JP5109086B2 - Molten glass conduit structure and vacuum degassing apparatus using the conduit structure - Google Patents

Description

The present invention relates to a molten glass conduit structure. The conduit structure for molten glass of the present invention can be used as a conduit for molten glass in a glass production apparatus, and can be used as, for example, a riser pipe, a vacuum degassing tank or a downcomer of a vacuum degassing apparatus. The conduit structure of the molten glass of the present invention is suitable as a riser pipe, a vacuum defoaming tank or a downfall pipe of a vacuum degassing apparatus.
In addition, the present invention provides a vacuum degassing apparatus using the conduit structure as a molten glass conduit, particularly as an ascending pipe, a vacuum defoaming tank or a descending pipe, and a vacuum degassing method of the molten glass using the vacuum degassing apparatus. About.

In a glass manufacturing apparatus such as a vacuum degassing apparatus, a refractory brick may be used as a constituent material of a molten glass conduit made of a hollow tube. As the refractory brick, an electroformed brick is usually used because of its excellent heat resistance and corrosion resistance to molten glass.
However, when a molten glass conduit is produced using electroformed bricks, it cannot be produced as a seamless hollow tube. For this reason, for example, a plurality of electroformed bricks formed in a donut shape having an opening at the center is prepared and stacked to form a hollow tube. There are cases where donut-shaped electroformed bricks are used for donut-shaped electroformed bricks, but there are cases where a plurality of electroformed bricks formed in a substantially fan shape or wedge shape are prepared, and these are formed in the circumferential direction. It is more common to assemble along a donut shape.

Therefore, when producing a molten glass conduit using an electroformed brick, joints between the electroformed bricks are unavoidably present on the inner surface of the hollow tube, that is, the flow path directly in contact with the molten glass. Since the electrocast brick has a dense structure with a low porosity, it is considered that there is less oozing of the molten glass from the joint portion than the fired brick. However, it is difficult to completely prevent the molten glass from seeping out from the joint.
It is also conceivable to fill the joints between the electroformed bricks that constitute the flow path in direct contact with the molten glass with joint materials. However, since joint materials generally have a lower density than electroformed bricks, joint materials that are in direct contact with molten glass are more easily eroded than electroformed bricks. For this reason, even if there is little erosion of electroformed brick itself, there exists a problem that the erosion of the joint part between electroformed bricks advances selectively. As a result, it is possible to delay the seepage of the molten glass from the joint part compared to the case where the joint part is not buried, but if the joint material is eroded, the molten glass will exude from the joint part. It becomes.

A backup (support structure) is provided around the molten glass conduit. In the backup, the joints between the electroformed bricks assembled in a donut shape are brought into close contact with each other by pressing the conduit in the center direction. Further, the backup has functions such as heat insulation and reinforcement of the conduit.
For the backup, refractory bricks and solid heat insulating materials are usually used. As the refractory brick, fired brick or the like is usually used from the viewpoint of cost. There are various types of fired bricks, and fired bricks having desired characteristics are used according to functions required for backup. Among them, those excellent in corrosion resistance against molten glass are preferably used. Of the functions required for backup, a solid heat insulating material is preferably used in order to exhibit a heat insulating and heat retaining function.

  Although the solid heat insulating material is satisfactory in terms of heat insulation and heat retention capacity, the corrosion resistance to molten glass is inferior to that of electrocast bricks and fired bricks, which are excellent in corrosion resistance to molten glass. For this reason, when the molten glass which exudes from the joint part between the electroformed bricks which comprise a conduit | pipe reaches | attains the solid heat insulating material which comprises a backup, there exists a possibility that a thermally insulated brick may be remarkably eroded by molten glass. If the solid heat insulating material constituting the backup is eroded, the life of the vacuum degassing apparatus itself may be shortened.

In the vacuum defoaming tank of the vacuum degassing apparatus, the riser pipe and the downfall pipe, in order to prevent leakage of the molten glass from the pipeline, the contact surface between the bricks of the inner surface brick layer is precisely polished to 0.5 mm or less Patent Document 1 discloses that the smoothness is finished and the gap between adjacent bricks is 1 mm or less. Patent Document 1 also discloses that a ramming material is filled in the gap between the inner surface brick layer and the backup brick layer in order to prevent leakage of molten glass from the pipeline.
Also, in order to prevent erosion of the joints of the refractory bricks that are in direct contact with the molten glass and prevent the molten glass from seeping out from the joints, the cross section of the flow path is formed in a polygonal shape, and the flow rate of the molten glass Patent Document 2 discloses a molten glass conduit structure in which a joint portion is formed at a slow corner portion and a cooling pipe is disposed outside the joint portion.

However, in the case of the invention described in Patent Document 1, the ramming material filled in the gap between the inner surface brick layer and the backup brick layer is inferior in density to the electroformed brick. Therefore, the ramming material is gradually eroded when the molten glass oozing out from the joint reaches the ramming material. Therefore, compared with the case where the ramming material is not used, the molten glass that oozes out from the joint portion can be delayed in reaching the backup, but if the ramming material is eroded, the molten glass oozing out from the joint portion. Will reach the backup.
In addition, the invention described in Patent Document 1 precisely polishes the contact surface between the bricks of the inner surface brick layer, and makes the gap between adjacent bricks 1 mm or less, thereby exuding molten glass from the joints. It was expected that the molten glass that leaked and oozed filled the joints, but the joints that originally had a dense structure were gradually eroded by the bricks around the joints, and the gaps gradually May spread. Therefore, it is difficult to prevent the molten glass from exuding from the joint when viewed from the long term.

  On the other hand, in the case of the invention described in Patent Document 2, it is necessary to provide a cooling means such as a cooling pipe on the outside of the joint portion of the refractory brick, so that the conduit structure is complicated. In addition, when water leaks from the cooling pipe, the refractory brick may break due to heat shock. Moreover, there is a possibility that the surroundings may be contaminated by the leaked cooling water. In Patent Document 2, in order to increase the length of the joint without increasing the thickness of the refractory brick, the joint is formed by providing ears protruding outward at both ends of the unit brick forming the joint. It is disclosed that the portion is formed so as to extend radially from the center of the flow path. However, when the ear portion is provided in the refractory brick, the temperature difference between the inner portion and the outer portion of the brick increases, and the brick may break.

JP 2000-7346 A (US Pat. No. 6,334,336) JP 2003-128422 A

In order to solve the above-described problems in the prior art, the present invention provides the conduit with molten glass that exudes from the joints between the electroformed bricks constituting the conduit without cracking the brick without using cooling means. An object of the present invention is to provide a molten glass conduit structure which prevents the solid heat insulating material constituting the backup of the glass from being eroded.
The molten glass conduit structure of the present invention is preferably used as a riser pipe, a vacuum degassing tank or a downcomer of a vacuum degassing apparatus.
The present invention also provides a vacuum degassing apparatus using the molten glass conduit structure of the present invention as a molten glass conduit, in particular, ascending pipe, vacuum degassing tank or downcomer, and melting using the vacuum degassing apparatus. An object of the present invention is to provide a vacuum degassing method for glass.

In order to achieve the above object, the present invention is a molten glass conduit structure comprising a conduit and a backup provided around the conduit,
The conduit is a hollow tube in which electroformed bricks are arranged in the longitudinal direction and the circumferential direction,
The backup is composed of a refractory layer provided outside the conduit, and a heat insulating material layer provided outside the refractory layer,
The refractory layer includes a refractory brick layer formed by disposing a refractory brick along a longitudinal direction and a circumferential direction of the conduit,
The heat insulating material layer includes a solid heat insulating material layer formed by disposing a solid heat insulating material along a longitudinal direction and a circumferential direction of the conduit,
Types of refractory bricks constituting the conduit and the refractory brick layer constituting the conduit so that a portion having a temperature equal to the pour point of the glass is located in the refractory layer when the molten glass passes. The present invention provides a molten glass conduit structure (hereinafter referred to as “the conduit structure of the present invention”), wherein the thickness of the brick in the radial direction and the number of brick layers arranged along the radial direction are selected. To do.

In the conduit structure of the present invention, the refractory brick is preferably selected from the group consisting of fired bricks having any of the following characteristics.
Bulk specific gravity (JIS R2205 (1993)): 1.0 Super thermal conductivity (1000 ° C.): More than 0.3 (W / mK)
Apparent porosity (JIS R2205 (1993)): Less than 60%

In the conduit structure of the present invention, the solid heat insulating material is preferably selected from the group consisting of solid heat insulating materials having any of the following characteristics.
Bulk specific gravity (JIS R2205 (1993)): 1.0 or less Thermal conductivity (1000 ° C.): 0.3 or less (W / mK)
Apparent porosity (JIS R2205 (1993)): 60% or more

The conduit structure of the present invention is preferably used as an ascending pipe, a depressurizing defoaming tank or a descending pipe of a vacuum degassing apparatus having an ascending pipe, a vacuum degassing tank and a descending pipe.
The present invention also provides a vacuum degassing apparatus using the conduit structure of the present invention as a molten glass conduit.
Further, the present invention is a method for degassing molten glass using a vacuum degassing apparatus having an ascending pipe, a vacuum degassing tank and a descending pipe,
At least one of the ascending pipe, the vacuum degassing tank, and the downcomer is provided with a vacuum degassing method for molten glass using the conduit structure of the present invention.

In the conduit structure of the present invention, even when the molten glass exudes from the joint between the electroformed bricks constituting the conduit, while the exuded molten glass passes through the refractory brick layer, the molten glass The temperature is below the pour point of the glass. Therefore, there is no possibility that the molten glass that oozes out from the joint between the electroformed bricks reaches the heat insulating material layer located outside the refractory brick layer. Therefore, there is no possibility that the solid heat insulating material constituting the backup is eroded by the molten glass oozing out from the joint portion between the electroformed bricks.
The conduit structure of the present invention does not require cooling means such as a cooling pipe in order to prevent the molten glass from seeping out. For this reason, the conduit structure is not complicated. Moreover, there is no possibility that the fire brick is broken due to water leakage from the cooling pipe or the surroundings are contaminated by the leaked cooling water.

  In the vacuum degassing apparatus of the present invention, the solid heat insulating material constituting the backup is prevented from being eroded by the molten glass oozing out from the joint portion between the electroformed bricks constituting the conduit. For this reason, the lifetime of an apparatus can be extended significantly.

FIG. 1 is a cross-sectional view of a vacuum degassing apparatus having a molten glass conduit structure according to the present invention. FIG. 2 is a partially enlarged view showing a portion including the rising pipe 13 and the backup 15 of FIG. FIG. 3 is a cross-sectional view of FIG. 2 taken along line aa. FIG. 4 is a view similar to FIG. However, the cross-sectional shape of the conduit structure is different from FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Depressurization degassing apparatus 11: Depressurization housing 12: Depressurization defoaming tank 13: Rising pipe 13a: Electroformed brick 14: Downcombing pipe 15: Backup 16: Refractory material layer 16a: Refractory brick 17: Thermal insulation material layer 17a: Solid refractory Material 18, 19: Extension pipe 18a: Flange for fixing 18b: Flange for sealing 22: Heat insulating material 30: Dissolution tank 40: Treatment tank

The present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a vacuum degassing apparatus having a molten glass conduit structure according to the present invention. The vacuum degassing apparatus 1 shown in FIG. 1 is used for the process of depressurizing the molten glass G in the melting tank 30 under reduced pressure and continuously supplying it to the next processing tank 40.
The vacuum degassing apparatus 1 has a vacuum housing 11 in which the inside is kept in a vacuum state when in use. In the decompression housing 11, a decompression defoaming tank 12 is accommodated and disposed so that its long axis is oriented in the horizontal direction. A rising pipe 13 oriented in the vertical direction is attached to the lower surface of one end of the vacuum degassing tank 12, and a lowering pipe 14 is attached to the lower surface of the other end.
In the vacuum degassing apparatus 1, the vacuum degassing tank 12, the rising pipe 13 and the descending pipe 14 are electroformed brick hollow pipes having a rectangular cross section. Extension pipes 18 and 19 made of platinum or platinum alloy are provided at the lower ends of the ascending pipe 13 and the descending pipe 14, respectively. A backup 15 is disposed around the ascending pipe 13 and the descending pipe 14 in the decompression housing 11.
A heat insulating material 22 is disposed around the vacuum degassing tank 12.

  In the vacuum degassing apparatus 1 shown in FIG. 1, a structure including the uprising pipe 13 and the backup 15 and a structure including the downfalling pipe 14 and the backup 15 are configured as the conduit structure of the present invention. FIG. 2 is a partially enlarged view showing a portion including the rising pipe 13 and the backup 15 of FIG. FIG. 3 is a cross-sectional view of FIG. 2 taken along line aa. Hereinafter, the riser 13 will be described, but the downfall 14 has the same configuration.

  2 and 3, the ascending tube 13 is a hollow tube having a rectangular cross section, and the cross-sectional shape of the hollow portion forming the flow path of the molten glass is circular. The ascending pipe 13 is formed by stacking electroformed bricks 13a. As shown in FIG. 3, by combining two electroformed bricks 13a having a rectangular cross section and a semicircular cutout, a hollow tube structure having a rectangular cross section and a circular cross section of the hollow portion is formed. The The ascending pipe 13 is formed by stacking such hollow pipe structures.

  A fixing flange 18 a provided at the upper end portion of the extension pipe 18 is inserted between the electroformed bricks 13 a constituting the vicinity of the lower end of the rising pipe 13. The extension pipe 18 is made of platinum or a platinum alloy and is a cylindrical body having a circular cross section. The lower end of the ascending pipe 13 (the lower end opening of the decompression housing 11) is sealed by a sealing flange 18b provided near the upper end of the extension pipe 18.

  The kind of the electrocast brick 13a which comprises the riser pipe | tube 13 is not specifically limited, It can select suitably from a well-known thing as an electrocast brick used as a constituent material of the furnace material or the conduit | pipe of molten glass. Specifically, alumina electrocast bricks such as α-alumina electrocast brick, α, β-alumina electrocast brick, β-alumina electrocast brick, zirconia electrocast brick, alumina-zirconia-silica (AZS). ) Electroformed bricks such as quality electroformed bricks.

  As specific examples of the alumina electrocast brick, as α-alumina electrocast brick, Marsnite (registered trademark, the same shall apply hereinafter) A (Asahi Glass Co., Ltd.), Monoflux A (Sango Ban TMM Co., Ltd.), α , Β-alumina electrocast bricks: Marsnite G (manufactured by Asahi Glass Co., Ltd.), Monoflux M (manufactured by Saint-Gobain TM Co., Ltd.), Jaguar M (manufactured by Societe Europian de Produy Lefracter), β -Examples of the alumina electrocast brick include Marsnite U (manufactured by Asahi Glass Co., Ltd.), Monoflux H (manufactured by Saint-Gobain TM Co., Ltd.) and Jaguar H (manufactured by Societe Europian de Produy Lefracter).

  A specific example of the zirconia electrocast brick is X-950 (manufactured by Asahi Glass Co., Ltd.).

  Specific examples of the AZS quality electroformed brick include Zirconite (registered trademark, the same shall apply hereinafter) 1681, Zirconite 1691, Zirconite 1711 (manufactured by Asahi Glass Co., Ltd.), Monoflux S3, Monoflux S4, and Monoflux S5 (Sango Ban Tea M, Inc.) Manufactured), Unicol 501, Unicol 1 (manufactured by Colhard), FC101, FC4101 (manufactured by Walsh), ZAC1681, ZAC1711 (manufactured by Electrorethalter).

  As shown in FIGS. 2 and 3, the backup 15 includes a refractory layer 16 provided outside the riser 13 and a heat insulating material layer 17 provided outside the refractory layer 16. . 2 and 3, the refractory layer 16 is a refractory brick layer in which the refractory bricks 16 a are disposed along the longitudinal direction and the circumferential direction of the rising pipe 13. On the other hand, the heat insulating material layer 17 is a solid heat insulating material layer in which the solid heat insulating material 17 a is disposed along the longitudinal direction and the circumferential direction of the riser 13.

  Here, the refractory layer means a layer including the refractory brick layer described above, and may include a configuration other than the refractory brick layer, for example, an indeterminate refractory. For example, the embodiment described later, i.e., the refractory brick layer is arranged so as to form two or more layers along the radial direction of the riser pipe, and there is no gap between the refractory brick layers. Those filled with regular refractories, those filled with irregular refractories between the riser and the refractory brick layer, and those filled with irregular refractory between the refractory brick layer and the insulating brick layer Is also included in the refractory layer.

  Similarly, in the case of a heat insulating material layer, it means a layer including the above-described solid heat insulating material layer, and may include a configuration other than the solid heat insulating material layer, for example, an amorphous refractory. As an example, the embodiment described later, that is, the solid heat insulating material layer is arranged so as to form two or more layers along the radial direction of the riser pipe, Insulating refractories filled in between, and those filled with indeterminate refractories between the solid heat insulating material layer and the vacuum housing are also included in the heat insulating material layer.

Since the refractory brick 16a is a constituent element of the refractory layer 16 (refractory brick layer) provided between the riser 13 and the heat insulating material layer 17, it needs to be excellent in heat resistance and corrosion resistance against molten glass. Become. For this reason, among the fired bricks, those having excellent corrosion resistance against molten glass (hereinafter referred to as “dense fired bricks”) are used as the firebrick 16a. In the present specification, the dense fired brick means a fired brick having any of the following characteristics.
Bulk specific gravity (JIS R2205 (1993)): 1.0 Super thermal conductivity (1000 ° C.): More than 0.3 (W / mK)
Apparent porosity (JIS R2205 (1993)): less than 60% It is preferable that the dense fired brick used as the refractory brick 16a has all the above three characteristics.

  Specific examples of dense fired bricks include dense alumina-based fired bricks, dense alumina-silica-based fired bricks, dense zirconia-silica-based fired bricks, dense alumina-zirconia-silica-based fired bricks, and the like. . Specific examples of the dense alumina-silica-based fired brick include CWS, CWR, CWK, TB, RG, NB, CH, SR (Asahi Glass Co., Ltd.) and the like. Specific examples of the dense alumina-based fired brick include CWR (manufactured by Asahi Glass Co., Ltd.). Specific examples of the dense zirconia-silica fired brick include, for example, ZR (Asahi Glass Co., Ltd.), and specific examples of the dense alumina-zirconia-silica fired brick include, for example, ZM (Asahi Glass Co., Ltd.). Can be mentioned.

Among the functions of the backup 15, the heat insulating material layer 17 (solid heat insulating material layer) mainly bears the function of heat-insulating the riser 13. For this reason, the heat insulating material layer 17 (solid heat insulating material layer) is comprised with the solid heat insulating material 17a excellent in the heat insulation heat retention capability. In this specification, the solid heat insulating material means a solid heat insulating material having any of the following characteristics.
Bulk specific gravity (JIS R2205 (1993)): 1.0 or less Thermal conductivity (1000 ° C.): 0.3 or less (W / mK)
Apparent porosity (JIS R2205 (1993)): 60% or more As specific examples of the solid heat insulating material satisfying the above characteristics, for example, SP-10, SP-11 (manufactured by Hinomaru Ceramic Co., Ltd.), RA-10, Heat insulation of bricks such as RA-12, RA-13, A-6, A-7, B-6, B-7 (manufactured by Hinomaru Ceramics Co., Ltd.), microtherm molded body (Microtherm Co., Ltd.), kao wool board, etc. Board.
It is preferable that the solid heat insulating material 17a used for the heat insulating material layer 17 has all the above three characteristics.

In FIG. 2 and FIG. 3, when the rising pipe 13 is viewed in the radial direction, one layer of the electroformed brick 13 a constituting the rising pipe 13 is disposed, and one layer of the refractory brick 16 a (fireproof brick 16 a (fireproof) Brick layer) is disposed, and one heat insulating material layer 17 a (solid heat insulating material layer) is disposed as the heat insulating material layer 17. However, these are the positions of the electroformed brick 13 a constituting the riser 13, the refractory brick 16 a (refractory brick layer) constituting the refractory layer 16, and the solid heat insulating material 17 a (solid heat insulating material layer) constituting the heat insulating material layer 17. It shows the relationship, and it is not necessarily necessary to arrange one layer of electroformed brick 13a, one layer of refractory brick 16a (refractory brick layer), and one layer of solid heat insulation material 17a (solid heat insulation material layer). It does not mean.
When producing the rising pipe 13 of a vacuum degassing apparatus using electrocast bricks, a plurality of electroformed bricks 13a having the same composition or different compositions may be used. When using the some electroformed brick 13a, they are arrange | positioned so that two or more layers may be made | formed along the radial direction of the riser pipe 13. As shown in FIG.

In the case of the refractory layer 16, it is preferable to use a plurality of refractory bricks 16 a having the same composition or different compositions and arrange them in two or more layers along the radial direction of the riser 13. Hereinafter, in the present specification, arranging the refractory bricks 16a so as to form two or more layers along the radial direction of the riser pipe 13, "the refractory layer 16 includes two or more refractory brick layers. "
In the case of the heat insulating material layer 17, it is preferable to use a plurality of solid heat insulating materials 17 a having the same composition or different compositions, and arrange them so as to form two or more layers along the radial direction of the riser 13. . Hereinafter, in this specification, disposing the solid heat insulating material 17a so as to form two or more layers along the radial direction of the riser tube 13 is referred to as “a solid heat insulating material layer having two or more heat insulating material layers 17”. Is included. "

The conduit structure of the molten glass of the present invention is such that, when the molten glass passes, the electroformed brick and the refractory brick layer that constitute the conduit are located in the refractory layer so that the temperature is equal to the pour point of the glass. The refractory brick which comprises is selected, It is characterized by the above-mentioned.
The pour point of the glass is a temperature at which the viscosity η of the glass is log η (poise) = 5, and is a temperature that is a measure of the deformation of the glass, and is also referred to as a Lilly Point. 1 poise = 0.1 Pa · s = 0.1 kg / m · s. The pour point of glass varies depending on the type of glass. For example, in the case of non-alkali glass, the temperature is about 900 to 1200 ° C, and in the case of soda lime glass, the temperature is about 850 to 1150 ° C.
When the temperature of the molten glass becomes lower than the pour point of the glass, the viscosity of the glass becomes high and the glass does not flow any more. Therefore, when a portion that reaches a temperature equal to the pour point of the glass is located in the refractory layer when the molten glass passes, the molten glass that has oozed out from the joint portion of the electroformed brick is located near the portion. The flow stops when it reaches. Therefore, there is no possibility that the molten glass that has oozed out from the joint portion of the electroformed brick reaches the heat insulating material layer located outside the refractory layer.

When applied to FIG. 2, when the molten glass passes through the riser tube 13, the riser tube 13 is positioned so that a portion having a temperature equal to the pour point of the molten glass is located in the refractory layer 16 (refractory brick layer). The refractory brick 16a which comprises the electrocast brick 13a which comprises refractory material layer 16 (refractory brick layer) is selected. More specifically, the following points are selected for the electrocast brick 13a constituting the riser 13 and the refractory brick 16a constituting the refractory layer 16 (refractory brick layer).
-Types of electroformed bricks 13a and refractory bricks 16a-Thickness of electroformed bricks 13a and refractory bricks 16a in the radial direction of the rising pipe 13-Electroformed bricks 13a and refractory bricks 16a arranged along the radial direction of the rising pipe 13 Number of Layers The concept for selecting the above points for the electroformed brick 13a and the refractory brick 16a will be described below.

(A) Types of bricks Some electroformed bricks have different thermal conductivities due to different porosity. And the higher the porosity, the lower the thermal conductivity, and the higher the heat insulation capacity. Therefore, when a brick having a high porosity and a low thermal conductivity is used as the electroformed brick 13a constituting the riser tube 13, even if the temperature of the molten glass before passing through the electroformed brick 13a is the same, the porosity is increased. The temperature after passing through the electroformed brick 13a is lower than when a brick having a low thermal conductivity is used.
When applied to FIG. 2, the temperature on the inner wall surface side of the electroformed brick 13a, that is, the glass flow path side in contact with the molten glass becomes the temperature of the molten glass before passing through the electroformed brick 13a. On the other hand, the temperature on the outer wall surface side of the electroformed brick 13a, that is, the wall surface side in contact with the refractory brick 16a becomes the temperature of the molten glass after passing through the electroformed brick 13a. Based on this, in other words, when an electroformed brick having a high porosity and a low thermal conductivity is used, even if the temperature on the inner wall surface of the electroformed brick 13a is the same, the porosity is low and the thermal conductivity is reduced. It can be said that the temperature on the outer wall surface side of the electroformed brick 13a is lower than when a brick with a high rate is used. If the temperature on the outer wall surface side of the electroformed brick 13a is lowered, the temperature of the refractory brick 16a located outside the electroformed brick 13a is naturally lowered.
Some densely fired bricks used as the refractory bricks 16a have different thermal conductivities due to different porosity. Therefore, among the densely fired bricks, if bricks with high porosity and low thermal conductivity are used, even if the temperature on the inner wall surface side of the refractory brick 16a is the same, the porosity is low and the thermal conductivity is high. Compared with the case where a brick is used, the temperature of the outer wall surface side of the refractory brick 16a becomes lower.

(B) Brick thickness in the radial direction of the riser pipe The heat insulation and heat insulation effect by bricks such as electrocast bricks and densely fired bricks varies depending on the thickness of the brick, and the heat insulation and heat insulation effect increases as the brick thickness increases. Therefore, if a brick having a large thickness in the radial direction of the riser 13 is used as the electrocast brick 13a, even if the temperature on the inner wall surface side of the electrocast brick 13a is the same, the thickness in the radial direction of the riser 13 is the same. Compared with the case where brick with small is used, the temperature in the outer wall surface side of the electrocast brick 13a becomes lower. However, when a brick having an extremely large thickness in the radial direction of the riser 13 is used as the electroformed brick 13a, the temperature difference between the inner portion and the outer portion of the brick increases, and the brick may be broken. The same applies to the case of the refractory brick 16a.

(C) The number of brick layers arranged along the radial direction of the riser pipe As described above, the thickness of the electroformed brick 13a in the radial direction of the riser pipe 13 is broken by the temperature difference between the inner part and the outer part. There is a risk that it cannot be made extremely large. However, the improvement of the heat insulation and heat retention effect obtained by increasing the thickness of the brick can also be obtained by increasing the number of electroformed bricks 13a arranged along the radial direction of the riser 13. Therefore, instead of using the electroformed brick 13a having a large thickness in the radial direction of the rising pipe 13, a plurality of electroformed bricks 13a having a small thickness in the radial direction of the rising pipe 13 are used, and these are used in the radial direction of the rising pipe 13. The thickness of the rising pipe 13 in the radial direction may be made approximately the same by arranging the layers so as to form layers. The same applies to the case of the refractory brick 16a.

In other words, the above (b) and (c) are raised so that when the molten glass passes through the riser 13, a portion having a temperature equal to the pour point of the molten glass is located in the refractory layer 16. It can also be said that the total thickness of the bricks in the radial direction of the tube 13 may be selected.
That is, when the electroformed bricks 13a are arranged so as to form two or more layers along the radial direction of the riser tube 13, the total thickness of the electroformed bricks in the radial direction of the riser tube 13 is a predetermined thickness. It is sufficient to select so that The same can be said for the refractory layer 16. In this case, when two or more refractory brick layers are included, the total thickness of the refractory brick layers may be selected to be a predetermined thickness.
In the case of the electroformed brick 13a constituting the rising pipe 13, the total thickness in the radial direction of the rising pipe 13 is preferably 30 to 1000 mm, and more preferably 50 to 500 mm.
On the other hand, in the case of the refractory layer 16, the total thickness of the refractory brick layer in the radial direction of the riser 13 is preferably 50 to 1500 mm, and more preferably 100 to 1000 mm. When the refractory layer 16 contains an amorphous refractory, the total thickness including the thickness of the layer formed by the amorphous refractory is preferably in the above range.

  In the case of the heat insulating material layer 17, the total thickness of the solid heat insulating material layers in the radial direction of the riser 13 is preferably 50 to 1500 mm, and more preferably 100 to 1000 mm. When the heat insulating material layer 17 contains an amorphous refractory, the total thickness including the thickness of the layer formed by the amorphous refractory is preferably in the above range.

In the conduit structure of the present invention, between the riser 13 and the refractory layer 16, more precisely, between the riser 13 and the refractory brick layer, prevention of seepage of molten glass and insulation of the backup 15 are provided. In order to increase the heat retaining capacity, a castable refractory, or an amorphous refractory such as a plastic refractory or a ramming material may be filled. For the same reason, the amorphous refractory may be filled between the refractory layer 16 and the heat insulating material layer 17, more precisely between the refractory brick layer and the solid heat insulating material layer. Further, an amorphous refractory may be filled between the heat insulating material layer 17 and the decompression housing 11, more precisely between the solid heat insulation material layer and the decompression housing 11.
Also, between the electroformed bricks 13 a constituting the riser 13, between the refractory brick layers constituting the refractory material layer 16, or between the solid heat insulating material layers constituting the heat insulating material layer 17, it is indefinite. You may fill with a refractory. The proportion of the amorphous refractory is preferably 50% by volume or less, particularly preferably 30% by volume or less in terms of retention as a structure.

  As mentioned above, although the conduit structure of this invention was demonstrated using figures, the conduit structure of this invention is not limited to the form shown in figure. For example, the electroformed brick conduit is not particularly limited as long as it is at least a hollow tube structure, and may be other than a rectangular cross section. FIG. 4 shows another configuration example of the conduit structure of the present invention, in which the conduit 13 'made of electroformed brick has a circular cross section. In FIG. 4, by combining two electroformed bricks 13a ′ having a semicircular arc shape and having a semicircular cutout inside, a hollow tube structure having a circular cross section and a circular cross section of the hollow portion. Is formed. In FIG. 4, a refractory layer 16 'is provided outside the conduit 13', and a heat insulating material layer 17 'is provided outside the refractory layer 16'. The refractory layer 16 'and the heat insulating material layer 17' each have a circular cross section. The decompression housing 11 'that houses the conduit 13' and its backup (the refractory layer 16 'and the heat insulating material layer 17') also has a circular cross section.

The cross-sectional shape of the electroformed brick conduit may be a shape other than a rectangle or a circle, for example, an elliptical hollow tube, and a polygonal shape other than a rectangle, for example, six It may be a hollow tube such as a square or octagon. The cross-sectional shape of the hollow part forming the flow path of the molten glass may also be a shape other than a circle, for example, an elliptical shape, or a polygonal shape such as a rectangle, hexagon, octagon, etc. Good. When the electroformed brick conduit is a hollow tube having another shape, an electroformed brick having a desired shape may be used according to the cross-sectional shape of the conduit and the cross-sectional shape of the hollow portion.
Moreover, arrangement | positioning of the refractory brick in a refractory material layer and arrangement | positioning of the solid refractory material in a heat insulating material layer can also be suitably selected according to the cross-sectional shape of a conduit | pipe.

In the vacuum degassing method for molten glass of the present invention, the vacuum degassing apparatus using the conduit structure of the present invention is used for at least one of the ascending pipe, the vacuum degassing layer or the descending pipe, and the molten glass is supplied from the melting tank. The molten glass is passed through a reduced-pressure defoaming tank depressurized to a predetermined degree of depressurization to perform degassing under reduced pressure.
Since the riser and downcomer of the vacuum degassing device are placed under reduced pressure, the pressure of the molten glass is applied to the wall of the riser and downcomer, and the glass substrate is external compared to the case of normal pressure. It is easy to leak. Therefore, in the present invention, it is preferable to use the conduit structure of the present invention for at least one of the ascending pipe and the descending pipe, and preferably both, so that the leakage of the glass can be more effectively suppressed.
Moreover, since the vacuum degassing tank is also placed under reduced pressure, the glass is likely to leak as in the case of the riser and downcomer. In addition, since the vacuum degassing tank stores more glass than the riser and downcomer, the refractory layer and the heat insulating material layer are often thick. Furthermore, since the vacuum degassing tank is supported by the refractory layer and the heat insulating material layer, the vacuum degassing tank may become structurally unstable if the glass substrate is leaked. In the present invention, it is preferable to use the conduit structure of the present invention in a vacuum degassing tank because the above problems can be solved.
In the vacuum degassing method for molten glass according to the present invention, it is preferable that the molten glass is continuously supplied to and discharged from the vacuum degassing tank.

In order to prevent a temperature difference from the molten glass supplied from the melting tank, the vacuum degassing tank is heated so that the inside is in a temperature range of 1100 to 1500 ° C., particularly 1250 to 1450 ° C. It is preferable. In addition, it is preferable from the point of productivity that the flow rate of a molten glass is 1-1000 tons / day.
When carrying out the vacuum degassing method, the vacuum housing is vacuum-sucked from the outside by a vacuum pump or the like, thereby maintaining the inside of the vacuum degassing tank disposed in the vacuum housing in a predetermined vacuum state. Here, the inside of the vacuum degassing tank is preferably decompressed to 38 to 460 mmHg (51 to 613 hPa), and more preferably, the inside of the vacuum degassing tank is decompressed to 60 to 253 mmHg (80 to 338 hPa). Is preferred.

The glass to be defoamed according to the present invention is not limited in terms of composition as long as it is a glass produced by a heat melting method. Therefore, alkali glass such as soda lime silica glass represented by soda lime glass or alkali borosilicate glass may be used. However, since it is difficult to remove bubbles during the refining process and is used for applications such as a display glass substrate that require particularly few defects, alkali-free glass is preferred.
Further, in the case of non-alkali glass, it is necessary to raise the temperature during vacuum degassing to a certain temperature, and considering the point, the effect of the present invention is exhibited more greatly.

The dimension of each component of a vacuum degassing apparatus can be suitably selected according to the vacuum degassing apparatus to be used. In the case of the vacuum degassing tank 12 shown in FIG. 1, the specific example of the dimension is as follows. In addition, the outer diameter and inner diameter in a cross-sectional rectangle show the dimension of one side.
Horizontal length: 1-20m
Outer diameter (rectangular section): 1-7m
Inner diameter (rectangular section): 0.2-3m
Specific examples of the dimensions of the ascending pipe 13 and the descending pipe 14 are as follows.
Length: 0.2-6m, preferably 0.4-4m
Outer diameter (cross-sectional rectangle): 0.5 to 7 m, preferably 0.5 to 5 m
Inner diameter (circular cross section): 0.05 to 0.8 m, preferably 0.1 to 0.6 m

Hereinafter, based on an Example, this invention is demonstrated more concretely. However, the present invention is not limited to this.
(Example)
In this embodiment, the vacuum degassing of molten glass is performed using the vacuum degassing apparatus 1 shown in FIG.
In the vacuum degassing apparatus 1, the ascending pipe 13, the descending pipe 14, and their peripheral parts have the structure shown in FIG. 2.
The constituent materials of each part of the vacuum degassing apparatus 1 are as follows.
Decompression housing 11: Stainless steel vacuum deaeration tank 12: Electroformed brick ascending pipe 13, descending pipe 14: Electroformed brick Electroformed brick 13a (AZS electroformed brick: Zirconite 1711 (Asahi Glass Co., Ltd.)) The shape shown in FIG. 3 is formed and stacked along the longitudinal direction of the rising pipe 13.
Extension tubes 18, 19: Platinum

A backup 15 having the configuration shown in FIG. 2 is disposed around the ascending pipe 13 and the descending pipe 14.
That is, the refractory layer 16 is provided outside the riser 13, and the heat insulating material layer 17 is provided outside the refractory layer 16. The refractory layer 16 is a refractory brick layer in which refractory bricks 16 a (dense fired bricks) are arranged along the circumferential direction of the riser 13. The heat insulating material layer 17 is a solid heat insulating material layer formed by disposing a solid heat insulating material 17 a along the circumferential direction of the rising pipe 13. The refractory bricks 16a constituting the refractory brick layer and the solid heat insulating material 17a constituting the solid heat insulating material layer are stacked along the longitudinal direction of each layer. In the heat insulating material layer 17, a microtherm (manufactured by Microtherm) is filled between the solid heat insulating material layer and the decompression housing 11.
Specific configurations of the riser 13 and the refractory layer 16 and the heat insulating material layer 17 constituting the backup 15 are shown in Table 1. The downcomer 14 and its backup 15 have the same configuration.

ＺＲ−ＵＰ：緻密質ジルコニア−シリカ系焼成レンガ（旭硝子株式会社製）
ＣＨ−ＳＫ３４：緻密質アルミナ−シリカ系焼成レンガ（旭硝子株式会社製）
ＴＢ−Ｐ：緻密質アルミナ−シリカ系焼成レンガ（旭硝子株式会社製）
ＳＰ−１１：固形断熱材（日の丸窯業株式会社製）

ZR-UP: Dense zirconia-silica fired brick (Asahi Glass Co., Ltd.)
CH-SK34: Dense alumina-silica fired brick (Asahi Glass Co., Ltd.)
TB-P: Dense alumina-silica fired brick (Asahi Glass Co., Ltd.)
SP-11: Solid heat insulating material (manufactured by Hinomaru Ceramic Co., Ltd.)

The molten glass is subjected to vacuum degassing under the following conditions.
Temperature inside vacuum degassing tank 12: 1400 ° C
Pressure inside the degassing tank 12: 180 mmHg (240 hPa)
Molten glass: Soda lime glass (pour point 920 ° C)
Flow rate: 50 tons / day

At the time of vacuum degassing, the temperature on the inner wall surface of the electrocast brick 13a constituting the riser tube 13, the refractory brick 16a constituting the refractory material layer 16, and the solid refractory 17a constituting the heat insulating material layer 17 and the microtherm The (inner surface temperature) and the outer wall surface temperature (outer surface temperature) are measured using a thermocouple. The results are shown in Table 1. As is clear from Table 1, when the molten glass passes, the portion having a temperature equal to the pour point of the molten glass is located in the refractory layer 16.
Six months after the start of vacuum degassing, the solid refractory 17a constituting the heat insulating material layer 17 shows no sign of erosion by the molten glass. Moreover, the crack of a brick does not arise.

The molten glass conduit structure of the present invention can be used as a molten glass conduit in a glass production apparatus, and is particularly suitable as a riser pipe, a vacuum defoaming tank, or a downcomer pipe of a vacuum degassing apparatus.

It should be noted that the entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2005-238715 filed on August 19, 2005 are cited herein as disclosure of the specification of the present invention. Incorporated.

Claims (11)

A molten glass conduit structure comprising a conduit and a backup provided around the conduit,
The conduit is a hollow tube in which electroformed bricks are arranged in the longitudinal direction and the circumferential direction,
The backup is composed of a refractory layer provided outside the conduit, and a heat insulating material layer provided outside the refractory layer,
The refractory layer includes a refractory brick layer formed by disposing a refractory brick along a longitudinal direction and a circumferential direction of the conduit,
The heat insulating material layer includes a solid heat insulating material layer formed by disposing a solid heat insulating material along a longitudinal direction and a circumferential direction of the conduit,
Types of refractory bricks constituting the conduit and the refractory brick layer constituting the conduit so that a portion having a temperature equal to the pour point of the glass is located in the refractory layer when the molten glass passes. A conduit structure for molten glass, wherein the thickness of the brick in the radial direction and the number of brick layers arranged along the radial direction are selected. The molten glass conduit structure according to claim 1, wherein the refractory brick is selected from the group consisting of fired bricks having any of the following characteristics.
Bulk specific gravity (JIS R2205 (1993)): 1.0 Super thermal conductivity (1000 ° C.): More than 0.3 (W / mK)
Apparent porosity (JIS R2205 (1993)): Less than 60% The molten glass conduit structure according to claim 1 or 2, wherein the solid heat insulating material is selected from the group consisting of solid heat insulating materials having any of the following characteristics.
Bulk specific gravity (JIS R2205 (1993)): 1.0 or less Thermal conductivity (1000 ° C.): 0.3 or less (W / mK)
Apparent porosity (JIS R2205 (1993)): 60% or more   The conduit structure of molten glass according to claim 1, 2 or 3, wherein the total thickness in the radial direction of the conduit is 30 to 1000 mm.   The molten glass conduit structure according to any one of claims 1 to 4, wherein the total thickness of the refractory layers in the radial direction is 50 to 1500 mm.   The conduit structure of molten glass according to any one of claims 1 to 5, wherein the total thickness in the radial direction of the heat insulating material layer is 50 to 1500 mm.   The conduit structure of the molten glass according to any one of claims 1 to 6, which is used as an ascending pipe or a descending pipe of a vacuum degassing apparatus having an ascending pipe, a vacuum degassing tank and a descending pipe.   The molten glass conduit structure according to any one of claims 1 to 7, which is used as a vacuum degassing tank of a vacuum degassing apparatus having an ascending pipe, a vacuum degassing tank and a downcomer.   A vacuum degassing apparatus using the molten glass conduit structure according to claim 1 as a molten glass conduit.   The vacuum degassing apparatus according to claim 9, wherein the temperature of the vacuum degassing tank of the vacuum degassing apparatus is 1100 to 1500 ° C. A method of vacuum degassing molten glass using a vacuum degassing apparatus having an ascending pipe, a vacuum degassing tank and a downcomer pipe,
The vacuum degassing method of the molten glass using the conduit | pipe structure in any one of Claims 1-7 for at least one among the said rising pipe, a pressure reduction degassing tank, and a downflow pipe.

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