JPH0333020A - Reduced-pressure defoaming device - Google Patents

Abstract

PURPOSE:To effectively prevent the buckling of the riser and downcomer for transferring a high temp. molten material in the reduced-pressure defoaming device for removing bubbles in a high-temp. molten material such as molten glass by providing a flexible seal member at a specified position. CONSTITUTION:The high-temp. molten material G in a melting tank 1 is introduced into a reduced-pressure defoaming tank 12 in a vacuum housing 11 through a riser 13 made of noble metal and defoamed. The defoamed material G is then transferred to a forming furnace 7 in the succeeding stage through a downcomer 14 made of noble metal. In this case, the gaps between the lower parts of the riser 13 and downcomer 14 and the lower ends of the casings 15 and 16 covering the riser 13 and downcomer 14 are closed by a flexible seal member 20 to control the deflection of the member 20 when the riser 13 and downcomer 14 are thermally expanded in the steady state. Consequently, even if the riser 13 and downcomer 14 are thermally expanded, the deformation due to thermal expansion is effectively absorbed by the member 20.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vacuum degassing device that removes air bubbles from high-temperature melts such as molten glass and molten metal, and particularly relates to a vacuum degassing device that removes air bubbles from high-temperature melts such as molten glass and molten metal. This invention relates to an improvement in a vacuum degassing device that is effective during the supply process.

[Conventional technology]

Conventionally, this type of decompression degassing equipment was developed by, for example,
There is one published in Publication No. 4205.

This is used in the process of degassing the molten glass G as a high-temperature melt in the melting tank 106 and continuously supplying it to the next processing furnace, as shown in FIG.
A vacuum degassing tank 1 is provided inside the vacuum housing 100 that is vacuum-suctioned.
A riser pipe 102 is connected to the reduced pressure degassing tank 101, through which molten glass G as a high-temperature melt before degassing treatment is introduced upward, and molten glass G after degassing treatment is connected to the vacuum degassing tank 101. downcomer pipe 103 where the material is led down to the next processing furnace
Casings 104 and 105 are connected to the vacuum housing 100, and casings 104 and 105 are thermally coated around each ascending pipe 102 and descending pipe 103.

Since the temperature of the rising pipe 102 and the descending pipe 103 is increased to 1,200 to 1,300° C. by the molten glass G, they are usually made of a noble metal such as platinum.

[Problem to be solved by the invention]

By the way, in this type of vacuum degassing device, the casings 104, 1 communicating with the vacuum housing 100 are
Since it is necessary to maintain the degree of reduced pressure inside the casing 100 by making the lower end of the casing 105 airtight, for example, the riser pipe 102 and the downcomer pipe 103 are connected to the lower end opening of each casing 105. It is necessary to hold the lower end periphery while keeping it airtight.

In this case, if the lower end peripheral portions of the riser pipe 102 and the downcomer pipe 103 that are connected to the vacuum degassing tank 100 are fixed to the lower end openings of each casing 104, 105, the molten glass G will be transferred to each riser pipe. 102 and the downcomer pipe 103, each of the riser pipe 102 and the downcomer pipe 103 thermally expands by about 50 to 60 mm, which inevitably results in buckling deformation of the riser pipe 102 and the downcomer pipe 103. creates technical challenges.

The present invention has been made in view of the above-mentioned technical problems, and it is an object of the present invention to provide a vacuum degassing device that can effectively avoid buckling deformation due to thermal expansion of an ascending pipe and a downcomer pipe.

[Means to solve the problem]

That is, the first invention provides a vacuum housing that is vacuum-suctioned, a vacuum degassing tank that is housed in the vacuum housing and forcefully defoams the high-temperature molten material, and a vacuum degassing tank that is connected in communication with the vacuum defoaming tank to degas the high-temperature melt. A rising pipe made of a precious metal that ascends and introduces the high-temperature molten material before foam treatment into the vacuum degassing tank, and a riser pipe that is connected to the vacuum degassing tank to descend the high-temperature molten material that has been defoamed in the vacuum degassing tank. A vacuum degassing device is provided which includes a downcomer pipe made of a noble metal to be led out, and a casing that is connected to the vacuum housing and covers the riser pipe and the downcomer pipe, and a portion near the lower end of the riser pipe and the downcomer pipe. and the lower end of the casing with a flexible sealing member to suppress the amount of change in deflection of the flexible sealing member in a steady state of thermal expansion of the ascending pipe and the descending pipe. .

Further, the second invention has the same basic configuration as the first invention, and includes a flexible seal member that closes the vicinity of the lower ends of the ascending pipe and the descending pipe and the lower ends of the respective casings. However, the present invention is characterized in that a pressure adjusting means is provided for pulling the flexible sealing member downward depending on the negative pressure state of the vacuum housing.

In such technical means, the degree of depressurization of the vacuum housing can be appropriately selected depending on the type of object to be degassed; for example, for molten glass, it is approximately 3.
0~100torr (-730~-660m+oHg)
It is preferable that the degree of

In addition, regarding the material of the vacuum degassing tank, the riser pipe, and the downcomer pipe, it is necessary to use at least precious metals such as platinum and molybdenum with a high melting point that do not melt in the target high-temperature melting material. The height and diameter of the pipe depend on the type of object to be degassed (temperature, viscosity), degassing process time,
It can be appropriately selected in consideration of processing amount and the like.

In particular, it is necessary to design the vacuum degassing tank, riser pipe, and downcomer pipe so that the temperature of the high-temperature molten material that passes through them does not drop. It is preferable to provide means such as arranging a vacuum degassing tank, the ascending pipe and the descending pipe directly with electricity, or heating them indirectly with a separate heater.

Furthermore, if the upper ends of the riser and downcomer pipes change due to temperature changes, the vacuum degassing conditions will change slightly, so the vacuum degassing tank and the upper ends of the riser and downcomer pipes should be fixedly connected. is preferred.

Furthermore, the flexible seal member maintains airtightness between the vicinity of the lower ends of the riser pipe and the downcomer pipe and the lower end of the casing, and absorbs the maximum amount of thermal expansion of the riser pipe and the downcomer pipe. As long as the material can be bent within a certain range, it can be appropriately selected such as a telescopic air bellows type or an elastic material that can be elastically deformed.

In addition, as a pressure adjustment means, the flexible sealing member is moved downward according to the degree of pressure reduction in the vacuum casing so that unnecessary stress is not applied to the rising pipe and downcomer pipe when the vacuum casing vacuum suction is activated. As long as it is tensile, the design may be changed as appropriate.

In this case, as a specific embodiment of the pressure regulating means, it may be constituted by a driving means such as an air cylinder that detects the degree of reduced pressure in the vacuum housing and is driven based on this detection signal; In order to naturally generate an offset force for the compressive force acting on the flexible seal member according to the degree of depressurization in the housing, the design can be changed as appropriate, such as by using a functional member such as an air bellows. From the viewpoint of simplification, it is preferable that the pressure adjustment means be constituted by a functional member such as an air bellows. Furthermore, from the viewpoint of effectively avoiding creep in the riser pipe and the downcomer pipe, it is preferable that the acting force of the pressure adjusting means be set to be slightly smaller than the compression acting force of the flexible seal member.

[Effect]

According to the above-mentioned technical means, the flexible sealing member maintains airtightness between the lower end portions of the rising pipe and the downcomer pipe and the lower end of each casing, and prevents the passage of high-temperature melt. absorbs thermal expansion changes in the riser and downcomer pipes.

In the first invention, since the amount of change in deflection of the flexible seal member is suppressed in the steady state of thermal expansion of the riser pipe and the downcomer pipe, even if the vacuum housing is operated by vacuum suction, the flexible seal member No unnecessary compressive stresses are created in the riser and downcomer pipes due to shrinkage of the members.

Further, in the second invention, the pressure regulating means applies a tensile force that cancels out the compressive force of the flexible seal member depending on the degree of pressure reduction in the vacuum housing. Even if the housing is operated by vacuum suction, no unnecessary external force is applied to the flexible sealing member, and unnecessary stress is not generated on the ascending pipe and the descending pipe.

Furthermore, since the flexible sealing member maintains its flexibility even during operation of the apparatus, even if the ascending pipe and the descending pipe are slightly expanded or contracted due to temperature changes during operation of the apparatus, the above-mentioned flexible seal member remains flexible. The sealing member is able to follow the deformation, and unnecessary stress is not generated in the ascending pipe and downcomer pipe during operation of the apparatus.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

Figures 1 and 2 show an example of a process in which molten glass is defoamed and continuously supplied to the next processing furnace.

In the figure, numeral 1 is a melting tank in which molten glass G is heated with a plate-shaped electrode 1a, and 2 is connected to the lower side wall of the melting tank 1, and molten glass G from the melting tank 1 is heated with a rod-shaped electrode 2a. A storage tank 3 connected to the guide duct 2 and temporarily storing the molten glass G;
Reference numeral 5 denotes a vacuum degassing device for defoaming the molten glass G stored in the storage tank 3 under reduced pressure conditions, and 5 indicates a molten glass that is connected in communication with the storage tank 3 and is defoamed in the vacuum degassing device 4. 6 is a partition plate that closes the communication state between the storage tank 3 and the guide duct 5 in normal times, and 7 is provided on the exit side of the guide duct 5 to prevent the melting after the degassing process. This is a molding furnace for molding glass G. Note that a heater (not shown) for heating the molten glass G is also provided in the guide duct 6.

In this embodiment, the vacuum degassing device 4 has a vacuum housing 11 made of stainless steel that is vacuum-suctioned by a vacuum pump 10, and a vacuum degassing tank 12 is disposed within the vacuum housing 11.

A riser pipe 13 made of platinum is fixedly connected to the bottom side of the vacuum degassing tank 12, and the lower end of the riser pipe 13 is connected to the molten glass G stored in the storage tank 3. It is designed to be immersed in water. On the other hand, on the other side of the bottom of the vacuum degassing tank 12, a downcomer pipe 1 also made of platinum is provided.
4 are fixedly connected in communication, and the lower end of this downcomer pipe 14 is immersed in the molten glass G in the guide duct 5. In addition, in the vacuum degassing device 4, the lower end of the downcomer 14 is positioned in the riser so that the molten glass G passes through the vacuum degather tank 12 from the riser 13 and then moves to the downcomer 14. It is set slightly lower than the lower end position of No. 13. The rising pipe 13 and the descending pipe 14 are electrically heated and maintained at a predetermined temperature based on a temperature control system not shown.

Furthermore, stainless steel casings 15 and 16 are disposed around the rising pipe 13 and the descending pipe 14, respectively.
The casings 15, 16 are connected in communication with the vacuum housing 11, and the lower end opening 15 of each casing 15, 16 is connected to the vacuum housing 11.
The lower ends of the rising pipe 13 and the descending pipe 14 are exposed to the outside from a and 16a. A heat insulating material 17 is provided inside the vacuum housing 11 and the casings 15 and 16 to cover the peripheries of the vacuum degassing tank 12, the rising pipe 13, and the descending pipe 14.

Furthermore, in this embodiment, a flexible sealing member 20 is provided between the vicinity of the lower ends of the riser pipe 13 and the downcomer pipe 14 exposed from the casing 15.16 and the lower end of the casing 15.16. There is.

This flexible sealing member 20, as particularly shown in FIG. 3, is constituted by an air bellows having flanges 22, 23 fixed to both ends of a stainless steel expandable bellows body 21. On the other hand, the rising pipe 13 and the descending pipe 1
A support flange 24 is provided protruding near the lower end of the support flange 4 . The flexible sealing member 20 is mounted on the upper side by fixing the flange 22 to the lower end of the casing 15.16 with a screw 26 via a seal packing 25, and the flexible sealing member 20 is mounted on the lower side. The flange 23 is connected to the support flange 24 with a screw 28 through a seal packing 27.
The rising pipe 13 is fixed to the support flange 24.
When mounting the downcomer pipe 14 with the insertion hole 29a, the bracket 29 is aligned with the screw 28.

Next, the operation of the vacuum degassing device according to this embodiment will be explained.

First, as a step before operating the vacuum degassing device, it is necessary to introduce the molten glass G into the vacuum defoaming device 4.

At this time, the rising pipe 13 and the descending pipe 14 are electrically heated in advance so that the molten glass G passes through the same conditions, while the partition plate 6 is once opened and the molten glass inside the storage tank 3 is heated. After introducing the glass G into the guide duct 5 side so that the lower ends of the rising pipe 13 and the descending pipe 14 are immersed in the molten glass G, the vacuum pump 10 may perform a vacuum suction operation. .

Then, the molten glass G rises through the ascending pipe 13 and the descending pipe 14 due to the negative pressure inside the vacuum housing 11,
After merging in the vacuum degassing tank 12, the molten glass G begins to move from the ascending pipe I3 toward the descending pipe 14 based on the siphon principle.

At this stage, when the partition plate 6 is closed and a predetermined period of time has elapsed, the molten glass G, which has been defoamed in the vacuum degassing tank 12 after ascending the riser pipe 13, is introduced into the guide duct 5 side through the downcomer pipe 14. Thereafter, the molten glass G that has passed through the vacuum degassing device 4 is continuously supplied to the next forming processing furnace 7 through the guide duct 5.

In such a vacuum degassing process, the riser pipe 13
When the molten glass G begins to pass through the rising pipe 14, the rising pipe 13 and the descending pipe 14 will thermally expand as shown by the imaginary lines, but the flexible sealing member 20 will close the rising pipe 13.
Since the deformation follows the thermal expansion deformation of the downcomer pipe 14, no unreasonable load is applied to the riser pipe 13 and the downcomer pipe 14, and the riser pipe 13 and the downcomer pipe 14 do not buckle.

Further, since the flexible sealing member 20 maintains airtightness between the lower end portions of the ascending pipe 13 and the descending pipe 14 and each of the casings 15 and 16, the degree of decompression within the vacuum housing 11 is maintained well. . Furthermore, when the rising pipe 13 and the descending pipe 14 reach a steady thermal expansion state (corresponding to the maximum thermal expansion state), the mounting can be carried out by fixing the bracket 29 to a predetermined fixed position. Since the flexible sealing member 20 does not contract or deform due to the negative pressure inside the housing 11, the rising pipe 13 and the descending pipe 14
No excessive compressive load will be applied to the

The basic configuration of the vacuum degassing device according to this example is Example 1
However, unlike Embodiment I, as shown in FIG. There is.

In this embodiment, the pressure adjusting means 40 includes a pressure sensor 41 that communicates with the vacuum housing 11 and detects the pressure inside the casing 15, for example, and adjusts the drive air pressure based on the pressure signal from the pressure sensor 41. A pressure controller 42 and a pair of air cylinders 43 attached to the lower end side of the flexible seal member 20 are provided on the bracket 29, respectively, and are driven based on drive air pressure from the pressure controller 42. . The tensile driving force of the pair of air cylinders 43 is the same as that of the vacuum housing 1.
The compressive force P acting on the flexible seal member 20 is set to completely cancel out the compressive force P acting on the flexible seal member 20 according to the degree of pressure reduction of 1.

Therefore, according to this embodiment, although the basic operation of the flexible seal member 20 is the same as in the first embodiment, the compressive force that acts on the flexible seal member 20 depending on the degree of pressure reduction in the vacuum housing 11 is Since P is equal to the driving force of the air cylinder 43, the bracket 29 can be maintained in an equilibrium state during the installation without having to specifically fix the bracket 29 to a fixed position.

Therefore, in addition to the fact that no unreasonable load is applied to the rising pipe 13 and the descending pipe 14 due to the vacuum suction operation,
Since the flexible sealing member 20 is kept flexible even during operation of the apparatus, even if the ascending pipe 13 and the descending pipe 14 thermally expand or contract due to temperature changes during the operation of the apparatus, the change will not occur. The stress is effectively absorbed by the flexible sealing member 20, so that stress caused by temperature changes does not act unnecessarily on the rising pipe 13 and the descending pipe 14.

In this embodiment, if the driving force of the air cylinder 43 is set to be slightly smaller than the compressive force P of the flexible seal member 20, the rising pipe 13 and the descending pipe 14
The compressive force P of the flexible sealing member 20 is canceled out in a state where a very slight compressive stress is applied to the pipe, thereby making it possible to extend the life of the ascending pipe 13 and the downcomer pipe 14 against the creep phenomenon.

The basic configuration of the vacuum degassing device according to this example is Example 2
The second embodiment is substantially the same as the second embodiment, but the pressure adjustment means 40 is different from the second embodiment.

In this embodiment, the pressure regulating means 40 is comprised of a pair of air bellows 50, as shown in FIG.

That is, the air bellows 50 is attached to both ends of a telescopic bellows body 51 made of stainless steel through flanges 52.
．． 53 is fixed to the casings 15 and 16 through a heat-resistant hose 54, and is connected to the casings 15 and 16 through a heat-resistant hose 54.
It is disposed on a pair of support pieces 55 that protrude from the sides of the lower ends of the shings 15 and 16.

On the other hand, when attaching to the flexible seal member 2, L-shaped connecting arms 56 are integrally formed at both ends of the bracket 29, and when attaching the air bellows 50 to the lower side, the flange 52 has a seal packing 57. The upper mounting flange 53 of the air bellows 50 is fixed to the horizontal portion of the connecting arm 56 with screws 60 via a seal packing 59.

The effective area A1 of both air bellows 50 is approximately equal to the effective area A of the air bellows, which is the flexible seal member 20.

Therefore, according to this embodiment, when the compressive force P acts on the effective area A of the flexible sealing member 20 according to the degree of decompression of the vacuum nozzle 11, the effective area A1/2 of each air bellows 50 is A tensile force PI/2 that corresponds to the degree of pressure reduction in the vacuum housing 11 is applied.

At this time, since the effective area A of the flexible sealing member 20 and the effective area Al of both air bellows 50 are approximately equal, the compressive force P acting on the flexible sealing member 20 and both air bellows 50 The tensile force Pl acting on the flexible sealing member 20 is approximately equal to the compressive force Pl acting on the flexible seal member 20.
will be canceled out by the air bellows 50.

Therefore, similarly to the second embodiment, the ascending pipe 13 and the descending pipe 1
4 is not subjected to an unreasonable load due to the vacuum suction operation, and the flexible sealing member 20 is able to flex and deform even during the operation of the device, so that the ascending pipe 13 and the descending pipe 14 are Even if there is thermal expansion or contraction due to temperature changes during operation, stress due to temperature changes will not act unnecessarily on the riser pipe 13 and the downcomer pipe 14.

In this embodiment, when the tensile force Pl of both air bellows 50 is set to be slightly smaller than the compressive force P of the flexible seal member 20, the effective area AI of both air bellows 50 is It is only necessary to make the area slightly smaller than the effective area A of the sealing member 20.

〔Effect of the invention〕

As explained above, according to the vacuum degassing device according to the present invention, a flexible seal member is used to close the vicinity of the lower ends of the ascending pipe and the downcomer pipe and the lower end of each casing, and the vacuum housing is closed. Since the flexible sealing member is prevented from shrinking and deforming during the vacuum suction operation, even if the rising pipe and downgoing pipe connected to the vacuum degassing tank thermally expand as the high-temperature molten material passes, The flexible seal member can effectively absorb the thermal expansion deformation described above, thereby effectively preventing buckling deformation of the ascending pipe and downcomer pipe sections, and also prevents buckling during the vacuum suction operation of the vacuum housing. , while reliably maintaining the reduced pressure of the vacuum housing, generation of excessive stress on the rising pipe and downcomer pipe can be eliminated, and buckling deformation of the rising pipe and downcomer pipe portions can also be effectively prevented.

Further, according to the vacuum degassing device according to any one of claims 2 to 4, even if the riser pipe and the downcomer pipe are slightly expanded or contracted due to temperature changes during operation of the device, the flexible seal member This prevents unnecessary stress from being generated in the ascending pipe and downcomer pipe, thereby effectively preventing the rising pipe and downcomer pipe from breaking due to thermal deformation during equipment operation. can.

In particular, according to the vacuum degassing device according to claim 3, the pressure regulating means is configured to apply a tensile force that is slightly smaller than the contraction force of the flexible seal member, so that the rising pipe and the descending pipe are The tube is balanced with very little compressive stress acting on it, and it is possible to effectively avoid tensile rupture or creep rupture that tends to occur when tensile stress is applied.

Furthermore, according to the vacuum degassing device according to claim 4, since the pressure adjustment means is constituted by the air bellows communicating with the vacuum housing, the pressure inside the vacuum/'% housing is detected and this detection is performed. The device configuration can be simplified compared to systems that control pressure based on signals.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional explanatory diagram showing a schematic configuration of Example 1 of the vacuum defoaming device according to the present invention, FIG. 2 is a perspective view showing an example of a process in which the vacuum defoaming device according to Example 1 is incorporated, and FIG. The figures are a detailed explanatory view of the part ■ in Fig. 1, Fig. 4 is an explanatory view similar to Fig. 3 showing Example 2 of the vacuum degassing device according to the present invention, and Fig. 5 is a vacuum defoaming device according to the present invention. FIG. 6 is an explanatory diagram similar to FIG. 3 showing a third embodiment of the apparatus, and FIG. 6 is an explanatory diagram showing a schematic configuration of a conventional vacuum degassing apparatus. [Explanation of symbols] 11... Vacuum housing 12... Decompression degassing tank 13... Ascending pipe 14... Descending pipe 15.16... Casing 20... Flexible sealing member 40...・Pressure adjustment means 50...air bellows

Claims (1)

[Claims] 1) A vacuum housing (11) that is vacuum-suctioned, and a high-temperature molten material (
A vacuum degassing tank (12) is connected to the vacuum defoaming tank (12) to degas G), and the high temperature molten material (G) before the defoaming process is transferred to the vacuum defoaming tank (12). A noble metal riser pipe (13) is connected to the vacuum degassing tank (12) and is connected to the vacuum defoaming tank (12).
A downcomer pipe (14) made of a precious metal for descending the high-temperature molten material (G) that has been degassed in step 12), and the ascent pipe (13) and the downcomer pipe that are connected in communication with the vacuum housing (11), respectively. (14) in a vacuum degassing device comprising a casing (15, 16) covering a casing (15, 16), the vicinity of the lower end of the rising pipe (13) and the descending pipe (14) and the lower end of each of the casings (15, 16). A flexible sealing member (20) is used to close the space between the rising pipe (13) and the descending pipe (14), and the amount of change in deflection of the flexible sealing member (20) is suppressed in a steady state of thermal expansion of the rising pipe (13) and the descending pipe (14). A vacuum degassing device characterized by: 2) A vacuum housing (11) that is vacuum-suctioned, and a high-temperature molten material (
A vacuum degassing tank (12) is connected to the vacuum defoaming tank (12) to degas G), and the high temperature molten material (G) before the defoaming process is transferred to the vacuum defoaming tank (12). A noble metal rising pipe (13) is connected to the vacuum degassing tank (12) and is connected to the vacuum defoaming tank (12).
A downcomer pipe (14) made of a precious metal for descending the high-temperature molten material (G) that has been degassed in step 12), and the ascent pipe (13) and the downcomer pipe that are connected in communication with the vacuum housing (11), respectively. (14) in a vacuum degassing device comprising a casing (15, 16) covering a casing (15, 16), the vicinity of the lower end of the rising pipe (13) and the descending pipe (14) and the lower end of each of the casings (15, 16). and a pressure adjusting means (20) for closing the space between the flexible sealing member (20) and pulling the flexible sealing member (20) downward according to the negative pressure state of the vacuum housing (11).
40) A vacuum degassing device characterized by being attached. 3) The device according to claim 2, wherein the pressure adjusting means (40) is configured to include the flexible sealing member (
20) A vacuum degassing device that is tensioned with a slightly smaller force than the contraction force of item 20). 4) In the device according to claim 2 or 3, the pressure regulating means (40) is configured to control the rising pipe (13) and the descending pipe (
14) A vacuum degassing device characterized in that it is composed of air bellows (50) communicating with the casings (15, 16) and canceling the force acting on the flexible sealing member (20). Device.