KR101221249B1 - Vacuum defoaming apparatus for molten glass - Google Patents

Abstract

This invention provides the pressure reduction defoaming apparatus of the molten glass by which the effect of pressure reduction defoaming was prevented from falling by the enlargement of the cloth layer by overpressure. The internal air pressure is set to less than atmospheric pressure, connected to the vacuum degassing tank which floats and blows bubbles in the supplied molten glass, and the vacuum degassing tank, and suction-raises the molten glass before defoaming and introduces into the vacuum degassing tank. A decompression degassing apparatus which is connected to a rising pipe and the said decompression degassing tank, and is provided with the falling pipe which lowers and pulls out the molten glass after a degassing process from the degassing degassing tank, WHEREIN: The said reduced pressure degassing tank is carried out by at least 2 connection pipes, An atmosphere control unit having a hollow structure to be connected, wherein the atmosphere control unit is provided with an exhaust port for evacuating and depressurizing the inside of the atmosphere control unit, and the atmosphere control unit has the following (1) and The 1st gas supply pipe | tube which satisfy | fills (2) is formed, The vacuum degassing apparatus of the molten glass characterized by the above-mentioned. (1) The gas flow supplied from the said 1st gas supply pipe traverses the virtual area which extended the opening part which the said atmosphere control part and the said connection pipe extends inside the said atmosphere control part along the tube axis direction of the said connection pipe. (2) An imaginary line extending from the distal end of the first gas supply pipe along the tube axis of the gas supply pipe does not pass through the opening formed by the atmosphere control unit and the connection pipe.

Description

Vacuum degassing apparatus of molten glass {VACUUM DEFOAMING APPARATUS FOR MOLTEN GLASS}

This invention relates to the vacuum degassing apparatus of the molten glass for removing a bubble from the molten glass continuously supplied.

Conventionally, in order to improve the quality of the molded glass product, the clarification process which removes the bubble which generate | occur | produced in the molten glass before shape | molding the molten glass which melt | dissolved the raw material in the melting furnace in the shaping | molding apparatus is used.

In this clarification process, a molten glass is introduce | transduced in a reduced pressure atmosphere, the bubble in the molten glass flows continuously growing under this reduced pressure atmosphere, the bubble contained in a molten glass is floated, and a bubble is made from the molten glass surface. The degassing | defoaming method of degassing | defoaming and discharge | emitting from a pressure reduction atmosphere after that is known.

In such a clarification process, various methods have been proposed in order to accelerate the growth of bubbles in the molten glass or to bubble the bubbles.

In patent document 1, in order to improve the performance characteristic of a clarification operation, it is proposed to contain various clarification promoters in a vitrifiable substance, ie, a glass raw material. In addition, Patent Literature 1 gives the properties of the gas on the molten material, that is, the properties of the gas on the molten glass, as elements that affect the growth of bubbles between clarifications under reduced pressure.

In addition, Patent Document 2 discloses a foam breaking means for breaking a foam generated when molten glass encounters a reduced pressure in a clarification chamber. As foam breaking means, use of a mechanical rotating body for expanding and rupturing bubbles and impinging jets on the foam are disclosed.

Japanese Patent Publication No. 2001-515453 Japanese Unexamined Patent Publication No. 2003-89529

Patent Literature 1 discloses a method of changing the properties of the gas on the molten glass, the selection of the air partial pressure, the selection of the atmosphere in which the nitrogen type inert gas is enriched, and the selection of the partial pressure of the nitrogen type inert gas. What kind of property is a gas on a molten glass, and it does not disclose at all whether it promotes bubble growth. Moreover, when clarifying under reduced pressure conditions, since the volatile gas component from the molten glass and the gas component of the bubble contained in the molten glass are actively released, the partial pressure of the selected air and the partial pressure of the inert gas of the selected nitrogen type are There is a problem that it is easily lowered. Moreover, there exists a problem that the gas composition of an atmosphere changes easily from the atmosphere which enriched the selected nitrogen type inert gas.

Moreover, the method of patent document 2 is not necessarily enough in the point of destruction of foam which arises in a clarification chamber. That is, the use of a mechanical rotating body or jets can destroy the foam already present on the molten glass, but causes disorder in the molten glass, resulting in the generation of new bubbles. In addition, although foams can be locally destroyed in the clarification chamber, foams newly generated on the downstream side of the mechanical rotating body or jets cannot be destroyed. Moreover, the use of a mechanical rotating body may be a source of contamination of the molten glass, and the use of jet streams may lower the temperature of the molten glass and reduce the quality of the glass.

In theory, the higher the decompression degree of the atmosphere above the molten glass (the lower the absolute pressure of the atmosphere), the better the effect of degassing degassing, and the bubbles in the molten glass will decrease. In reality, however, when the degree of decompression of the atmosphere (absolute pressure in the atmosphere) reaches a certain stage, the rate of bubble generation exceeds the bubble extinction rate due to blistering, and the bubble layer is enlarged on the molten glass surface, thereby decompressing the pressure under pressure. The ability is degraded. This phenomenon is called enlargement of the fabric layer due to overpressure. As a result, bubbles in the molten glass flow rather increase. Therefore, the range of the decompression degree (absolute pressure of the atmosphere) of the atmosphere which can fully exhibit the effect of decompression defoaming is considerably narrow, and it was a problem that the effect of decompression defoaming is influenced also by external factors, such as a fluctuation of atmospheric pressure.

MEANS TO SOLVE THE PROBLEM In order to solve said problem of the said prior art, this invention prevents the effect of pressure reduction defoaming by the pressure reduction defoaming apparatus excellent in the effect of the pressure reduction defoaming of molten glass, more specifically, the enlargement of the foam layer by excessive pressure reduction. It is an object to provide a vacuum degassing apparatus of the molten glass.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to achieve the said objective, the present inventors know that the gas component which generate | occur | produced by air bubbles | bubble on the molten glass surface stays above the molten glass which distribute | circulates in the pressure reduction degassing tank, and the effect of pressure reduction defoaming falls. Came out. Hereinafter, in this specification, the gas component which generate | occur | produced by bubble | bubble on the molten glass surface is called "gas component from a molten glass," and the gas component from a molten glass stays above the molten glass which distribute | circulates the inside of a pressure reduction degassing tank. What is called "retention of gas component from molten glass" is called.

If the gas component from the molten glass stays, the atmosphere above the molten glass

Since the partial pressure of the gas component from a molten glass becomes high in (upper space of the molten glass inside a pressure reduction degassing tank), the bubble which floated on the molten glass surface does not bubble well, and it is thought that the effect of pressure reduction defoaming falls.

Moreover, the present inventors discovered that the breaking rate of the surface of a molten glass becomes high by eliminating the retention of the gas component from a molten glass, and can suppress the enlargement of the foam layer by overpressure.

This invention is made | formed based on the knowledge of the inventors mentioned above, The internal air pressure is set below atmospheric pressure, it is connected to the vacuum degassing tank which raises and breaks the bubble in the molten glass supplied, and is connected to the said vacuum degassing tank, and defoaming Of a molten glass having a rising pipe suctioned up the molten glass before the treatment and introduced into the vacuum degassing tank, and a falling pipe connected to the vacuum degassing tank, and lowering the molten glass after the degassing treatment from the vacuum degassing tank to derive it. In the vacuum degassing apparatus,

The atmosphere control part of the hollow structure connected with the said pressure reduction degassing tank by at least 2 connection pipe | tubes, The atmosphere control part is provided with the exhaust port for evacuating and decompressing the inside of the atmosphere control part, At least 1 said The 1st gas supply pipe | tube which satisfy | fills following (1) and (2) in the relationship with the said connection pipe is formed, The pressure reduction defoaming apparatus of the molten glass (henceforth "the pressure reduction defoaming apparatus of this invention") To provide.

(1) The gas flow supplied from the said 1st gas supply pipe traverses the virtual area which extended the opening part which the said atmosphere control part and the said connection pipe extends inside the said atmosphere control part along the tube axis direction of the said connection pipe.

(2) An imaginary line extending from the distal end of the first gas supply pipe along the tube axis of the gas supply pipe does not pass through the opening formed by the atmosphere control unit and the connection pipe.

In the vacuum degassing apparatus of this invention, when making the number of the said connection pipes into X, it is preferable that the number of the said 1st gas supply pipes is X-1 or less (however, the number of the said 1st gas supply pipes is 1 or more).

In the vacuum degassing apparatus of this invention, it is preferable that the gas flow supplied from a said 1st gas supply pipe is a low moisture gas flow of 60 mol% or less of water vapor concentration.

In the vacuum degassing apparatus of this invention, it is preferable that the 2nd gas supply pipe which supplies the low moisture gas of 60 mol% or less of water vapor concentration to the upper space of the molten glass in the said vacuum degassing tank is further formed.

In the pressure reduction degassing apparatus of this invention, the pressure difference generate | occur | produces between an atmosphere control part and a pressure reduction degassing tank by the venturi effect which generate | occur | produces a gas flow so that it may cross a virtual region from a 1st gas supply pipe | tube, and this pressure difference causes an atmosphere control part. And a gas stream circulating in the vacuum degassing tank is generated. By this gas flow, retention of the gas component from a molten glass can be eliminated. The retention of the gas component from a molten glass is eliminated, and the fall of the effect of pressure reduction defoaming is prevented.

Moreover, since the retention of the gas component from the molten glass is eliminated, the enlargement of the cloth layer due to overpressure is less likely to occur. As a result, the pressure reduction degree in a pressure reduction degassing tank can be made higher, and the effect of pressure reduction defoaming can be improved.

In the case where a low moisture gas having a water vapor concentration of 60 mol% or less is used as the gas supplied from the first gas supply pipe, in addition to the effect that the retention of the gas component from the molten glass is eliminated, in an atmosphere above the molten glass in the vacuum degassing tank, The effect of reducing the water vapor concentration is expected. By reducing the vapor concentration of the atmosphere, it is possible to prevent the bubble layer on the surface of the molten glass in the vacuum degassing tank from being enlarged and to generate a dolby, thereby further improving the effect of vacuum degassing.

Moreover, since the vapor concentration of the atmosphere is reduced, volatilization of specific components which are liable to volatilize in molten glass, for example, B, Cl, F, S, etc. can be suppressed, and the change of the glass composition by volatilization of these components can be suppressed. Can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows one structural example of the vacuum degassing apparatus of this invention.
2 is a partially enlarged view showing the vicinity of the virtual region 19 of the vacuum degassing apparatus 10.
3 is a partially enlarged view similar to FIG. 2.
4 is a partially enlarged view similar to FIG. 2.
FIG. 5 is a partially enlarged view similar to FIG. 2.
FIG. 6 is a partially enlarged view similar to FIG. 2.
FIG. 7 is a partially enlarged view similar to FIG. 2.
It is sectional drawing which shows the other structural example of the vacuum degassing apparatus of this invention.

Carrying out the invention  Best form for

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

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows one structural example of the vacuum degassing apparatus of this invention. The pressure reduction degassing apparatus 10 shown in FIG. 1 has the pressure reduction defoaming tank 11 which made the cylindrical shape. The inside of the pressure reduction degassing tank 11 is set to less than atmospheric pressure, and makes the bubble in the supplied molten glass G float and break up. The rising pipe 12 and the downfalling pipe 13 are connected to the vacuum degassing tank 11. The riser 12 is a means for introducing molten glass G that suction-raises the molten glass G before the defoaming treatment and introduces the molten glass G into the vacuum degassing tank 11. For this reason, the lower end part of the riser 12 is immersed in the molten glass G in the upstream pit 220. The molten glass G is supplied from the dissolution tank 200 to the upstream pit 220. On the other hand, the downcomer 13 is a derivation means of the molten glass G which descend | flows the molten glass G after degassing | defoaming process from the pressure reduction degassing tank 11, and is guide | induced. For this reason, the lower end of the downcomer 13 is immersed in the molten glass G in the downstream pit 240. The molten glass G in the downstream pit 240 is led to the processing tank (not shown) of a post process.

Hereinafter, when it says "upstream" and "downstream" in this specification, it means the upstream and downstream in the flow direction of the molten glass G which distributes the pressure reduction degassing apparatus 10.

In addition, although not shown in figure, the pressure reduction degassing tank 11 is normally accommodated in the pressure reduction housing, and the pressure inside the pressure reduction degassing tank 11 is maintained in the pressure reduction state below atmospheric pressure by vacuum-reducing the pressure reduction housing. On the other hand, when the pressure reduction degassing tank 11 is not accommodated in the pressure reduction housing, the pressure reduction degassing tank 11 is carried out by aspirating the upper space of the molten glass G of the pressure reduction degassing tank 11 using a pressure reduction pump etc. The internal air pressure is kept at a reduced pressure below atmospheric pressure.

The vacuum degassing apparatus 10 of this invention has the atmosphere control part 14 connected with the vacuum degassing tank 11 by the at least 2 connection pipes 15 and 16. FIG. The atmosphere control unit 14 has a hollow structure, and an exhaust port 17 for evacuating the inside of the atmosphere control unit 14 to reduce the pressure is formed. The atmosphere control part 14 forms the path | route of the gas flow part 120 which circulates through the atmosphere control part 14 and the upper space of the molten glass G in the pressure reduction degassing tank 11. As shown in FIG. Therefore, in the pressure reduction degassing apparatus 10 of this invention, the pressure inside the pressure reduction degassing tank 11 is maintained in the pressure reduction state below atmospheric pressure by evacuating and depressurizing the inside of the atmosphere control part 14 from the exhaust port 17. FIG. When the decompression degassing apparatus 10 has a decompression housing, by depressurizing | suctioning a decompression housing, the inside of the atmosphere control part 14 is exhausted and depressurized from the exhaust port 17, and the air pressure in the decompression degassing tank 11 is reduced to less than atmospheric pressure. Stays in the state. On the other hand, when the pressure reduction degassing tank 11 does not have a pressure reduction housing, the pressure inside the pressure reduction degassing tank 11 is reduced by evacuating the inside of the atmosphere control part 14 from the exhaust port 17 using a pressure reduction pump etc., and depressurizing it. Maintain the reduced pressure below atmospheric pressure.

Here, since the atmosphere control part 14 forms the path | route of the atmosphere control part 14 and the gas flow 120 which circulates through the upper space of the molten glass G in the pressure reduction degassing tank 11, the connection pipe 15 , 16 needs to be connected to the pressure reduction degassing tank 11 above the liquid level of the molten glass G in the pressure reduction degassing tank 11. For this reason, it is a preferable aspect to arrange | position the atmosphere control part 14 above the pressure reduction degassing tank 11 as shown in FIG. However, if the connection pipes 15 and 16 are connected with the pressure reduction degassing tank 11 above the liquid level of the molten glass G in the pressure reduction degassing tank 11, the atmosphere control part 14 will reduce the pressure reduction degassing tank 11 You may arrange | position to the side of.

Moreover, in order to form the path | route of the gas flow part 120 which circulates through the atmosphere control part 14 and the upper space of the molten glass G in the pressure reduction degassing tank 11, connection pipes 15 and 16 are at least two. I need a dog. In addition, in the pressure reduction degassing apparatus 10 shown in FIG. 1, although the pressure reduction degassing tank 11 and the atmosphere control part 14 are connected in two connection pipes 15 and 16, a pressure reduction degassing tank is carried out by three or more connection tubes. You may connect the 11 and the atmosphere control part 14.

Moreover, when the temperature of the gas flow 120 which flows into the pressure reduction degassing tank 11 is low, since there exists a possibility that it may adversely affect the molten glass G in the pressure reduction degassing tank 11, the atmosphere control part 14 and It is preferable that the connection pipes 15 and 16 have a heating mechanism. However, it is not necessary to necessarily provide a heating mechanism in the atmosphere control part 14 and all the connection pipes 15 and 16, and the connection pipe of the side which the gas flow 120 flows into the pressure reduction degassing tank 11 at least (FIG. In the case of 1, when a heating mechanism is formed in the connection pipe 15, the gas stream 120 with low temperature flows into the pressure reduction degassing tank 11, and it adversely affects the molten glass G in the pressure reduction degassing tank 11. It can solve the concern that it may cause.

In the vacuum degassing apparatus 10 of this invention, the 1st gas supply pipe 20 which supplies a gas in the atmosphere control part 14 is provided. Here, the first gas supply pipe 20 satisfies the following (1) and (2) in relation to at least one connection pipe (in the case of FIG. 1, the connection pipe 16).

(1) The virtual region 19 which extended the opening part 18 which the atmosphere control part 14 and the connection pipe 16 make into the atmosphere control part 14 along the tube axis direction of the connection pipe 16 (FIG. 1) In this case, the gas 100 supplied from the first gas supply pipe 20 traverses the region above the opening 18 in the atmosphere control unit 14.

(2) The atmosphere control part 14 and the connection pipe 16 form the imaginary line 21 (refer FIG. 5) extended along the tube axis of the gas supply pipe 20 from the front end of the first gas supply pipe 20. It does not pass through the opening 18.

The reason why it is necessary to satisfy (1) and (2) is described below.

When the gas stream 100 is supplied from the first gas supply pipe 20 so as to cross the virtual region 19 above the opening 18, the first gas supply pipe 20 is connected according to the Bernoulli law (formula (1)). The pressure in the vicinity of the outlet drops, and a Venturi effect occurs.

p / ρ + v ² / 2g + z = const (1)

p: pressure Pa around the outlet of the first gas supply pipe 20, ρ: density of the gas stream 100 (kg / m 3), g: gravitational acceleration (m / s), v: gas stream 100 Flow velocity (m / s), z: height of the outlet portion of the first gas supply pipe 20 in the atmosphere control unit 14 (height from the bottom of the atmosphere control unit) (m)

As a result, a pressure gradient occurs between the pressure reduction degassing tank 11 and the pressure difference which the pressure in the vicinity of the opening part 18 becomes low compared with the pressure reduction defoaming tank 11 arises. By this pressure difference, the pressure in the vicinity of the opening part 18 (that is, the pressure of the connection pipe 16 side) becomes low, and the pressure reduction degassing tank 11 is opened from the opening part which the atmosphere control part 14 and the connection pipe 15 make. A pressure gradient occurs in the region passing through the opening 18. As a result, the gas flow which circulates the upper space of the atmosphere control part 14 and the molten glass G in the pressure reduction degassing tank 11 (henceforth "gas flow which circulates an atmosphere control part and a pressure reduction degassing tank") ( 120) occurs.

Here, the flow rate v of the gas flow 100 required to generate a pressure difference sufficient to generate the gas flow 120 circulating the atmosphere control unit and the degassing degassing tank is the density ρ of the gas flow 100, the atmosphere control unit. Although it also differs according to the height z of the exit part of the 1st gas supply pipe 20 in the inside of 14, and the area A of the opening part 18, when the flow velocity v of the gas stream 100 satisfies following formula (2) The pressure difference sufficient to generate the gas flow 120 circulating through the atmosphere control unit and the reduced pressure degassing tank is generated.

v> A / 0.031 × [5.487 × 10 ^-6 × (1 / 56.353-1 / ρ) + 19.6 × (0.163-z) +7.5 ² ] ^1/2 (2)

As for the flow velocity v of the gas stream 100, it is more preferable to satisfy following formula (3), and it is still more preferable to satisfy following formula (4).

v> A / 0.031 × [5.487 × 10 ^-6 × (1 / 56.353-1 / ρ) + 19.6 × (0.163-z) +8.4 ² ] ^1/2 (3)

v> A / 0.031 × [5.487 × 10 ^-6 × (1 / 56.353-1 / ρ) + 19.6 × (0.163-z) +9.8 ² ] ^1/2 (4)

As a result of the gas flow 120 circulating through the atmosphere control unit 14 and the vacuum degassing tank 11, the retention of the gas component from the molten glass G is eliminated. That is, the gas component from the molten glass G does not stay, but is transferred to the atmosphere control part 14 by the gas flow 120. The gas component from the molten glass G transferred to the atmosphere control part 14 is discharged | emitted from the exhaust port 17 to the outside. A part of the gas component from the molten glass G transferred to the atmosphere control part 14 may be moved by the gas flow 120, and may return to the upper space of the molten glass G in the pressure reduction degassing tank 11, The gas component 120 which circulates the atmosphere control part 14 and the pressure reduction degassing tank 11 of the molten glass G in the pressure reduction degassing tank 11 exists, and the gas component from the molten glass G is a gas. In terms of dilution by the stream 120, the risk of retention of the gas component from the molten glass G is minimized. In addition, since the gas component from the molten glass G is diluted by the gas flow 120, it adheres in the vacuum degassing apparatus 10 in the process of cooling the gas component from the molten glass G, or the exhaust port 17 After being released from, it is prevented from adhering to the system.

When the gas component from the molten glass G stays, since the partial pressure of the gas component from the molten glass G increases in the atmosphere above the molten glass G in the pressure reduction degassing tank 11, the molten glass G ) Bubbles floating on the surface are less likely to be broken, and the effect of reduced pressure defoaming is deteriorated.

In the vacuum degassing apparatus 10 of this invention, since the retention of the gas component from the molten glass G is eliminated, the effect fall of vacuum degassing | defoaming does not occur, and the effect of pressure reduction defoaming is excellent.

Moreover, when the gas component from molten glass G stays, enlargement of the foam layer by overpressure will occur, and the effect of pressure reduction defoaming will fall significantly, but in the pressure reduction defoaming apparatus 10 of this invention, molten glass G Since the retention of the gas component from the solution is eliminated, it is possible to suppress the enlargement of the fabric layer due to excessive depressurization even if the pressure reduction degree of the vacuum degassing tank 11 is higher than before. Therefore, the pressure reduction degree of the pressure reduction degassing tank 11 can be made higher than before (the absolute pressure of the pressure reduction degassing tank 11 can be made lower than before), and the effect of pressure reduction defoaming can be heightened further.

As shown in FIG. 1, when the gas flow 120 which circulates the atmosphere control part 14 and the pressure reduction degassing tank 11 generate | occur | produces, the connection pipe 16 discharges the gas stream 120 from the pressure reduction degassing tank 11 The derivation gas flow lead-out tube is formed, and the connection pipe 15 forms a gas flow introduction tube through which the gas flow 120 is introduced into the pressure reduction degassing tank 11. Therefore, when it has two connection pipes 15 and 16 like the vacuum degassing apparatus 10 shown in FIG. 1, the 1st gas which satisfy | fills said (1), (2) in relationship with either connection pipe | tube. It is necessary to form a supply pipe, and in the relationship with the other connection pipe, the first gas supply pipe that satisfies the above (1) and (2) should not be formed. On the other hand, when the pressure reduction degassing apparatus has three or more connection tubes, although the 1st gas supply pipe which satisfy | fills said (1) and (2) may be formed in relationship with two or more connection tubes, at least 1 connection tube and In the relation, the first gas supply pipe satisfying the above (1) and (2) should not be formed.

That is, in the vacuum degassing apparatus of this invention, when making the number of connection pipe | tubes into X, the number of 1st gas supply pipes needs to be X-1 or less (however, the number of 1st gas supply pipe | tubes is 1 or more).

In order to generate a pressure difference in which the pressure in the vicinity of the opening 18 is lower than the pressure reduction degassing tank 11, the gas stream 100 supplied from the first gas supply pipe 20 crosses the virtual region 19. Needs to be. In FIG. 1, the tip of the first gas supply pipe 20 is located in the virtual region 19, and supplies the gas flow 100 toward the upstream direction so as to cross the virtual region 19. FIG. 2 is a partially enlarged view showing the vicinity of the virtual region 19 of the vacuum degassing apparatus 10, and the position of the tip of the first gas supply pipe 20 is different from that in FIG. In FIG. 2, the front end of the first gas supply pipe 20 is located downstream from the virtual region 19, and supplies the gas flow 100 toward the upstream direction. The gas flow 100 is supplied toward the upstream direction so as to traverse the imaginary region 19. Such arrangement may be sufficient as long as the flow velocity of the gas flow 100 is sufficiently large and the gas flow 100 can be supplied to cross the virtual region 19.

In the vacuum degassing apparatus 10 of FIG. 1, the upstream end of the first gas supply pipe 20 inserted from above the atmosphere control unit 14 is curved in the upstream direction so as to traverse the virtual region 19. The gas stream 100 was supplied in the direction, but the first gas supply pipe was inserted in the horizontal direction from the downstream end surface of the atmosphere control unit 14, and the gas stream 100 was crossed so as to traverse the virtual region 19. The gas stream 100 may be supplied.

3 is a partial enlarged view similar to FIG. 2, the gas supply 100 being supplied downstream from the first gas supply pipe 20 whose tip is located downstream from the virtual region 19. In this case, since the gas flow 100 does not cross the imaginary region 19, the pressure in which the pressure in the vicinity of the opening 18 is lower than that of the reduced pressure degassing tank 11 without satisfying the above (1). Can't generate a car. Even in the same arrangement as that in FIG. 3, when the front end of the first gas supply pipe 20 is located upstream from the virtual region 19 and the gas flow 100 is supplied toward the downstream direction, the gas flow 100 is a virtual region. Since crossing (19) is satisfy | filled, it can satisfy | fill said (1), and can generate the pressure difference which pressure becomes low compared with the pressure reduction degassing tank 11 in the pressure of the opening part 18.

4 is a partial enlarged view similar to FIG. 2, wherein the direction of the tip of the first gas supply pipe 20 is different from that in FIG. 2 and faces obliquely downward. In this case, since the gas flow 100 supplied from the 1st gas supply pipe 20 is supplied toward the bottom of the atmosphere control part 14 ahead (downstream) of the virtual area 19, the gas flow 100 Does not traverse the imaginary region 19, does not satisfy the above (1), and a pressure difference in which the pressure in the vicinity of the opening 18 is lower than that of the reduced pressure degassing tank 11 can not be generated.

In order to generate a pressure difference in which the pressure in the vicinity of the opening 18 is lower than the pressure reduction degassing tank 11, the gas flow 120 supplied from the first gas supply pipe 20 crosses the virtual region 19. It is necessary that the gas flow 100 is not blown into the connecting pipe 16. For this reason, it is necessary to arrange | position the 1st gas supply pipe 20 so that the virtual line 21 extended along the tube axis of the gas supply pipe 20 from the front-end | tip of the gas supply pipe 20 may not pass through the opening part 18. FIG. There is. FIG. 5 is a partially enlarged view of the vicinity of the virtual region 19 of the vacuum degassing apparatus 10 shown in FIG. 1. In FIG. 5, the imaginary line 21 extends in the horizontal direction toward the upstream direction and does not pass through the opening 18 to satisfy the above (2).

FIG. 6 is a partially enlarged view similar to FIG. 5, because the direction of the tip of the first gas supply pipe 20 is different from that of FIG. 5, and the imaginary line 21 is obliquely downward and passes through the opening 18. The above (2) is not satisfied.

FIG. 7 is a partial enlarged view similar to FIG. 6, wherein the imaginary line 21 faces obliquely downward, and the height of the first gas supply pipe 20 in the atmosphere control unit 14 is the gas supply pipe 20 of FIG. 6. Since it is different from the virtual line 21, the virtual line 21 does not pass through the opening part 18, and it satisfy | fills said (2). Similarly, even when the imaginary line 21 obliquely faces downward, even if the angle where the imaginary line 21 faces obliquely downward is small compared with the gas supply line 20 of FIG. 6, even if it does not pass through the opening part 18. FIG. The above (2) is satisfied.

The vacuum degassing apparatus of this invention should just arrange | position a 1st gas supply pipe so that said (1) and (2) may be satisfied, It is not limited to the aspect shown and the aspect demonstrated above. Although the supply direction of the gas stream 100 was an upstream direction or a downstream direction in the aspect shown above and the aspect demonstrated above, the supply direction of the gas stream 100 is a direction other than these, for example, the front direction of a figure. Or inward direction may be sufficient. In this case, the 1st gas supply pipe 20 is arrange | positioned with respect to the opening part 18 in the front or front of the figure, and the gas flow 100 is supplied in the forward direction or inward direction so that the virtual area 19 may be crossed. .

Moreover, although the gas stream 100 is supplied in the horizontal direction or obliquely downward in the aspect shown in figure, you may supply the gas flow obliquely upward. However, in order for the pressure near the opening part 18 to generate | occur | produce the pressure difference which pressure becomes low compared with the pressure reduction degassing tank 11 effectively, the supply direction of the gas stream 100 is orthogonal to the tube axis of the connection pipe 16. Direction, ie horizontal direction. In this case, however, the gas flow 100 does not necessarily need to be supplied in the exact direction in the direction orthogonal to the tube axis of the connection pipe 16, but the gas flow 100 in the direction substantially orthogonal to the tube axis of the connection pipe 16. Supply it. Here, the direction orthogonal to the tube axis of the connecting pipe 16 is preferably in the range of ± 45 degrees, more preferably in the range of ± 25 degrees when the direction perpendicular to the tube axis is 0 degrees. It is more preferable that it is a range.

Moreover, in the aspect shown, the downstream connection pipe 16 was made into the gas flow lead-out pipe, and the upstream connection pipe 15 was made into the gas flow introduction pipe, but the upstream connection pipe 15 was made into the gas flow lead-out pipe. The downstream connection pipe 16 may be a gas flow introduction pipe. In this case, the 1st gas supply pipe which satisfy | fills said (1) and (2) in the relationship with the connection pipe 15 is formed.

Moreover, when the number of connection pipe | tubes is three or more, the arrangement | positioning of the connection pipe | tube which comprises a gas flow lead-out pipe, and the connection pipe | tube which constitutes a gas flow introduction pipe | tube can be selected suitably. For example, in the pressure reduction degassing apparatus shown in FIG. 1, when the 3rd connection tube is formed between the upstream connection pipe 15 and the downstream connection pipe 16, the relationship with the connection pipes 15 and 16 is shown. In the above, the first gas supply pipe that satisfies the above (1) and (2) may be formed, the connection pipes 15 and 16 may be gas flow lead-out pipes, and the third connection pipe may be a gas flow inlet pipe. Alternatively, a first gas supply pipe that satisfies the above (1) and (2) is formed in relation to the third connection pipe, and the third connection pipe is a gas flow lead-out pipe, and the connection pipes 15 and 16 are gasses. It may be a flow introduction tube.

In addition, the direction of the gas flow 120 which circulates through the atmosphere control part 14 and the pressure reduction degassing tank 11 is not limited to the aspect shown, The direction opposite to the aspect shown may be sufficient. For example, when the upstream connection pipe 15 is a gas flow derivation pipe and the downstream connection pipe 16 is a gas flow introduction pipe, the gas flows circulating through the atmosphere control unit 14 and the reduced pressure degassing tank 11. The direction of becomes opposite to the illustrated embodiment.

Moreover, in the aspect shown, although the positional relationship of two connection pipes is an upstream side and a downstream side, the positional relationship of a connection pipe is not limited to this. For example, you may make the positional relationship of two connection pipes into the front and inside of a figure. In this case, the direction of the gas flow circulating in the atmosphere control unit 14 and the reduced pressure degassing tank 11 is a direction orthogonal to the direction of the gas stream 120 in the illustrated embodiment (gas in the atmosphere control unit 14). The direction of the flow and the direction of the gas flow above the molten glass G in the pressure reduction degassing tank 11 become a figure front and an inside, or a figure inside and a front, respectively. In this case, the direction of the gas flow 120 in the pressure reduction degassing tank 11 becomes a direction orthogonal to the moving direction of the molten glass G. As shown in FIG. When the pressure reduction degassing tank 11 is elongate in the flow direction of the molten glass G as shown in the figure, the direction of the gas flow 120 above the molten glass G in the pressure reduction degassing tank 11 is Although it is preferable to remove the retention of the gas component from the molten glass G in the same direction or the opposite direction as the moving direction of the molten glass G, a pressure reduction degassing tank pays attention to the length in a horizontal-vertical direction. In the case where there is no difference (for example, the plane shape of the pressure reduction degassing tank is a square, a hexagon, an octagon, etc.), the direction of the gas flow 120 in the pressure reduction degassing tank 11 is a molten glass G Retention of the gas component from the molten glass G can be eliminated also in the direction orthogonal to the direction of movement of the sheet).

In the case where the pressure near the opening 18 generates a pressure difference in which the pressure is lower than that of the vacuum degassing tank 11, the component of the gas stream 100 supplied from the first gas supply pipe 20 is not particularly limited. Do not. However, it is preferable that the component of the gas stream 100 does not adversely affect the molten glass G, the glass goods manufactured, and glass manufacturing equipment, especially a vacuum degassing apparatus. Therefore, it is preferable that the component of the gas flow 100 does not contain corrosive and explosive gas.

In the case of using a low moisture gas having a water vapor concentration of 60 mol% or less as the gas stream 100 supplied from the first gas supply pipe 20, in addition to the effect of eliminating the retention of the gas component from the molten glass G, It is preferable at the point which the effect of reducing the water vapor | steam density | concentration of the atmosphere above molten-glass G inside the pressure reduction degassing tank 11 is anticipated.

The low moisture gas used as the gas stream 100 is not particularly limited as long as the water vapor concentration is 60 mol% or less. Specific examples of such low-moisture gas, air, dried air, N ₂ And an inert gas such as Ar. As the gas flow 100, one type of these low moisture gases may be used, or a mixed gas of plural types of low moisture gases may be used.

When using a low moisture gas as the gas stream 100, it is preferable that it is 50 mol% or less of a vapor concentration, It is more preferable that it is 40 mol% or less, It is further more preferable that it is 30 mol% or less, It is further more preferable that it is 25 mol% or less, It is more preferable that it is 20 mol% or less, It is more preferable that it is 15 mol% or less, It is further more preferable that it is 10 mol% or less, It is especially preferable that it is 5 mol% or less.

It is preferable that the water vapor concentration of the atmosphere above molten glass G in the pressure reduction degassing tank 11 is reduced to 60 mol% or less. By setting the water vapor concentration in the atmosphere to 60 mol% or less, it is possible to prevent the foam layer on the surface of the molten glass in the vacuum degassing tank from being enlarged and to generate dolby, thereby further improving the effect of vacuum degassing.

Moreover, since there exists a tendency for the foam layer of the molten glass surface to become thinner as the water vapor concentration of the atmosphere is low, it is preferable that the water vapor concentration of the atmosphere above the molten glass G in the pressure reduction degassing tank 11 is 50 mol% or less, It is more preferable that it is 40 mol% or less. And if a water vapor concentration is 30 mol% or less, since a cloth layer tends to become thinner, it is preferable.

Moreover, when the vapor concentration of the atmosphere is low, one bubble may shrink or break depending on the glass composition, and thus the fabric layer becomes thinner, which is preferable. Specifically, when the molten glass is borosilicate glass, if the water vapor concentration is 30 mol% or less, the bubbles tend to shrink significantly. In addition, the borosilicate glass said here is the following composition, for example.

Composition range: SiO ₂ : 55 ~ 74, Al ₂ O ₃ : 10 ~ 20, B ₂ O ₃ : 5 ~ 12, Al ₂ O ₃ / B ₂ O ₃ : 1.5 ~ 3, MgO: 0 ~ 5, CaO : 0-5, SrO: 0-12, BaO: 0-12, SrO + BaO: 6-12 (unit is mass%).

In addition, if the water vapor concentration of the atmosphere above the molten glass G in the pressure reduction degassing tank 11 is low, since the bubble of the magnitude | size enough to be regarded as a defect does not remain in the glassware manufactured through pressure reduction defoaming, it is preferable. Do. When the vapor concentration of the atmosphere is further lowered, the probability of defects occurring in the glass products produced through the reduced pressure defoaming is further lowered, more preferably 25 mol% or less, more preferably 20 mol% or less, and more preferably 15 mol% or less. It is more preferable, It is more preferable that it is 10 mol% or less, It is further more preferable that it is 5 mol% or less.

Moreover, volatilization of the specific component (boron etc.) in molten glass G can be suppressed by making the water vapor concentration of the atmosphere above molten glass G in the pressure reduction degassing tank 11 into 60 mol% or less. By suppressing the volatilization of components such as boron, it is possible to prevent the fluctuation of the composition of boron and the like, and to suppress the deterioration of the flatness caused by the composition fluctuation.

Moreover, since volatilization, such as other components which are liable to volatilize, for example, Cl, F, S, etc. can also be suppressed, the fluctuation | variation of the composition of these components can be prevented, and the deterioration of the flatness resulting from a composition fluctuation can be prevented. It can be suppressed.

It is thought that volatilization of these components, such as Cl, F, and S, is largely influenced by the moisture in atmosphere. For instance, F is an HF, S is considered to be volatilized as H ₂ SO _4. Therefore, it is thought that volatilization of the said component and the compositional fluctuation of the said component can be suppressed by making water vapor concentration of the atmosphere above the molten glass G inside the pressure reduction degassing tank 11 below a certain value.

Moreover, the characteristic of glass has the very detailed specification according to the use, and the composition of glass is decided in very detail so that it conforms to the specification. For example, although a standard exists naturally with respect to content of boron, in the conventional method, since boron was volatilized, it was necessary to use more boron as a raw material. In addition, conventionally, the amount of boron volatilized varies depending on conditions, and in some cases, there is a possibility that the boron content may be out of the specification of the content of boron. In the vacuum degassing apparatus of this invention, these problems can be solved by suppressing the volatilization of boron, and it is useful.

Also in this respect, the vacuum degassing apparatus of this invention is not called normal glass, and it can be said that it can use suitably especially when vacuum-defoaming a borosilicate glass.

It is preferable that the low moisture gas used as the gas flow 100 is a gas whose oxygen concentration is lower than the oxygen concentration in air. As for this oxygen concentration, it is more preferable that it is 15 volume% or less, It is more preferable that it is 10 volume% or less, It is more preferable that it is 5 volume% or less. In addition, low moisture gas, which is used as the gas stream 100, preferably containing no oxygen gas, for example, N ₂ gas, Ar gas, CO ₂ or the like.

Since the pressure reduction degassing tank 11 is a conduit of molten glass G, it is necessary to use the material excellent in heat resistance and corrosion resistance with respect to molten glass, and platinum or a platinum alloy is used widely. By using a gas having a lower oxygen concentration than the oxygen concentration in the air as the low moisture gas to be used as the gas stream 100, when platinum and a platinum alloy are used as the material of the vacuum degassing tank, the oxidation of the platinum is suppressed. Since the life of a pressure reduction degassing tank can be extended and the generation | occurrence | production of the defect derived from this platinum in glassware can be suppressed, it is preferable.

Specific examples of the platinum alloy include a platinum-gold alloy and a platinum-rhodium alloy. Moreover, the ceramic nonmetal inorganic material and dense refractory material are mentioned as another example of the material excellent in the heat resistance and corrosion resistance with respect to a molten glass used for a vacuum degassing tank. As a specific example of a dense refractory material, for example, electric pole refractory materials, such as an alumina pole refractories, a zirconia pole pole refractory, an alumina- zirconia-silica pole pole refractory, and a dense alumina base refractory, a dense zirconia-silica refractory body And dense calcined refractory materials such as dense alumina-zirconia-silica refractory materials.

In addition, in the vacuum degassing apparatus 10 shown in FIG. 1, similarly to the pressure reduction degassing tank 11, also as a material of the rising pipe 12 and the falling pipe 13 which comprise the conduit of molten glass G, platinum or Platinum alloys, or dense refractory, are used.

Since the atmosphere control part 14, the connection pipes 15 and 16, and the 1st gas supply pipe 20 are not the conduits of the molten glass G, the material is not specifically limited, For example, stainless steel, Metal materials, such as platinum and a platinum alloy, and fire-resistant and corrosion-resistant materials, such as ceramics and alumina, can be used.

In addition, in the vacuum degassing apparatus 10 of this invention, the objective of generating the gas flow 120 which circulates the atmosphere control part 14 and the pressure reduction degassing tank 11 is a thing of the gas component from molten glass G. Since the residence can be eliminated, it is not always necessary to generate the gas stream 120 during the degassing. Therefore, as long as the retention of the gas component from the molten glass G can be eliminated, the gas stream 120 may be periodically generated during the performance of reduced pressure defoaming, for example, 1 to 30 seconds per hour. The gas flow 120 may be generated at a ratio of about a degree. In addition, in order to generate | generate the gas flow 120 on a regular basis, what is necessary is just to supply the gas flow 100 from the 1st gas supply pipe 20 regularly.

In the vacuum degassing apparatus 10 of this invention, in order to reduce the water vapor | steam concentration of the atmosphere above the molten glass G in the vacuum degassing tank 11, in the upper space of the molten glass G in the vacuum degassing tank 11, You may form the 2nd gas supply line which supplies the low moisture gas 140 with water vapor concentration of 60 mol% or less.

It is sectional drawing which shows the other structural example of the vacuum degassing apparatus of this invention. In the pressure reduction degassing apparatus 10 'shown in FIG. 8, the 2nd gas supply pipe 24 is inserted from the connection pipe 15 which forms a gas flow introduction tube, and the front-end | tip of the 2nd gas supply pipe 24 is decompressed under pressure. It is located in the upper space of the molten glass G in the tank 11. In addition, about the specific example of the low moisture gas of 60 mol% or less of water vapor density | concentration supplied from the 2nd gas supply pipe 24, it is the same as that of what was described about the low moisture gas supplied as the gas stream 100. FIG.

In addition, the 2nd gas supply pipe should just be able to supply the low moisture gas of 60 mol% or less of water vapor concentration to the upper space of the molten glass G in the pressure reduction degassing tank 11, It is not limited to the aspect shown in FIG. For example, you may insert a 2nd gas supply pipe into the upper space of the molten glass G in the pressure reduction degassing tank 11 from the connection pipe 16 which comprises a gas flow lead-out pipe. Moreover, it is made in the upper space of the molten glass G in the pressure reduction degassing tank 11 from the cross section of the upstream or downstream side of parts other than the connection pipe 15 and 16, for example, the pressure reduction degassing tank 11. You may insert 2 gas supply lines. However, as shown in FIG. 8, the supply direction of the low moisture gas 140 is set to a direction in which the gas flow 120 (see FIG. 1) is not disturbed in the gas flow in the vacuum degassing tank 11. It is preferable at the point which does not generate | occur | produce.

Moreover, the outlet side position of the 2nd gas supply pipe 24 should just be able to supply the low moisture gas of 60 mol% or less of water vapor concentration to the upper space of the molten glass G in the pressure reduction degassing tank 11, and FIG. It is not limited to the aspect shown. For example, in the aspect shown in FIG. 8, although the front end of the 2nd gas supply pipe 24 is located in the upper space of the molten glass G in the pressure reduction degassing tank 11, the front end of the 2nd gas supply pipe 24 is carried out. It may exist in this connection pipe 15, and may be in the atmosphere control part 14 above the connection pipe 15. FIG.

The vacuum degassing apparatus of this invention may have a structure of that excepting the above. For example, in order to form the gas flow 120 near the surface (liquid surface) of the molten glass G, a baffle plate for guiding the gas flow 120 downward inside the ceiling of the vacuum degassing vessel 11 is provided. You may form.

The dimension of each component of the vacuum degassing apparatus 10 of this invention can be suitably selected as needed. The size of the pressure reduction degassing tank 11 is based on the shape of the pressure reduction degassing apparatus 11 and pressure reduction defoaming tank 11 used, regardless of whether the pressure reduction degassing tank 11 is a platinum agent, a platinum alloy agent, or a dense refractory agent. It can select accordingly. In the case of the cylindrical pressure reduction degassing tank 11 shown in FIG. 1, an example of the dimension is as follows.

Horizontal direction length: 1 to 20 m

Internal diameter: 0.2 to 3 m (cross section is round)

When the pressure reduction degassing tank 11 is a platinum agent or a platinum alloy agent, it is preferable that thickness is 4 mm or less, More preferably, it is 0.5-1.2 mm.

The vacuum degassing tank is not limited to a cylindrical shape having a circular cross section, and may be a substantially cylindrical shape having an elliptical shape or a semicircular shape, or a cylindrical shape having a rectangular cross section.

The rising pipe 12 and the falling pipe 13 can be appropriately selected depending on the vacuum degassing apparatus to be used, regardless of whether they are made of platinum, platinum alloy, or dense refractory. For example, in the case of the vacuum degassing apparatus 10 shown in FIG. 1, an example of the dimension of the rising pipe 12 and the downfalling pipe 13 is as follows.

Internal diameter: 0.05 to 0.8 m, more preferably 0.1 to 0.6 m

Length: 0.2-6 m, more preferably 0.4-4 m

In the case where the rising pipe 12 and the falling pipe 13 are made of platinum or a platinum alloy, the thickness is preferably 0.4 to 5 mm, more preferably 0.8 to 4 mm.

Although the dimension of the atmosphere control part 14 and the connection pipes 15 and 16 can be suitably made according to the vacuum degassing apparatus used, especially the vacuum degassing tank, the example is as follows.

Atmosphere control

Internal diameter: 0.1-3 m, more preferably 0.1-2 m

Length: 0.8 to 22 m, more preferably 1 to 20 m

Connector

Internal diameter: 0.05 to 0.5 m, more preferably 0.05 to 0.3 m

Length: 0.1-1 m, more preferably 0.1-0.8 m

First gas Supply pipe Bore

Internal diameter: 3-50 mm, more preferably 5-20 mm

Although the thickness of the atmosphere control part 14 and the connection pipes 15 and 16 differs also according to a structural material, when it is stainless steel, it is preferable that it is respectively the following.

Atmosphere control

0.5 to 2 mm, more preferably 0.5 to 1.5 mm

Connector

0.5 to 2 mm, more preferably 0.5 to 1.5 mm

Second gas Supply pipe Bore

Internal diameter: 3-50 mm, more preferably 5-20 mm

Example

Hereinafter, the present invention will be described in detail based on examples. However, the present invention is not limited to this.

In the Example, the venturi effect and the venturi effect by performing a gas flow analysis in the upper space of the molten glass G in a pressure reduction degassing tank using fluent, and supplying a gas flow from a 1st gas supply pipe to a virtual region. The release of the gas component retention from the molten glass by the atmosphere control part which generate | occur | produced by and the gas flow which circulates the upper space of the molten glass in a pressure reduction degassing tank was evaluated. In addition, as a vacuum degassing apparatus, the gas from the 1st gas supply pipe 20 to the virtual region 19 above the opening part 18 with the downstream connection pipe 16 like the vacuum degassing apparatus 10 shown in FIG. The stream 100 is supplied and the low moisture gas 140 is supplied from the second gas supply pipe 24 inserted into the upper space of the molten glass G in the vacuum degassing tank 11 from the upstream connection pipe 15. Was used as the model. Alternatively, unlike FIG. 8, the first gas supply pipe 20 is provided above the upstream connecting pipe 15 to supply the gas stream 100, and the reduced pressure degassing tank 11 is supplied from the downstream connecting pipe 16. Supplying the low moisture gas 140 from the 2nd gas supply pipe 24 inserted in the upper space of the inner molten glass G was used as a model. Moreover, gas stream 100 and the low-moisture gas 140 was modeled to be both for supplying N _2.

The dimension of each part of the vacuum degassing apparatus 10 used as a model is as follows.

Decompression degassing tank 11: total length 10 m, inner diameter 1 m (cross section is semi-circular shape)

Atmosphere control unit 14: total length 10 m, inner diameter 2 m (cylindrical shape)

Connection pipe (15, 16): 0.8 m in total length, 0.3 m in inner diameter (cylindrical shape)

The connecting pipes 15 and 16 are each positioned at a ceiling of the vacuum degassing tank 11, more specifically, at a position of 0.1 m from an upstream end of the vacuum degassing tank 11 and a position of 0.1 m from a downstream end. Formed.

Exhaust port 17: It was formed in the ceiling part of the position which becomes the center in the longitudinal direction of the inner diameter of 0.05m (cylindrical shape), and the atmosphere control part 14. As shown in FIG.

1st gas supply pipe 20: Unlike FIG. 8, the circular stainless steel nozzle of internal diameter (phi) 5 mm was inserted in the horizontal direction from the center of the downstream end of the atmosphere control part 14. As shown in FIG. In the case where the first gas supply pipe 20 is provided on either the downstream side or the upstream side, the position of the tip of the first gas supply pipe is 10 mm from the bottom of the atmosphere control unit 14 5 mm downstream from the opening 18. It was set as the position of mm.

Second gas supply pipe 24: A circular stainless steel nozzle having an inner diameter φ 15 mm from the ceiling of the atmosphere control unit 14 to the upper space of the molten glass G of the vacuum degassing tank 11 via the connecting pipe 15. Inserted. The position of the front end of the 2nd gas supply pipe was made into the position below 10 mm from the upper wall surface of the pressure reduction degassing tank 11.

The pressure in the upper space of the molten glass G in the pressure reduction degassing tank 11 and the inside of the atmosphere control part 14 were analyzed about the case where it is constant at 350 mmHg of pressure and 1400 degreeC of temperature.

In the analysis of the air flow, a transport model of unreacted species, a standard k-ε model, and a standard wall function were employed. Inlet diffusion and diffusion energy were not considered, and other setting parameters used default values. Analysis of the fluid flow property is used a value (to) of a mixture composed of N ₂ and H ₂ O in the volatilization Fluent database.

Viscosity: 1.72 × 10 ^-5 [kg / m · s]

Thermal Conductivity: 0.0454 [W / m · K]

Mass Diffusion Coefficient: 2.88 × 10 ^-5 [㎡ / s]

Density: ρ = pM _w / RT (incompressible gas equation)

Specific heat: c _p = ∑ _i Y _i c _p , _i (mass fraction average formula of specific heat by chemical species) [J / ㎏ · K]

From the vacuum degassing vessel 11, the molten glass (G) _{is, SO 3, O 2, B} 2 O 3, H 2 O or the like, but considered to be a plurality of gas is volatilized, in the analysis only for convenience H ₂ O 2.00 It is assumed to be volatilized at NL / min.

Hereinafter, in this specification, the gas volatilized from the molten glass G in the pressure reduction degassing tank 11 is simply called "volatility gas."

Movement of the molten glass (G) in the vacuum degassing vessel 11 is not considered, N ₂ supplied from the volatilized gases and the second gas supply pipe is defined according to the velocity boundary conditions.

In airflow analysis, as a density | concentration of the volatilization gas from the molten glass G in the pressure reduction degassing tank 11, the average density | concentration of the volatilization gas of molten glass G upper atmosphere (henceforth "the volatilization gas above molten glass G). May be referred to as the “average concentration of”). In addition, the volatilization gas density | concentration in the liquid surface vicinity (5 mm upward from the liquid level of molten glass) of molten glass G was made into the evaluation index.

Moreover, the pressure in the vicinity of the opening part of the atmosphere control part 14 and the connection pipe 15, and the pressure in the vicinity of the opening part 18 of the atmosphere control part 14 and the connection pipe 16 (henceforth, the former is "upstream opening pressure"). And the latter may be referred to as "downstream opening pressure".

Moreover, the amount of gas discharged | emitted from the pressure reduction degassing tank 11 to the atmosphere control part 14 through the connection pipe 15, and discharge | emitted from the pressure reduction degassing tank 11 to the atmosphere control part 14 via the connection pipe 16. FIG. The flow rate of the gas used (hereinafter, the former may be referred to as "upstream discharge flow rate" and the latter may be referred to as "downstream discharge flow rate") was evaluated.

(Examples 1, 2, 3, 4, 5, Comparative Example 1)

In Example 1, the above first to install a gas supply pipe 20 to the upper portion of the downstream-side connecting pipe 16 and supplying N ₂ as the gas stream 100 in the volume flow rate 2 NL / min, the molten glass (G) The average concentration of volatilized gas, the upstream opening pressure, the downstream opening pressure, the upstream discharge flow rate and the downstream discharge flow rate were evaluated.

In Example 2, the first gas supply pipe 20 to be installed on the upper portion of the downstream-side connecting pipe 16 and supplying N ₂ as the gas stream 100 in a volume flow rate 10 NL / min, the molten glass (G) above The average concentration of the volatilized gas, the upstream opening pressure, the downstream opening pressure, the upstream discharge flow rate, and the downstream discharge flow rate were evaluated.

Example 3, the first gas supply pipe 20 to be installed on the upper portion of the downstream-side connecting pipe 16 and supplying N ₂ as the gas stream 100 in a volume flow rate 15 NL / min, the molten glass (G) above The average concentration of the volatilized gas, the upstream opening pressure, the downstream opening pressure, the upstream discharge flow rate, and the downstream discharge flow rate were evaluated.

In Example 4, the first gas supply pipe 20 to be installed on the upper portion of the downstream-side connecting pipe 16 and supplying N ₂ as the gas stream 100 in a volume flow rate 50 NL / min, the molten glass (G) above The average concentration of the volatilized gas, the upstream opening pressure, the downstream opening pressure, the upstream discharge flow rate, and the downstream discharge flow rate were evaluated.

Example 5 In the first gas supply pipe 20 to be installed on the upper portion of the upstream-side connection pipe (15) and supplying N ₂ as the gas stream 100 in a volume flow rate 15 NL / min, the molten glass (G) above The average concentration of the volatilized gas, the upstream opening pressure, the downstream opening pressure, the upstream discharge flow rate, and the downstream discharge flow rate were evaluated.

In Example 6, to the first gas supply pipe 20 having an inner diameter of φ20 ㎜, installed on the upper portion of the downstream-side connecting pipe 15 and supplying N ₂ as the gas stream 100 in a volume flow rate 50 NL / min, the melt The average concentration of the volatilized gas above glass (G), the upstream opening pressure, the downstream opening pressure, the upstream discharge flow rate, and the downstream discharge flow rate were evaluated.

Example 7, an inner diameter of the first N ₂ gas supply line 20, the inner diameter installed in an upper portion of the upstream-side connecting pipe 15 of φ0.2 m, and a gas stream 100, the volume flow rate of φ5 ㎜ 2 NL / It supplied by min, and evaluated the average density | concentration of the volatilization gas above molten glass G, the upstream opening pressure, the downstream opening pressure, the upstream discharge flow volume, and the downstream discharge flow volume.

In Comparative Example 1, the average concentration of the volatilized gas above the molten glass G, the upstream side opening pressure, the downstream side opening pressure, and the upstream side discharge flow rate are not supplied from the first gas supply pipe 20. And downstream discharge flow rates.

In addition, the average concentration of the volatilization gas above the molten glass G in Examples 1-7 was shown as the relative value at the time of making the average concentration of the volatilization gas in the comparative example 1 100. In addition, the value of the upstream opening pressure (kPa) and the downstream opening pressure (kPa) was shown by the difference with the reference pressure (46,662 Pa = 350 mmHg) in the pressure reduction degassing tank 11. As shown in FIG. Moreover, the pressure difference between the upstream opening pressure (i) and the downstream opening (opening pressure (i) not having the first gas supply pipe 20)-opening pressure at the side having the first gas supply pipe (20). Iii)).

The results are shown in Table 1 below. In addition, the result of Examples 1-7 is a value in the time point which reached the steady state after supply of the gas stream 100 starts.

(Examples 8 to 13, Comparative Example 2)

Embodiment 8, the first gas supply pipe 20 for installation in the upper part of the downstream-side connecting pipe 16 and supplying N ₂ as the gas stream 100 in the volume flow rate 5 NL / min, and the second gas supply pipe (24 ) was installed at the top of the upstream-side connection pipe (15) and supplying N ₂ as low-moisture gas 140, the volume flow rate of 10 NL / min, the molten glass (G) the average concentration, the upstream-side opening portion of the volatilized gases in the upper The pressure, downstream opening pressure, upstream discharge flow rate and downstream discharge flow rate were evaluated.

Embodiment 9, the first gas supply pipe 20 for installation in the upper part of the downstream-side connecting pipe 16 and supplying N ₂ as the gas stream 100 in a volume flow rate 10 NL / min, and the second gas supply pipe (24 ) was installed at the top of the upstream-side connection pipe (15) and supplying N ₂ as low-moisture gas 140, the volume flow rate of 10 NL / min, the molten glass (G) the average concentration, the upstream-side opening portion of the volatilized gases in the upper The pressure, downstream opening pressure, upstream discharge flow rate and downstream discharge flow rate were evaluated.

Embodiment 10, the first gas supply pipe 20 for installation in the upper part of the downstream-side connecting pipe 16 and supplying N ₂ as the gas stream 100 in a volume flow rate 50 NL / min, and the second gas supply pipe (24 ) was installed at the top of the upstream-side connection pipe (15) and supplying N ₂ as low-moisture gas 140, the volume flow rate of 10 NL / min, the molten glass (G) the average concentration, the upstream-side opening portion of the volatilized gases in the upper The pressure, downstream opening pressure, upstream discharge flow rate and downstream discharge flow rate were evaluated.

Embodiment 11, the first gas supply pipe 20 for installation in the upper part of the upstream-side connection pipe (15) and supplying N ₂ as the gas stream 100 in a volume flow rate 10 NL / min, and the second gas supply pipe (24 ) Is installed in the upper portion of the downstream connection pipe 16 and N ₂ is supplied as a low moisture gas 140 at a volume flow rate of 10 NL / min, and the average concentration of volatilized gas above the molten glass G and the upstream opening The pressure, downstream opening pressure, upstream discharge flow rate and downstream discharge flow rate were evaluated.

In Example 12, an inner diameter of installation of the first gas supply pipe 20 in the φ20 ㎜, the upper part of the upstream-side connection pipe (15) and supplying N ₂ as the gas stream 100 in a volume flow rate 50 NL / min, and the 2 gas supply pipe 24 is installed on the upper side of the downstream connection pipe 16 and N ₂ is used as the low moisture gas 140. It supplied by the volume flow volume 15 NL / min, and evaluated the average density | concentration of the volatilization gas above molten glass G, the upstream opening pressure, the downstream opening pressure, the upstream discharge flow volume, and the downstream discharge flow volume.

In Example 13, the first gas supply pipe 20 having an inner diameter φ 5 mm was provided above the upstream connecting pipe 15 having an inner diameter φ 0.2 m, and N ₂ was used as the gas flow volume 100 NL /. supplying a min, and the second installation the gas supply pipe 24 to the upper portion of the downstream-side connecting pipe 16 and supplying N ₂ as low-moisture gas 140, the volume flow rate of 10 NL / min, the molten glass (G) The average concentration of the upstream volatilization gas, the upstream opening pressure, the downstream opening pressure, the upstream discharge flow rate and the downstream discharge flow rate were evaluated.

In Comparative Example 2, the first gas supply pipe 20 is not provided, the second gas to N ₂ by volume a supply pipe 24 provided at an upper part of the upstream-side connection pipe 15 and as a low water-gas 140 flow rate of 15 It supplied at NL / min, and evaluated the average density | concentration of the volatilization gas above molten glass G, the upstream opening pressure, the downstream opening pressure, the upstream discharge flow volume, and the downstream discharge flow volume.

In addition, the average concentration of the volatilization gas above the molten glass G in Examples 8-13 was shown as the relative value at the time of making the average concentration of the volatilization gas in the comparative example 1 100. In addition, the value of the upstream opening pressure (kPa) and the downstream opening pressure (kPa) was shown by the difference with the reference pressure (46,662 Pa = 350 mmHg) in the pressure reduction degassing tank 11. As shown in FIG. Moreover, the pressure difference (upstream opening pressure (K)-downstream opening pressure (K)) of an upstream opening pressure (i) and a downstream opening part was also shown.

The results are shown in Table 2 below. In addition, the result of Examples 8-13 is the value at the time of reaching a steady state after supply of the gas stream 100 starts.

Industrial availability

INDUSTRIAL APPLICABILITY The present invention can be used for production of various glass products of high quality containing no air bubbles, and is particularly preferable for vacuum degassing of borosilicate glass.

In addition, all the content of the JP Patent application 2008-50110, a claim, drawing, and the abstract for which it applied on February 29, 2008 is referred here, and it introduces as an indication of the specification of this invention.

10, 10 ': vacuum degassing apparatus
11: vacuum degassing tank
12: riser
13 down pipe
14: atmosphere control unit
15, 16: connection tube
17: exhaust port
18: opening
19: virtual area
20: first gas supply pipe
21: virtual line
24: second gas supply pipe
100, 120: gas flow
140: low moisture gas
200: dissolution tank
220: upstream feet
240: downstream feet
G: molten glass

Claims (5)

The internal air pressure is set below atmospheric pressure, connected to the vacuum degassing tank which floats and blows bubbles in the supplied molten glass, and the said vacuum degassing tank, and suction-raises the molten glass before a defoaming process, and introduces into the vacuum degassing tank. In the vacuum degassing apparatus of the molten glass which is connected to a riser and the said pressure reduction degassing tank, and has the falling pipe which descends and pulls out the molten glass after a defoaming process from the pressure reduction degassing tank,
The atmosphere control part of the hollow structure connected with the said pressure reduction degassing tank by at least 2 connection pipe | tubes, The atmosphere control part is provided with the exhaust port for evacuating and decompressing the inside of the atmosphere control part, At least 1 said The 1st gas supply pipe | tube which satisfy | fills following (1) and (2) in the relationship with the said connection pipe is formed, The pressure reduction defoaming apparatus of the molten glass characterized by the above-mentioned.
(1) The gas flow supplied from the said 1st gas supply pipe traverses the virtual area which extended the opening part which the said atmosphere control part and the said connection pipe extends inside the said atmosphere control part along the tube axis direction of the said connection pipe.
(2) An imaginary line extending from the distal end of the first gas supply pipe along the tube axis of the gas supply pipe does not pass through the opening formed by the atmosphere control unit and the connection pipe. The method of claim 1,
When the number of the connection pipes is X, the number of the first gas supply pipes is X-1 or less (however, the number of the first gas supply pipes is 1 or more). 3. The method according to claim 1 or 2,
The gas flow supplied from a said 1st gas supply pipe is a low moisture gas flow of 60 mol% or less of steam concentration, The vacuum degassing apparatus of the molten glass characterized by the above-mentioned. 3. The method according to claim 1 or 2,
A second gas supply pipe for supplying a low moisture gas having a vapor concentration of 60 mol% or less is further formed in an upper space of the molten glass in the vacuum degassing tank, characterized in that the vacuum degassing apparatus for molten glass. The pressure reduction defoaming method of the molten glass using the vacuum degassing apparatus of Claim 1 or 2, The pressure reduction defoaming method of the molten glass which supplies a gas flow from a said 1st gas supply line so that a following formula may be satisfied.
v> A / 0.031 × [5.487 × 10 ^-6 × (1 / 56.353-1 / ρ) + 19.6 × (0.163-z) +7.5 ² ] ^1/2
v: flow rate of the gas flow in the first gas supply pipe (m / s)
ρ: density of gas flow in the first gas supply pipe (kg / ㎥)
z: height (m) of the outlet portion of the first gas supply pipe in the atmosphere control unit
A: area of the opening (m 2)

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