass G in the vacuum degassing tank 14 and the molten glass G in the melting tank 24, respectively. The riser pipe 16 moves the molten glass G that has not been defoamed from the melting tank 24 to the upstream indoor duct 26 by reducing the pressure.
And introduced into the vacuum degassing tank 14. Further, the downcomer pipe 18 draws out the defoamed molten glass G from the vacuum degassing tank 14 and lowers it, and sends it out to the next processing tank (not shown) via the downstream guide duct 28.

Here, the riser pipe 16 and the descender pipe 18 are
As in the case of the conventional apparatus, a precious metal circular pipe such as a platinum alloy may be used. However, from the viewpoint of the throughput of molten glass G and the introduction (inlet) temperature, both of them, particularly the riser 16, are provided in a vacuum degassing tank. 1
Similar to 4, it is preferable to use a refractory having a porosity of 5% or less, for example, using a refractory cylindrical tube having a porosity of 5% or less or a refractory square tubular tube having a porosity of 5% or less. However, it is more preferable to use a refractory rectangular tube having a porosity of 5% or less, just like the vacuum degassing tank 14. The dimensions of the riser pipe 16 and the descender pipe 18 may be appropriately selected according to the flow rate of the molten glass G in the vacuum degassing tank 14, that is, the degassing processing amount in the vacuum degassing apparatus 10.

In the present invention, the vacuum degassing tank 14 is made of a refractory tube having a porosity of 5% or less having a predetermined cross-sectional shape, for example, a rectangular tube having a porosity of 5% or less having a rectangular cross-section. The molten glass G in the vacuum degassing tank 14
Can be increased, and thus the degassing treatment amount in the vacuum degassing apparatus 10 can be increased.
That is, when the amount of the molten glass G flowing into the riser 16 increases, the sensible heat that the molten glass G brings into the vacuum degassing apparatus 10 naturally increases. For this reason, since the flow rate was restricted in the conventional apparatus, the decompression degassing tank 1 by the heating device which was necessary for setting the outlet temperature of the decompression degassing apparatus 10 to a predetermined temperature was used.
4 or the like, especially self-heating can be made unnecessary. Furthermore, in the present invention, it is not necessary to use a noble metal such as a platinum alloy at least in the vacuum degassing tank 14,
The inlet (introduction) temperature of the molten glass G of the vacuum degassing apparatus 10,
That is, the outlet temperature of the melting tank 24 can be increased, and the sensible heat that the molten glass G brings into the vacuum degassing apparatus 10 is further increased. As a result, heating of the vacuum degassing tank 14 and the like by the heating apparatus is unnecessary. Things.

For this reason, in the present invention, the degassing treatment amount, that is, the flow rate of the molten glass G in the vacuum degassing tank 14 (the rectangular cross-sectional flow path) is set to 15 tons / day or more, preferably 20 tons / day. As described above, the molten glass G during the defoaming process
It is preferable to eliminate the need for heating, and to eliminate the need for a heating device therefor. Here, the reason why the amount of defoaming treatment without such a heating device is limited to 15 tons / day or more is that if the amount of inflow glass is small, the temperature of the entire vacuum degassing device of the smallest scale is maintained in a desired temperature range. Because you can't.

When the defoaming processing amount is further increased, the sensible heat brought into the vacuum degassing apparatus 10 by the molten glass G is further increased, so that the outlet temperature of the vacuum degassing apparatus 10, and therefore the next processing tank, especially the molding In some cases, the inlet temperature of the processing tank becomes higher than a predetermined temperature. In this case, it is necessary to cool the molten glass G inside and outside the vacuum degassing apparatus 10 so that the inlet temperature of the forming processing tank, which is the next processing tank, becomes a predetermined temperature. For this reason, in the present invention, when the defoaming treatment amount, that is, the flow rate of the molten glass G is 30 tons / day or more, more preferably 35 tons / day or more, a cooling device is provided in the vacuum degassing apparatus 10. It is preferred to provide. Here, the amount of the defoaming treatment when the cooling device is provided is 30 tons /
The reason for limiting to days or more is that if the size of the vacuum degassing device is minimized from the viewpoint of cost and construction difficulty, the temperature will rise too much when the base material inflow increases, the refractory erosion will increase, This is because the defoaming device cannot reduce the temperature to an appropriate temperature for molding.

In the present invention, the vacuum degassing tank 14 is used.
Since the viscosity of the molten glass G is low and the temperature is preferably high for the defoaming process in the inside, the cooling device 22 is provided at the outlet side of the vacuum degassing tank 14 and the downcomer pipe 18, for example, the vacuum degassing device in the illustrated example. It is preferably provided on the outer periphery of the upper part of the downcomer 18 as shown in FIG. However, in the present invention, the entirety of the vacuum degassing tank 14, the inlet side, other parts, and the riser pipe 16.
It is a matter of course that the cooling device 22 may be provided on the ascending pipe 16, the vacuum degassing tank 14, and the downcoming pipe 18. Also,
As the cooling device 22 used in the present invention, a device in which a cooling tube 22a using water or the like as a coolant can be used as shown in the illustrated example can be used, and the position, direction, interval, size, and the like of the cooling tube 22a are necessary. The coolant may be appropriately set, and a liquid or gas other than water may be used as the refrigerant, but the present invention is not limited to this. Further, in the present invention, the cooling device is not provided in the vacuum degassing apparatus 10, and between the outlet of the downcomer pipe 18 and the inlet of the forming tank (not shown), for example, the downstream guide duct 28 or as necessary. A cooling device is provided in a stirrer (not shown) or the like for promoting homogenization of the defoamed molten glass G to be provided so that the inlet temperature of the forming processing tank, which is the next processing tank, becomes a predetermined temperature. Of course it is good.

By the way, also in the present invention, when the defoaming process is started, that is, when the molten glass G is started to flow, each part of the vacuum degassing apparatus 10, that is, the ascending pipe 16, the vacuum degassing tank 14, and the descending pipe. Since the temperature of 18 is lower than the appropriate temperature, heating is necessary for starting operation, and for this purpose, an operation start heating device (not shown) is provided. Further, although not shown, in order to start operation, it is necessary to operate the siphon principle, and not only the upstream guide duct 26 but also the downstream guide duct 28 must have the molten glass G. It is preferable to provide a bypass (not shown) for flowing the molten glass G to the downstream guide duct 28 from above.

The vacuum degassing apparatus 10 of the present invention can be applied even if the flow rate of the molten glass G is less than 15 tons / day. In this case, as in the conventional apparatus, the sensible heat brought by the molten glass G is small, and the outlet temperature may be lower than a predetermined set temperature due to cooling in the vacuum degassing apparatus 10. It is preferable to provide a heating device 32 for always heating the glass G. Such a heating device 32 includes a heater 32a on the outer periphery of an upper portion of the riser 16 as shown by a dotted line in FIG.
However, the present invention is not limited to this, and any conventionally known heating devices can be used. Further, the position where the heating device 32 is provided is, as shown in FIG.
Either the riser 16 or the inlet side of the vacuum degassing tank 14,
However, the present invention is not limited to this, and the present invention is not limited to this, but may include all or a part of the vacuum degassing tank 14, for example, the outlet side and the downcomer 1
8, or both. When the heating device 32 is provided, it is necessary when the defoaming treatment amount of the molten glass G is less than 15 tons / day, particularly 10 tons / day or less.

In the present invention, the vacuum degassing apparatus 1
The temperature of the inlet (introduction) of the molten glass G, that is, the temperature of the outlet of the melting tank 24, can be increased conventionally, and is not particularly limited. May be selected as appropriate according to the processing amount, the material constituting each part of the vacuum degassing apparatus 10, for example, the type and size of the electroformed refractory. However, considering the heating melting cost in the melting tank 24, the defoaming efficiency of the vacuum degassing apparatus 10, and the cost of heating and cooling inside and outside the apparatus, the exit temperature of the molten glass G in the melting tank 24 is 1300 to 1300. The temperature is preferably 1450 ° C.

Here, the molten glass G to be processed by the vacuum degassing apparatus 10 of the present invention is not particularly limited, and examples thereof include soda lime glass and borosilicate glass. Since the vacuum degassing apparatus 10 can process a large amount of molten glass, it is preferable to treat soda-lime glass requiring a large amount of processing.

The vacuum degassing apparatus for molten glass according to the present invention is basically configured as described above, and its operation will be described below.

First, before starting the operation of the vacuum degassing apparatus 10, after sufficiently heating the flow path 40, the molten glass G in the melting tank 24 is opened in the vacuum degassing apparatus 10, that is, a bypass (not shown) is opened. Then, the liquid is introduced from the upstream guide duct 26 into the downstream guide duct 28, and both lower ends of the riser pipe 16 and the descender pipe 18 are immersed in the molten glass G. After the completion of the immersion, a vacuum pump (not shown) is operated to evacuate the inside of the decompression housing 12 from the suction port 12c.
The inside is evacuated from the suction ports 14a and 14b to reduce the pressure in the vacuum degassing tank 14 to 1/20 to 1/3 atmosphere. As a result, the molten glass G rises in the riser pipe 16 and the downcomer pipe 18 and is introduced into the vacuum degassing tank 14, and the level difference H of the molten glass G between the melting tank 24 and the vacuum degassing tank 14 becomes a predetermined value. Thus, the vacuum space 14s is filled in the vacuum degassing tank 14 to a predetermined depth and evacuated. After this, the bypass is closed.

Thereafter, the molten glass G rises in the rising pipe 16 from the melting tank 24 via the upstream guide duct 26 and is introduced into the vacuum degassing tank 14. The molten glass G is defoamed under a predetermined decompression condition while flowing in the decompression degassing tank 14. That is, in the vacuum degassing tank 14 under a predetermined reduced pressure condition, the bubbles in the molten glass G float in the molten glass G, are blocked by the barriers 30a and 30b, break, and break in the upper space 14s. Ascends and breaks bubbles. Thus, bubbles are removed from the molten glass G. The defoamed molten glass G is led out of the vacuum degassing tank 14 to the downcomer pipe 18, descends in the downcomer pipe 18 and is introduced into the downstream guide duct 28. From the processing tank (not shown) (for example, a forming processing tank).

Here, the refractory having a porosity of 5% or less according to the first embodiment of the present invention is used as a furnace material for the flow path of the vacuum degassing tank 14, so that the refractory furnace of the vacuum degassing tank 14 is used. The number of bubbles generated from the material is kept within an allowable range, the erosion of the refractory furnace material is suppressed, and the life of the vacuum degassing apparatus 10 satisfies the required level. Further, in the illustrated example, at least the vacuum degassing tank 14 has a rectangular cross section and is made of a refractory having a porosity of 5% or less, for example, an electroformed refractory, and thus has a conventional circular cross section, Compared to the defoaming tank 104, even with the same size and the same pressure loss, the flow rate of the molten glass G, that is, the amount of defoaming treatment can be increased. In the illustrated example, only the width is changed without changing the height. Since it can be expanded, it is possible to further increase the flow rate and the defoaming processing amount without increasing the size of the apparatus. Further, in the present invention, since the amount of the defoaming treatment can be increased, the heating of the molten glass G during the defoaming treatment, which was conventionally required, is not required, and the heating device for that purpose is unnecessary. Can be. In the present invention,
A cooling device 22 is provided to cool the molten glass G, and particularly to cool the defoamed molten glass G, so that the melting tank 24 is cooled.
The amount of the defoaming treatment can be further increased without increasing the scale of the apparatus with respect to the scale of the apparatus such as a molding process tank.

Incidentally, the vacuum degassing apparatus for molten glass according to the present invention is not limited to the siphon type vacuum degassing apparatus shown in FIG. 1, but is also disclosed in JP-A-5-262530 and JP-A-7-29.
As a matter of course, the present invention may be applied to a horizontal vacuum degassing apparatus disclosed in Japanese Patent No. 1633. The furnace material and the vacuum degassing apparatus for molten glass used in the vacuum degassing apparatus for molten glass according to the present invention have been described with reference to various embodiments, but the present invention is not limited to the above-described embodiments. Of course, various improvements and design changes can be made without departing from the spirit of the present invention.

[0061]

As described in detail above, according to the first aspect of the present invention, the porosity is 5 instead of the noble metal alloy such as platinum.
% Of the refractory furnace material used in the flow path of the vacuum degassing tank, etc., makes it possible to manufacture a vacuum degassing device that is less expensive than precious metals such as platinum, and to make pores in the refractory. The number of bubbles generated from the glass is suppressed, the number of bubbles in the molten glass is kept within the allowable range, the deterioration of the quality of the glass as a product is prevented, and the erosion of the flow path by the molten glass is further suppressed, which is required for vacuum degassing equipment. It is also possible to satisfy the required flow path life. Further, according to the second aspect of the present invention, the flow rate of the molten glass, and thus the amount of defoaming treatment, can be increased with the same size and the same pressure loss as compared with the conventional one, Since the width alone can be increased without changing the height, the flow rate and the amount of defoaming can be further increased without increasing the size of the apparatus.

Further, according to the second aspect of the present invention, since the amount of the defoaming treatment can be increased, it is not necessary to heat the molten glass during the defoaming treatment, which was conventionally required, and the heating for that purpose is not required. The device can be made unnecessary. In the second aspect of the present invention, a cooling device is provided to cool the molten glass, particularly the defoamed molten glass.
The flow rate of the molten glass and the defoaming amount can be further increased without increasing the scale of the apparatus such as a melting tank and a forming tank.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of one embodiment of a vacuum degassing apparatus for molten glass according to the present invention.

FIG. 2 is a graph showing a relationship between the apparent porosity of the refractory and the erosion rate of the refractory by molten glass.

FIG. 3 shows a vacuum degassing tank of the vacuum degassing apparatus shown in FIG.
FIG.

FIG. 4 is an explanatory diagram for explaining a relationship between a cross-sectional shape and a flow rate of a vacuum degassing tank used in the present invention and a conventional vacuum degassing tank.

FIG. 5 is a schematic cross-sectional view of a conventional vacuum degassing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Decompression degassing apparatus 12 Decompression housing 12a, 12b Leg 12c Suction port 14 Decompression degassing tank 14a, 14b Suction port 14s Upper space 16 Rise pipe 18 Downcomer pipe 20 Insulation material 22 Cooling device 22a Cooling pipe 24 Melting tank 26 Upstream guide Duct 28 Downstream guide duct 30a, 30b Barrier 32 Heating device 32a Heater 40 Flow path G Molten glass

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shun Kijima 1-1-1, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside the Keihin Plant of Asahi Glass Co., Ltd. (72) Atsushi Tanigaki 1-1-1, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Address Asahi Glass Co., Ltd. Keihin Plant (72) Inventor Toshihiro Ishino 1150 Hazawa-cho, Kanagawa-ku, Yokohama

Claims (9)

[Claims] 1. A furnace material for use in at least a portion of a flow path of a vacuum degassing apparatus for defoaming molten glass, which is in direct contact with the molten glass, wherein a refractory having a porosity of 5% or less is used. Furnace material for vacuum degassing equipment for molten glass, characterized in that: 2. The furnace material for a vacuum degassing apparatus for molten glass according to claim 1, wherein the refractory is an electroformed refractory or a densely fired refractory. 3. The electroformed refractory of claim 1, wherein the electroformed refractory is at least one of an alumina-based electroformed refractory, a zirconia-based electroformed refractory, and an alumina-zirconia-silica-based electroformed refractory. The dense fired refractory is at least one of dense alumina-based refractories, dense zirconia-silica-based refractories, and dense alumina-zirconia-silica-based refractories. A furnace material for a vacuum degassing apparatus for molten glass according to the above. 4. The vacuum degassing apparatus for molten glass according to claim 1, wherein said refractory is obtained by polishing at least a surface layer of a surface of an electroformed refractory which is in direct contact with molten glass. Furnace materials. 5. The polishing of the surface layer of the electroformed refractory is at least 5 mm or more, and the apparent porosity of the electroformed refractory whose surface layer is polished at least 5 mm is 1% or less. A furnace material for a vacuum degassing apparatus for molten glass according to the above. 6. A decompression housing to be suctioned under reduced pressure, and a flow passage housed in the decompression housing and through which molten glass flows, and a portion of the flow passage that directly contacts the molten glass,
A vacuum degassing tank for vacuum degassing molten glass, comprising the furnace material for a vacuum degassing apparatus according to any one of claims 1 to 5, which is communicated with the vacuum degassing tank and before degassing treatment. Introducing means for introducing the molten glass into the vacuum degassing tank, and deriving means communicating with the vacuum degassing tank and extracting the molten glass after the defoaming treatment from the vacuum degassing tank. Vacuum degassing equipment for molten glass. 7. The vacuum degassing apparatus for molten glass according to claim 6, wherein the flow path of the vacuum degassing tank has a rectangular cross section. 8. The vacuum degassing apparatus according to claim 1, wherein said introducing means and said deriving means are a rising pipe and a descending pipe, respectively, and at least one of said rising pipe and said descending pipe is decompressed and defoamed according to claim 1. The vacuum degassing apparatus for molten glass according to claim 6 or 7, which is constituted by a furnace material for the apparatus. 9. The vacuum degassing apparatus for molten glass according to claim 6, further comprising a cooling device for cooling the molten glass.