KR101453629B1 - Molten glass manufacturing device, molten glass manufacturing method, and sheet glass manufacturing method using the device and the method - Google Patents

Abstract

The present invention provides a molten glass production apparatus, a molten glass production method, and a method of manufacturing a plate glass using the same, which are suitable for producing high-quality alkali-free glass. The present invention relates to a molten glass production apparatus for producing a molten glass having a glass transition temperature η of 10 ² [dPa · S] and a temperature T _η of 1500 to 1760 ° C., wherein the molten glass producing apparatus has a melting tank, , A plurality of second bubblers and a plurality of first bubblers provided upstream of the second bubbler, wherein the length of the molten glass flow path of the molten bath is L _F , The distance from the downstream end of the molten glass channel to the row of the second bubbler is 0.45L _F to 0.55L _F , the distance between the row of the first bubbler and the row of the second bubbler is 0.4L _F to 0.5L _F , The distance L _P between the heat of the first bubbler and the heat of the second bubbler is 500 to 1000 mm and the distance L _B1 between the heat of the first bubbler and the burner near the upstream side of the heat is 0 to 2000 mm, The heat of the second bubbler and the heat Is just the distance L between _B2 near the burner 800 to 2500mm toward the flow, also it relates to a molten glass producing apparatus, characterized in that L _{B2> B1} L.

Description

TECHNICAL FIELD [0001] The present invention relates to a molten glass manufacturing apparatus, a method of manufacturing a molten glass, and a method of manufacturing a molten glass using the molten glass,

The present invention relates to a molten glass producing apparatus, a molten glass producing method, and a manufacturing method of a plate glass using the same. More specifically, the present invention relates to a molten glass production apparatus, a molten glass production method, and a manufacturing method of a plate glass using the same, for producing high quality non-alkali glass having high homogeneity.

In the production of a glass substrate for a flat panel display (FPD), it is preferable to use alkali-free glass that does not substantially contain alkali metal ions because it improves the insulating property of the glass substrate. Further, the alkali-free glass is preferable for the production of a glass substrate for FPD even in view of a small thermal expansion coefficient.

In the production of a glass substrate for FPD, it is desired to further improve the quality, that is, to manufacture a high-quality glass substrate having high homogeneity. Accordingly, various attempts have been made to improve the homogeneity of the molten glass in the melting tank (melting furnace) where the molten glass is obtained by melting the glass raw material.

In the melting furnace disclosed in Patent Document 1, the melting furnace is divided into the upstream band and the downstream band by the transverse threshold, and the circulation flows of the molten glass (upstream circulation flow and downstream circulation flow) are formed in the respective zones, Homogenization is carried out. More specifically, the glass raw material is dissolved by forming the upstream-side circulation flow in the upstream band and the downstream-side circulation flow is formed in the downstream band to homogenize the molten glass. In the melting furnace disclosed in Patent Document 1, a bubbler is provided on the upstream side of the transverse threshold to control the upstream-side circulation flow and the downstream-side circulation flow.

The melting furnace (melting tank) described in Patent Document 2 does not have a structure corresponding to the crossing threshold in the melting furnace described in Patent Document 1, but it is also possible to use at least one row of bubbler and at least two mutually opposing burners, Melting, and refining.

Japanese Patent Laid-Open No. 9-124323 Japanese Patent Laid-Open No. 7-144923

However, the melting furnace described in Patent Documents 1 and 2 is not always suitable for producing high-quality alkali-free glass.

An index of the melting temperature of the glass is T _η , that is, a temperature at which the glass viscosity η is 10 ² [dPa · S], but the alkali-free glass has a T _η of 1,500 to 1,760 ° C. and an alkali such as soda lime glass It is difficult to homogenize the glass with higher T _侶 than 100 캜. As a result, it is difficult to sufficiently homogenize a glass furnace (such as a glass substrate for FPD) having a strict requirement for homogeneity in a melting furnace having a layout such as soda lime glass disclosed in Patent Documents 1 and 2 for general mass production. .

In addition, as described above, since the non-alkali glass has a higher T _η than an alkali-containing glass such as soda lime glass, the temperature of the molten glass in the melting furnace is inevitably increased. When the temperature of the molten glass is high, the erosion of the molten glass into the furnace structure is strengthened accordingly. Therefore, in the case of alkali-free glass, if there is a step that affects the molten glass flow at the bottom of the melting furnace, such as the crossing threshold in the melting furnace described in Patent Document 1 and the refining band in the melting furnace described in Patent Document 2, Erosion of the step difference due to the molten glass and generation of impurities due to the erosion are problems.

Further, in the case of alkali-free glass, since the temperature of the molten glass in the melting furnace is inevitably increased, if the downstream zone is long as in Patent Document 1 or a large melting furnace as in Patent Document 2 is used, The energy efficiency is disadvantageous. Incidentally, erosion by molten glass and generation of impurities therefrom, and change of the flow rate of molten glass are also problematic.

In order to solve the problems of the prior art described above, it is an object of the present invention to provide a molten glass production apparatus, a molten glass manufacturing method, and a method of manufacturing a plate glass using the same, which are suitable for producing high quality, non-alkali glass having high homogeneity do.

In order to achieve the above object, it has been found that, in order to produce a high-quality, non-alkali glass having a high homogeneity, the relationship between the flow rate of the upstream-side circulation flow in the melting tank for dissolving the glass raw material and the flow rate of the downstream- The inventors of the present invention have found that it is necessary to control them so that they can be controlled.

The present invention is based on the above finding by the inventors of the present invention, and is a molten glass producing apparatus for producing a molten glass having a temperature T _η at which the glass viscosity η is 10 ² [dPa · S] is 1500 to 1760 ° C., The molten glass producing apparatus has a melting tank for melting a glass raw material,

A plurality of first bubblers and a plurality of second bubblers in the width direction of the molten glass channel near the bottom of the melting vessel,

The first bubbler is provided on the upstream side of the molten glass flow path with respect to the second bubbler,

Wherein the melting tank has a burner for heating an upper space of the melting tank,

When the length of molten glass flow path of the melting vessel L _F LA, from the upstream end portion of the molten glass flow path, the distance to the heat of the first bubbler is 0.4L to 0.5L _{F F,} the downstream end of the molten glass flow path The distance between the row of the first bubbler and the row of the second bubbler is from 0.45L _F to 0.55L _F and the distance L _P between the row of the first bubbler and the row of the second bubbler is 500 to 1000mm,

The distance L _B1 between the heat of the first bubbler and the burner in the immediate vicinity of the upstream side of the heat in the flow direction of the molten glass in the melting tank is 0 to 2000 mm,

The distance L _B2 between the heat of the second bubbler and the burner immediately adjacent to the downstream side of the heat in the direction of the flow path of the molten glass in the melting vessel is 800 to 2500 mm,

The present invention also provides a molten glass producing apparatus characterized in that L _B2 > L _B1 .

Further, the present invention is a method for producing molten glass using the apparatus for producing a molten glass, wherein the average flow rate of the gas supplied from the first bubbler is V ₁ [liter / minute] V _{2 < /} RTI _>< RTI ID = 0.0 _> [Liters / minute], and the atmosphere temperature above the first bubbler is T ₁ [° C], and the atmosphere temperature above the second bubbler is T ₂ [° C], the molten glass is produced under the condition that V ₁ > V ₂ and T ₁ > T ₂ .

The present invention also provides a method of manufacturing a glass plate for molding a molten glass obtained by the above-mentioned method for manufacturing a molten glass of the present invention into a glass plate.

The apparatus for producing a molten glass of the present invention and the method for producing a molten glass are suitable for the production of high-quality, non-alkali glass having high homogeneity.

The process for producing a plate glass of the present invention is suitable for the production of a substrate for FPD because it can produce a plate glass having high homogeneity and high transparency.

1 is a cross-sectional view of one embodiment of a melting vessel in an apparatus for producing a molten glass of the present invention.
2 is a plan view of the dissolution tank 10 shown in Fig. However, the upper wall surface of the dissolution tank 10 is omitted.

Hereinafter, the present invention will be described with reference to the drawings.

As described above, T _? Is used as an index of the melting temperature of the glass. Glass according to the present invention the target is, since the _η T is higher than 100 ℃ than the T _η of alkali-containing glass, such as 1500 to 1760 ℃, a typical soda-lime glass, it is difficult to homogenize the molten glass. The apparatus for producing a molten glass of the present invention and the method for producing a molten glass are suitable for promoting homogenization of such molten glass. Specific examples of glass having a T _{? Of} 1,500 to 1,760 占 폚 are particularly alkali-free glass.

From this point of view, the apparatus for producing a molten glass and the method for producing a molten glass of the present invention are suitable for producing a predetermined quantity (20 to 100 tons / day) of a glass product having strict quality requirements, such as a glass substrate for FPD.

Fig. 1 is a cross-sectional view of one embodiment of a melting vessel in the apparatus for producing a molten glass of the present invention, and Fig. 2 is a plan view of the melting vessel shown in Fig. However, in order to facilitate understanding, the upper wall surface of the dissolution tank 10 is omitted.

At the end on the upstream side of the melting tank 10, a glass raw material inlet port 11 is provided. The glass raw material introduced from the inlet 11 is melted by the heating by the burner 15 to become the molten glass G and is held in the melting vessel 10. [ At the downstream end of the melting tank 10, a feed port 12 for feeding the molten glass G to the next process is provided. The delivery port (12) communicates with the conduit (20) on the downstream side.

A plurality of first bubblers 13 and a plurality of second bubblers 14 are provided in the vicinity of the bottom surface of the dissolution tank 10 shown in Figs.

The plurality of first bubblers 13 and the plurality of second bubblers 14 are arranged at predetermined intervals (pitches) in the width direction of the melting vessel 10, more specifically in the width direction of the molten glass channel of the melting vessel 10 Respectively.

The first bubbler 13 is provided on the upstream side of the molten glass flow path with respect to the second bubbler 14. The first bubbler 13 is provided between the heat of the first bubbler 13 and the heat of the second bubbler 14 Respectively.

The pitches of the individual bubblers in the row direction of the first bubbler 13 and the second bubbler 14 and the pitches of the individual bubblers 13 and the rows of the second bubbler 14 Will be described later.

On both sides of the melting vessel 10 shown in Figs. 1 and 2, a burner 15 is disposed above the molten glass G held in the melting vessel 10. The burners 15 are provided at regular intervals throughout the lengthwise direction of the melting tank 10, except for the exceptional portions to be described later.

The melting vessel 10 in the apparatus for producing a molten glass of the present invention is characterized in that the first and second bubblers 13 and 14 and the burner 15 are arranged in a specific arrangement to be described later, (The upstream side circulation stream 100 and the downstream side circulation stream 101) of the molten glass G in the melting tank 10 without providing a step structure that affects the molten glass flow as described in 2, And the flow velocity of the upstream-side circulation flow 100 and the flow velocity of the downstream-side circulation flow 101 can be controlled to have a predetermined relationship.

Melting vessel 10 in the molten glass producing apparatus of the present invention, since there is no stepped structure to the bottom of molten glass flow path where the erosion problem caused by the molten glass, T _η is the production of glass of 1500 to 1760 ℃ Lt; / RTI >

The melting vessel 10 in the apparatus for producing a molten glass of the present invention is characterized in that when the length of the molten glass channel of the melting vessel 10 is L _F , the heat of the first bubbler 13 from the upstream end of the molten glass channel the distance to a 0.4L to 0.5L, and _{F F,} from the downstream end of the molten glass flow path, the distance of the second column to the bubbler (14) 0.45L to 0.55L _{F F.}

Therefore, the length of the melting tank 10 is shorter than that of the conventional melting tank (melting furnace) as described in Patent Documents 1 and 2, and the length of the portion forming the downstream-side circulating flow in the melting tank is also short.

The length L _F of the molten glass channel of the melting vessel 10 of the present invention varies depending on the width of the molten glass channel, but is preferably 10 to 30 m, more preferably 10 to 25 m, and still more preferably 15 to 22 m .

On the other hand, the width of the molten glass channel is preferably 5 to 10 m, more preferably 5.5 to 9 m, and still more preferably 6.5 to 8 m.

In the melting vessel 10 of the apparatus for producing a molten glass of the present invention, the flow rates of the gases 16 and 17 from the first bubbler 13 and the second bubbler 14 are set to a specific relationship described below, The flow rate per unit time of the molten glass flow (downstream side circulation flow 101) in the downstream band is lowered and the flow rate of the upstream side circulation flow 100 and the flow rate of the downstream side circulation flow 101 Can be controlled to have a predetermined relationship. Thus, when producing a molten glass having a T _{? Of} 1500 to 1760 占 폚, it is possible to prevent the dissolution of a heterogeneous layer (a glass layer) having a specific gravity, which is caused by unreacted materials in the glass raw material or volatilization on the surface of the molten glass, It is possible to suppress homogeneity of the molten glass and to obtain homogeneous high-quality molten glass having high homogeneity.

The gases 16 and 17 supplied from the first bubbler 13 and the second bubbler 14 are supplied with the components of the melting vessel 10 such as the molten glass G and the bubblers 13 and 14 It is preferable to use the one that does not adversely affect. Specific examples of such gases include air, nitrogen, oxygen, helium, argon and the like. When platinum or a platinum alloy is used as the material of the bubblers 13 and 14, the gases 16 and 17 supplied from the bubbler 13 and the bubbler 14 are supplied with oxygen such as nitrogen, helium, and argon It is preferable to use a gas which does not contain a gas. Of these, nitrogen is particularly preferable.

In the melting vessel 10, the molten glass flow path of the distance to the heat of the first bubbler 13 from the upstream end and preferably of 0.43L to 0.46L _{F F,} the molten glass from the second bubbler downstream end of the flow path the distance to the heat of the engine 14 is preferably 0.47L to 0.54L _{F F.}

In the melting tank 10, when the distance between the heat of the first bubbler 13 and the heat of the second bubbler 14 is L _P , L _P is 500 to 1000 mm. When L _P satisfies the above range, the effect of promoting the formation of circulating flows of the molten glass G (the upstream circulation stream 100 and the downstream circulation stream 101) in the melting tank 10 is excellent, It is preferable to control the flow rate of the upstream-side circulation flow 100 and the flow rate of the downstream-side circulation flow 101 so as to be in a predetermined relationship.

If L _P is less than 500 mm, the distance between the heat of the first bubbler 13 and the heat of the second bubbler 14 is too close to the circulating flow of the molten glass G in the melting tank 10 It is difficult to control the flow velocity of the upstream circulation stream 100 and the flow velocity of the downstream circulation flow 101 so as to have a predetermined relationship .

If the L _P is 1000mm excess FIG, circulating flow of the first bubbler 13 column and a second bubbler, because the distance between the 14 columns of too wide, the melting vessel 10, the molten glass (G) within the ( The effect of promoting the formation of the upstream-side circulation stream 100 and the downstream-side circulation flow 101 is insufficient and the flow rate of the upstream-side circulation stream 100 and the flow rate of the downstream-side circulation stream 101 are controlled to be a predetermined relationship It is difficult.

In the melting tank 10, it is preferable that L _P is 600 to 800 mm.

In the first bubbler 13 and the second bubbler 14, the pitch p between the individual bubblers in the row direction of the bubbler, that is, the width in the width direction of the molten glass channel of the melting vessel 10 It is preferable that the distance between the individual bubblers of the bubbles is 400 to 700 mm. The effect of promoting the formation of the circulating flows of the molten glass G in the melting vessel 10 (the upstream circulation stream 100 and the downstream circulation stream 101) when the pitch p between the individual bubblers is within the above- And is preferable in controlling the flow rate of the upstream-side circulation flow 100 and the flow rate of the downstream-side circulation flow 101 so as to be in a predetermined relationship, and is also excellent in terms of manufacturing cost.

The distance between the individual bubblers is excessively wide so that the circulation flow of the molten glass G in the melting vessel 10 (the upstream circulation stream 100, the downstream circulation stream 100, (The upstream side circulation stream 100 and the downstream side circulation stream 100) depending on the region in the width direction of the molten glass flow path, and the effect of promoting the formation of the molten glass G may be insufficient, 101) in the flow direction of the molten glass G, which may cause unevenness in the flow velocity of the circulating flow, which is not preferable in terms of homogenization of the molten glass G. Further, it may be difficult to control the flow rate of the upstream-side circulation flow 100 and the flow rate of the downstream-side circulation flow 101 so as to have a predetermined relationship.

On the other hand, even if the pitch p between individual bubblers is made less than 400 mm, the formation of the circulating flows of the molten glass G in the melting tank 10 (the upstream circulation stream 100 and the downstream circulation stream 101) The number of the first and second bubblers 13 and 14 provided in the melting tank 10 is excessively increased from the viewpoint of cost effectiveness and is connected with an increase in the manufacturing cost of the molten glass I do not.

It is preferable that the first bubbler 13 and the second bubbler 14 are arranged so as not to be coaxial with respect to the flow direction of the molten glass in the melting tank 10.

2, the projections of the first bubbler 13 and the projections of the second bubbler 14 are arranged in a zigzag shape. The projections of the first bubbler 13 and the projections of the second bubbler 14 2 The projecting portion of the bubbler 14 does not coaxially exist.

Even if any one of the projections of the first bubbler 13 does not function in this arrangement, the presence of the projecting portion of the second bubbler 14 arranged in a zigzag shape on the downstream side, The effect of promoting the formation of circulating flows (the upstream circulation stream 100 and the downstream circulation stream 101) of the molten glass G in the upstream side circulation stream 10 is not impaired and the effect of promoting the formation of the downstream side circulation flow 100 and the downstream side The flow velocity of the circulation flow 101 can be controlled to be a predetermined relationship.

On both sides of the melting vessel 10 shown in Figs. 1 and 2, burners 15 are provided at regular intervals over the entire longitudinal direction of the melting vessel 10. However, the burner 15 is not provided above the second bubbler 14.

In the present invention, the average flow rate V ₂ of the gas 17 supplied from the second bubbler 14 is set to be smaller than the average flow rate V ₁ of the gas 16 supplied from the first bubbler 13 (Control 1), and the atmosphere temperature T ₂ above the second bubbler 14 is made lower than the atmosphere temperature T ₁ above the first bubbler 13 (control 2) So that the flow rate of the upstream-side circulation flow 100 and the flow rate of the downstream-side circulation flow 101 can be controlled to have a predetermined relationship. Accordingly, homogenization of the molten glass can be promoted when a molten glass having a T _{? Of} 1500 to 1760 ° C is produced, and a high-quality molten glass having high homogeneity can be obtained.

In order to achieve the control (2), it is necessary to dispose the burner 15 immediately adjacent to the heat of the second bubbler 14 and the downstream side of the heat to some extent, as shown in Fig. Therefore, it is necessary to set L _B2 = 800 mm or more.

However, if the heat of the second bubbler 14 and the burner 15 adjacent to the downstream side of the heat are excessively spaced apart, the atmosphere temperature above the second bubbler 14 becomes too low and the homogenization of the molten glass becomes insufficient There arises a problem such as disconnection. Further, the temperature of the molten glass G to be conveyed from the conveying port 12 provided at the downstream end of the dissolution tank 10 is lowered, so that it becomes difficult to degas when the vacuum degassing is performed in the subsequent process do. Therefore, it is necessary to set L _B2 = 2500 mm or less.

Therefore, L _B2 = 800 to 2500 mm. Further, L _B2 = 1000 to 2000 mm is preferable, and L _B2 = 1000 to 1600 mm is more preferable.

In order to achieve the above-described control (2), in the melting tank 10 shown in Fig. 2, the heat of the first bubbler 13 and the heat of the upstream side of the heat toward the right in the near of the burner 15, the distance L _B1, a distance L _B2 between the second bubbler right burner (15) near to the downstream heat and the heat of the engine 14 between, L _B2> L _B1 relationship . That is, although the burner 15 is provided above the first bubbler 13, the burner 15 is not provided above the second bubbler 14. In the melting tank 10 shown in Fig. 2, by setting this arrangement, the atmospheric temperature T ₂ above the second bubbler can be made lower than the atmospheric temperature T ₁ above the first bubbler.

In the present invention, preferably in the L _{B2 B1} -L ≥300mm, more preferably L _{B2 B1} -L ≥500mm, and more preferably L _{B2 B1} -L ≥800mm.

2, the burner 15 is provided above the row of the first bubbler 13, but as long as the relationship of L _B2 > L _B1 is satisfied, the first bubbler 13 and the burner 15 immediately adjacent to the upstream side of the row may be spaced apart to some extent. However, if the heat of the first bubbler 13 is excessively separated from the burner 15 immediately adjacent to the upstream side of the heat, the atmospheric temperature above the first bubbler 13 becomes excessively low and the upstream circulation stream 100 weakens , The melting of the glass raw material becomes insufficient. Further, there arises a problem such that the homogenization of the molten glass G in the region downstream of the dissolution tank 10 becomes insufficient. Therefore, it is necessary to set L _B1 = 2000 mm or less.

Therefore, L _B1 = 0 to 2000 mm. It is also preferable that L _B1 = 500 to 1500 mm.

The pitch between adjacent burners 15 is preferably 600 to 2600 mm, more preferably 800 to 2400 mm, depending on the kind of the burner 15 and the layout of the dissolving tank 10.

The combustion in the burner 15 can be performed by mixing the fuel with the oxygen gas and burning the fuel, or by mixing the fuel with the oxygen gas and the air. By using such a method, the molten glass can contain moisture. In the subsequent process of the molten glass sent from the melting tank 10 to the conduit 20 on the downstream side, when the bubbles in the molten glass are degassed by vacuum degassing, it is preferable that the molten glass contains moisture. Is preferable.

A refractory brick containing ZrO ₂ is used because the constituent material of the portion of the melting vessel 10 in contact with the molten glass G is desired to have excellent heat resistance and corrosion resistance to molten glass, of the bottom surface, the first bubbler, and 13 parts of 0.1L to 0.3L _{F F} to the upstream side from the heat, the ZrO ₂ or less is 97% to 85% in mass%, the glass to the balance being SiO ₂ as a main component It is preferable to use the heat-fused refractory of Fig. Since the temperature of the molten glass flowing through the melting tank 10 is higher on the upstream side than the downstream side and larger than the flow rate from the first bubbler 13 rather than the flow rate from the second bubbler 14, . In this case, the thickness of each of the heat-fused refractories is preferably 50 to 120 mm, and it is preferable to laminate two or three heat-fused refractories. In addition, two to five layers of refractory bricks containing ZrO ₂ can be stacked on the outside of the thus formed heat-fused refractory layer. In addition, it is preferable that all of the portion of the melting tank (10) in contact with the molten glass (G) is composed of the thermally molten refractory of the above composition. Further, each refractory brick can be laminated via a trough material such as alumina, zircon or the like.

It is preferable that cooling means for cooling the refractory bricks by air cooling or water cooling is provided outside the refractory bricks at the bottom of the melting tank 10 because the life of the refractory bricks is improved.

Next, the method for producing a molten glass of the present invention will be described.

In the method for producing a molten glass of the present invention, the molten glass is produced while performing the above-described control (1, 2).

By performing the above control (1, 2), the flow rate per unit time of the downstream-side circulation flow 101 is reduced and the flow rate of the upstream-side circulation flow 100 and the flow rate of the downstream- .

In the method for producing a molten glass of the present invention, V ₁ is preferably 0.5 to 20 liters / minute, more preferably 0.7 to 5 liters / minute, even more preferably 0.9 to 3 liters / minute, / Min is particularly preferable. The V ₂ is preferably 0.3 to 19.8 liters / minute, more preferably 0.4 to 4.8 liters / minute, still more preferably 0.5 to 2 liters / minute, and particularly preferably 0.9 to 2.0 liters / minute.

V ₁ -V ₂ ≥0.2 liter / min is preferable, and V ₁ -V ₂ ≥0.4 liter / min is more preferable, and V ₁ -V ₂ ≥0.6 liter / min is more preferable, and V ₁ -V ₂ ≥1.0 Liter / minute is particularly preferable.

In the method for producing a molten glass of the present invention, the T ₁ is preferably 1590 to 1710 ° C, more preferably 1600 to 1695 ° C. The T ₂ is preferably 1570 to 1690 ° C, and more preferably 1580 to 1675 ° C.

Further, T ₁ -T ₂ is preferably 10 to 35 ° C, T ₁ -T ₂ is more preferably 15 to 30 ° C, and further preferably 19 to 26 ° C.

Further, T ₁ and T ₂ can be measured by the following methods.

(Measurement position)

T ₁ : An intermediate position between a burner immediately upstream of the row of the first bubbler and a burner located immediately upstream of the burner.

T ₂ : an intermediate position between the heat of the second bubbler and the burner immediately adjacent to the downstream side of the bubbler.

(How to measure)

From the observation window provided on the side of the dissolution tank, the temperature of the wall surface in the dissolution tank on the side of the opposite side is measured with a radiation thermometer (for example, CHINO IR-AH3SU (measurement wavelength: 0.65 mu m,? = 1.0)).

In the molten glass producing method of the present invention, when the average flow rate of the upstream-side circulation stream 100 is F ₁ [m / hour] and the average flow rate of the downstream-side circulation flow 101 is F ₂ [m / It is preferable to control F ₁ to 5 to 20 m / hr and F ₂ to 0.5 to 7 m / hr. Thus, homogenization of the molten glass can be promoted when a molten glass having a T _{? Of} 1500 to 1760 ° C is produced, so that a high-quality molten glass having high homogeneity can be obtained.

It is more preferable to control F ₁ to be 8 to 15 m / hour and F ₂ to be 1 to 4 m / hour.

Further, F ₁ and F ₂ can be measured by the following methods.

(Measurement position)

F ₁ : the distance from the upstream end of the molten glass flow path is 0.30L _F to 0.34L _F , and the vicinity of the center in the width direction of the molten glass flow path.

F ₂ : the distance from the downstream end of the molten glass flow passage is 0.22 L _F to 0.30 L _F , and the vicinity of the center in the width direction of the molten glass flow passage.

(How to measure)

The flow of the bubbles in the surface layer of the molten glass is photographed by video, and the moving time with respect to the moving distance of the bubbles is measured to be the flow rate. This procedure is repeated 2-3 times to obtain the average flow rate.

Next, the method of manufacturing the plate glass of the present invention will be described.

In the method of manufacturing a glass plate according to the present invention, the molten glass obtained by the method for producing a molten glass of the present invention is molded into a glass plate. As means for forming a molten glass into a sheet glass, various molding methods such as a float method and a down-draw method can be used. In the case of glass having a T _{? Of} 1500 to 1760 占 폚, the float process is particularly preferable.

In the method of manufacturing a glass plate according to the present invention, the bubbles in the molten glass may be defoamed by vacuum degassing before molding the molten glass obtained by the molten glass production method of the present invention described above into a plate glass.

In the method of manufacturing a plate glass of the present invention, a highly homogeneous molten glass obtained by the method for producing a molten glass of the present invention is molded into a plate glass, so that a plate glass having high homogeneity and high transparency can be obtained.

Since the plate glass manufacturing apparatus of the present invention can be applied to the production of plate glasses for various purposes, it is possible to obtain a plate glass having a high homogeneity and a high transparency, It is particularly preferable to apply it to the production of

Example

A glass raw material is added to the inlet of the dissolution tank 10 shown in Figs. 1 and 2 so as to have a desired composition to produce alkali-free glass having a T _{? Of} 1500 to 1760 占 폚. The dimensions of the respective portions of the dissolution tank 10 shown in Figs. 1 and 2 are as follows.

The length L _F of the molten glass channel: 16 to 25 m

Width of molten glass channel: 5.5 to 9 m

Distance from the upstream end of the molten glass channel to the row of the first bubbler 13: 0.43L _F to 0.46L _F

Distance from the downstream end of the molten glass passage to the row of the second bubbler 14: 0.47 L _F to 0.54 L _F

The distance between the heat of the first bubbler 13 and the heat of the second bubbler 14 L _p : 600 to 800 mm

The pitch (p) of the individual bubblers 13 and 14 in the column direction of the bubbler: 400 to 700 mm

The distance L _B1 between the heat of the first bubbler 13 and the burner 15 immediately upstream of the heat in the direction of the molten glass flow path in the melting vessel is 500 to 1500 mm

The distance L _B2 between the heat of the second bubbler 14 and the burner 15 immediately downstream of the heat in the direction of the molten glass flow path in the melting tank is 1000 to 2000 mm

L _B2 -L _B1? 500 mm

Distance between individual burners in the flow direction of the molten glass in the melting tank: 800 to 2400 mm

The average flow rate V ₁ from the first bubbler 13 and the average flow rate V ₂ from the second bubbler 14 are adjusted to be the following conditions.

V ₁ : 1.8 to 2.6 liters / minute

V ₂ : 0.9 to 2.0 liters / minute

V ₁ -V _2? 0.6 l / min

By the combustion in the burner 15, the atmospheric temperature T ₁ above the first bubbler 13 and the atmospheric temperature T ₂ above the second bubbler 14 are maintained under the following conditions. Also, T ₁ And T ₂ are measured by the above-mentioned method.

T ₁ : 1590 to 1710 ° C

T ₂ : 1580 to 1675 ° C

T ₁ -T ₂ : 10 to 35 ° C

Is measured by the average flow rate F ₁ and the downstream above the average flow rate of the circulating flow F ₂ method (101) of the upstream circulation flow 100 in the melting vessel within 10. The results are as follows.

F ₁ = 8 to 15 m / hour

F ₂ = 1 to 4 m / hour

By performing the above-described condition, the _η T is produced at 1500 to 1760 ℃, high-quality, non-alkali glass with high homogeneity.

Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

This application is based on Japanese Patent Application No. 2009-219347 filed on September 24, 2009, the contents of which are incorporated herein by reference.

≪ Industrial applicability >

The apparatus for producing a molten glass of the present invention and the method for producing a molten glass are suitable for the production of high-quality, non-alkali glass having high homogeneity. Further, the process for producing a plate glass of the present invention is suitable for the production of a substrate for an FPD, since a plate glass having high homogeneity and high transparency can be produced.

10: Melting bath
11:
12: conveyor
13: 1st bubbler
14: second bubbler
15: Burner
16: Gas from the first bubbler
17: Gas from the second bubbler
20: downstream conduit
100: upstream side circulation flow
101: downstream side circulation flow

Claims (10)

And a temperature T _{? Where the} glass viscosity? Of 10 ² [dPa 占 가] is 1500 to 1760 占 폚, wherein the molten glass producing apparatus has a melting tank for melting a glass raw material,
A plurality of first bubblers and a plurality of second bubblers in the width direction of the molten glass channel near the bottom of the melting vessel,
Wherein the first bubbler is provided on the upstream side of the molten glass channel with respect to the second bubbler,
Wherein the melting tank has a burner for heating an upper space of the melting tank,
When the length of molten glass flow path of the melting vessel L _F LA, from the upstream end portion of the molten glass flow path, the distance to the heat of the first bubbler is 0.4L to 0.5L _{F F,} the downstream end of the molten glass flow path from the first distance to the second bubbler and heat 0.45L to 0.55L _{F F,} L is the distance _P is 500 to 1000mm between the columns of the first column and the second bubbler bubbler of,
The distance L _B1 between the heat of the first bubbler and the burner in the immediate vicinity of the upstream side of the heat in the flow direction of the molten glass in the melting tank is 0 to 2000 mm,
The distance L _B2 between the heat of the second bubbler and the burner immediately adjacent to the downstream side of the heat in the direction of the flow path of the molten glass in the melting vessel is 800 to 2500 mm,
The apparatus for producing a molten glass according to claim ₁ , wherein L _B2 > L _B1 . The apparatus for manufacturing a molten glass according to claim 1, wherein a pitch (p) of individual bubblers in a row direction of the bubbler in the first bubbler and the second bubbler is 400 to 700 mm. The molten glass producing apparatus according to claim 1, wherein the first bubbler and the second bubbler are disposed so as not to be coaxial with respect to the flow direction of the molten glass in the melting tank. 3. The molten glass producing device according to claim 2, wherein the first bubbler and the second bubbler are disposed so as not to be coaxial with respect to the flow direction of the molten glass in the melting tank. The melting furnace according to any one of claims 1 to 4, wherein the constituent material of the melting vessel is ZrO ₂ -containing refractory brick, and the molten glass flow path is formed of a mixture of 0.1 A molten glass producing apparatus using a glassy hot-melt refractory material mainly composed of SiO ₂ in a proportion of 85% or more and 97% or less of ZrO ₂ in mass% to L _F to 0.3L _F. 5. The bubbler according to any one of claims 1 to 4, wherein the first bubbler and the second bubbler are made of platinum or platinum alloy, and the gas supplied from the first bubbler and the second bubbler Wherein the molten glass is a gas containing no oxygen. 6. The method according to claim 5, wherein the first bubbler and the second bubbler are made of platinum or platinum alloy, and the gas supplied from the first bubbler and the second bubbler is a molten gas Glass manufacturing device. An apparatus for producing molten glass according to any one of claims 1 to 4, wherein the average flow rate of the gas supplied from the first bubbler is V ₁ (liters / minute) the average flow rate of the gas supplied V ₂ [l / min] LA, and is referred to as the first bubbler to the ambient temperature T ₁ [℃] in above the ambient temperature of the upper portion of the second bubbler T ₂ [ ° C], the molten glass is produced under the condition that V ₁ > V ₂ and T ₁ > T ₂ . The method according to claim 8, wherein the average flow velocity of the upstream circulation flow of the molten glass formed on the upstream side of the first bubbler is F ₁ [m / h] when the average flow rate of the downstream circulation flow F ₂ to La [m / hour], F ₁ = 5 to 20m / hour, F ₂ = 0.5 to molten glass manufacturing method for producing a molten glass under the condition that the 7m / hour. A method for manufacturing a glass plate for molding a molten glass obtained by the method for manufacturing a molten glass according to claim 8 into a glass plate.

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