Patent Application
20170174546
The present invention relates to a glass melt production apparatus, a glass melt production method, a glass product production apparatus, and a glass product production method.
A glass plate to be used for buildings, for vehicles, for flat panel displays, etc., is produced by heating and melting a raw material prepared in a predetermined blend ratio in a melting vessel to obtain a glass melt, followed by refining the glass melt and forming it into a glass plate having a predetermined thickness e.g. by a float process, and cutting the obtained glass plate into a predetermined shape.
Refining is an operation to remove bubbles remaining in the glass melt to make the glass melt homogenous and is carried out to improve the quality of a glass plate to be produced. As a refining means, a vacuum degassing apparatus has been known, the interior of which is maintained at a predetermined degree of vacuum. In the vacuum degassing apparatus, bubbles in the glass melt continuously flowing therein are made to grow and to float up in the glass melt by employing their buoyancy, and are broken at the surface of the glass melt to be removed. Patent Document 1 discloses an example of such a vacuum degassing apparatus.
The vacuum degassing apparatus 1 shown in
Patent Document 1 discloses that the vacuum degassing vessel 12, the uprising pipe 13 and the downfalling pipe 14 forming the vacuum degassing apparatus 1 are made of a platinum alloy (platinum-rhodium alloy). When these constituent members are made of a refractory material (such as electro-cast bricks) less expensive than a noble metal, such as a platinum alloy, it is possible to make such constituent members large, for example, it is possible to increase their diameters such that a vacuum degassing apparatus with a large capacity can be built.
When the vacuum degassing apparatus 1 shown in
When the event of loss of depressurization causes the glass melt G to flow out from the inside of the vacuum degassing vessel 12, the liquid level of the glass melt G in each of the upstream pit 3 and the downstream pit 4 is elevated. In response to an elevation in the liquid level of the glass melt G, a part of the glass melt G in the upstream pit 3 moves upstream, i.e. toward the melting vessel 2 while a part of the glass melt G in the downstream pit 4 moves downstream, i.e. toward the successive treatment vessel (not shown).
The move of the glass melt G upstream from the upstream pit 3 causes little problem because the volume of the melting vessel 2 existing upstream is normally sufficiently large enough to accept such an elevation in the liquid level due to the move of the glass melt G.
On the other hand, the move of the glass melt G downstream from the downstream pit 4 normally cause no problem because the successive treatment vessel (not shown) is equipped with a drain-out system for draining an excessive part of the glass melt G. In a case where the downstream pit etc. has no drain-out system equipped therewith, or a case where the vacuum degassing vessel 12 is made large to build a large flow rate of vacuum degassing apparatus, the glass melt G flowing down from the inside of the vacuum degassing vessel 12, however, increases in the event of loss of depressurization. In such a case, the flow-down amount of the glass melt G could exceed the processing capacity of the drain-out system equipped with the successive treatment vessel (not shown) such that the glass melt G overflows. The occurrence of overflowing of the glass melt G in the successive treatment vessel (not shown) should be avoided because of possibly leading to the shutdown of glass product production equipment.
Patent Document 1: JP-A-2006-306662
Under these circumstances, it is an object of the present invention to reduce the influence caused by the flow-down of a glass melt from a vacuum degassing vessel in the event of loss of depressurization.
The present invention provides a glass melt production apparatus, which comprises a melting vessel, a vacuum degassing apparatus, a first conducting pipe structure connecting the melting vessel and the vacuum degassing apparatus, and a second conducting pipe structure to introduce a glass melt to a forming means, provided downstream the vacuum degassing apparatus;
the vacuum degassing apparatus having an uprising pipe through which the glass melt from the melting vessel ascends, a vacuum degassing vessel, and a downfalling pipe through which the glass melt from the vacuum degassing vessel descends;
the first conducting pipe structure having an upstream pit to supply the glass melt to the uprising pipe; and
the second conducting pipe structure having a downstream pit containing the glass melt from the downfalling pipe;
the glass melt production apparatus further comprising a third conducting pipe structure connecting the upstream pit and the downstream pit; and
the third conducting pipe structure having a closing means to shut off a flow of the glass melt in the third conducting pipe structure, the third conducting pipe structure or the closing means having a glass melt flow path for emergencies, which allows the glass melt to pass therethrough, depending on the height of a liquid level of the glass melt in the third conducting pipe structure in the vicinity of the closing means.
In the glass melt production apparatus according to one mode of the present invention, it is preferred that a glass melt flow path in each of the uprising pipe, the vacuum degassing vessel and the downfalling pipe be made of a refractory material.
In the glass melt production apparatus according to one mode of the present invention, it is preferred that the third conducting pipe structure be partly configured in a stepped structure in a direction of the flow of the glass melt to have a first glass melt flow path and a second glass melt flow path having different bottom heights, that the closing means be a plate-shape product insertable/removal into/from the first glass melt flow path of the third conducting pipe structure, that the plate-shape product have a planar shape formed in substantially the same as the cross sectional shape of the first glass melt flow path, and that the second glass melt flow path serve as the glass melt flow path for emergencies.
In the glass melt production apparatus according to one mode of the present invention, it is preferred that the closing means be a plate-shape product insertable/removal into/from the first glass melt flow path of the third conducting pipe structure, that the plate-shape product have a planar shape formed in substantially the same as the cross sectional shape of the first glass melt flow path, that the plate-shape product have an opening formed therein so as to serve as the glass melt flow path for emergencies.
In the glass melt production apparatus according to one mode of the present invention, it is preferred that the glass melt production apparatus further comprise a drain-out system in the third conducting pipe structure, which works, depending on the height of a liquid level of the glass melt in the third conducting pipe structure.
In the glass melt production apparatus according to one mode of the present invention, it is preferred that the vacuum degassing vessel be configured to be depressurized therein through a pipe by use of a vacuum pump, and that a shut-off valve be disposed in the pipe connecting the vacuum pump and the vacuum degassing vessel.
In the glass melt production apparatus according to one mode of the present invention, it is preferred that the vacuum degassing vessel be configured to be depressurized therein through a pipe by use of a vacuum pump, that a tank be disposed is disposed so as to be kept depressurized therein by driving the vacuum pump, and that a shut-off valve be disposed in a pipe connecting the tank and the vacuum degassing vessel.
Further, according to one mode of the present invention, there is provided a glass product production apparatus, which comprises the glass melt production apparatus of the present invention, a forming means to form the glass melt into a formed product, and an annealing means to anneal the formed product to obtain a glass product.
The present invention further provides a glass melt production method, which employs a glass melt production apparatus comprising a melting vessel, a vacuum degassing apparatus, a first conducting pipe structure connecting the melting vessel and the vacuum degassing apparatus, and a second conducting pipe structure to introduce a glass melt to a forming means, provided downstream the vacuum degassing apparatus;
the vacuum degassing apparatus having an uprising pipe through which the glass melt from the melting vessel ascends, a vacuum degassing vessel, and a downfalling pipe through which the glass melt from the vacuum degassing vessel descends;
the first conducting pipe structure having an upstream pit to supply the glass melt to the uprising pipe; and
the second conducting pipe structure having a downstream pit containing the glass melt from the downfalling pipe;
the glass melt production apparatus further including a third conducting pipe structure connecting the upstream pit and the downstream pit;
the third conducting pipe structure having a closing means to shut off a flow of the glass melt in the third conducting pipe structure; and the third conducting pipe structure or the closing means having a glass melt flow path for emergencies, which allows the glass melt to pass therethrough, depending on the height of a liquid level of the glass melt in the third conducting pipe structure in the vicinity of the closing means;
the glass melt production method comprising introducing the glass melt to the third conducting pipe structure when the glass melt flows down through the uprising pipe and the downfalling pipe by a decrease in the degree of depressurization in the vacuum degassing vessel during production of the glass melt, and performing flow control to reduce the move of the glass melt from the downstream pit further downstream beyond the downstream pit.
In one mode of the glass melt production method according to the present invention, it is preferred that the glass melt pass through a glass melt flow path for emergencies, depending on the height of a liquid level of the glass melt, to reduce the move of the glass melt.
Further, according to one mode of the glass melt production method according to the present invention, there is provided a glass product production method, which comprises a step of producing a glass melt by use of the glass melt production method according to the present invention, a step of forming the glass melt into a formed product, and a step of annealing the formed product to obtain a glass product.
In accordance with the glass melt production apparatus according to the present invention, in the event of loss of depressurization, it is possible to reduce the move of a glass melt downstream from the downstream pit by introducing the glass melt into the third conducting pipe structure out of use in normal operation of the glass melt production apparatus after the glass melt flows down from the vacuum degassing vessel into the downstream pit. Even if the glass melt moves downstream from the downstream pit in a large volume, it is possible to prevent the glass melt from overflowing in a case where the downstream pit etc. has no drain-out system equipped therewith, or a case where the flow-down amount of the glass melt exceeds the processing capacity of the drain-out system equipped with the successive treatment vessel (not shown in the drawings).
In accordance with the glass melt production apparatus according to the present invention, it is possible to open the glass melt flow path for emergencies for guiding the glass melt into the third conducing pipe structure, depending on the height of a liquid level of the glass melt in the vicinity of the closing means for shutting off the flow of the glass melt in the third conducting pipe structure.
Now, the present invention will be described with reference to drawings.
The glass melt production apparatus shown in
The glass melt G obtained in the melting vessel 100 shown in
The vacuum degassing apparatus 300 shown in
The vacuum housing 310 has a vacuum degassing vessel 320 accommodated therein so that its long axis is in a horizontal direction. The vacuum degassing vessel 320 has suction ports 321 and 322 formed in an upper part thereof to communicate with the vacuum housing 310 so as to reduce the pressure in the vacuum degassing vessel 320 and maintain the reduced pressure at a predetermined pressure by vacuum suction of the vacuum housing 310 by use of, e.g. a vacuum pump not shown.
The vacuum degassing vessel 320 has an uprising pipe 330 and a downfalling pipe 340 attached to a lower face of an end side thereof and a lower face of the other end side thereof, respectively, so as to vertically extend therefrom. The flow path of the glass melt G in each of the vacuum degassing vessel 320, the uprising pipe 330 and the downfalling pipe 340 is made of a refractory material.
The uprising pipe 330 has a lower end immersed in the glass melt G in an upstream pit 210 provided on a downstream end of the first conducting pipe structure 200 such that the glass melt G before degassing is drawn up from the upstream pit 210 to be introduced into the vacuum degassing vessel 320. The downfalling pipe 340 has a lower end immersed in the glass melt G in a downstream pit 410 provided on an upstream end of the second conducting pipe structure 400 such that the glass melt G after degassing is made to descend from the vacuum degassing vessel 320 to be introduced to the downstream pit 410.
The vacuum degassing apparatus 300 shown has extension tubes 350 and 360 attached to lower ends (lower leading ends) of the uprising pipe 330 and the downfalling pipe 340, respectively. The extension tubes 350 and 360 are hollow cylinders made of platinum or a platinum alloy, and such extension tubes 350 and 360 are respectively immersed in the glass melt G in the upstream pit 210 and the glass melt G in the downstream pit 410. However, in the vacuum degassing apparatus according to the present invention, the extension tubes attached to the lower ends of the uprising pipe and the downfalling pipe are optional constituents. The uprising pipe and the downfalling pipe may be made of a refractory material and be respectively immersed in the glass melt in the upstream pit and the glass melt G in the downstream pit.
The uprising pipe and the downfalling pipe per se may be hollow cylinders made of platinum or a platinum alloy. In a case where hollow cylinders made of platinum or a platinum alloy can be made large in diameter to build a large flow rate of vacuum degassing apparatus, when the glass melt production apparatus according to the present invention is not used, the glass melt G could overflow in the event of loss of depressurization.
The vacuum housing 310 has a heat-insulating material 390 disposed around each of the vacuum degassing vessel 320, the uprising pipe 330 and the downfalling pipe 340 therein.
The glass melt production apparatus shown in
The vacuum degassing apparatus 300 has closing means 510 and 520 disposed in the third conducting pipe structure 500 to shut off the flow of the glass melt G in the third conducting pipe structure 500 in normal operation. The closing means 510 and 520 are means for opening and closing the flow path of the glass melt G in the third conducting pipe structure 500 by arbitrary operation. In
Although the two closing means 510 and 520 are disposed in the third conducting pipe structure 500 in the vacuum degassing apparatus 300 shown in
The closing means may be disposed at any other position than the shown positions as long as it is possible to shut off the flow of the glass melt G in the third conducting pipe structure 500. For example, the closing means may be disposed at a more upstream position or downstream position in the third conducting pipe structure 500 than those shown in this Figure.
Specific structure of the closing means 510 and 520 will be described later on. When the event of loss of depressurization occurs in the vacuum degassing apparatus 300 shown in
For this purpose, the third conducting pipe structure 500 has a glass melt flow path for emergencies 540 disposed therein in the vicinity of the closing means 520 shown in
When the loss of depressurization occurs at the vacuum degassing apparatus 300 shown in
The third conducting pipe structure 500 also has a glass melt flow path for emergencies 530 disposed to pass the glass melt G therethrough, depending on the height of the liquid level of the glass melt G in the third conducting pipe structure 500 in the vicinity of the closing means 510. The glass melt flow path for emergencies 530 is measures to further guide the glass melt G to the upstream pit 210, the glass melt having been guided into the third conducting pipe structure 500 through the glass melt flow path for emergencies 540 disposed in the closing means 520. When a large amount of the glass melt G is introduced into the third conducting pipe structure 500 through the glass melt flow path for emergencies 540 disposed in the closing means 520, the glass melt G could overflow since the introduced amount of the glass melt exceeds the capacity of the third conducting pipe structure 500. In such a case, the glass melt G introduced into the third conducting pipe structure 500 is further introduced into the upstream pit 210 through the glass melt flow path for emergencies 530 disposed in the vicinity of the closing means 510 to prevent the glass melt G from overflowing in the third conducting pipe structure 500.
The glass melt G, which has been introduced into the third conducting pipe structure 500 through the glass melt flow path for emergencies 540, elevates the liquid level of the glass melt G in the third conducting pipe structure 500 in the vicinity of the closing means 510. When the height of the liquid level of the glass melt G reaches the certain height in the third conducting pipe structure 500 in the vicinity of the closing means 510, the glass melt G is allowed to pass through the glass melt flow path for emergencies 530 such that the glass melt G in the third conducting pipe structure 500 is introduced into the upstream pit 210.
Specific structures of the glass melt flow paths for emergencies 530 and 540 and the closing means 510 and 520 related thereto will be described below.
Although a portion of the third conducting pipe structure 500 with the closing means 510 disposed therein is shown in
As shown in
As shown in
As shown in
At the time of setting up the vacuum degassing apparatus 300, the operating member 511 is activated to draw the closing means 510 upward such that the first glass melt flow path 501 is opened in the third conducting pipe structure 500. Thus, the glass melt G is allowed to pass through the third conducting pipe structure 500 such that the glass melt G is supplied from the upstream pit 210 to the downstream pit 410.
In normal operation of the vacuum degassing apparatus 300, the operating member 511 is activated to insert the closing means 510 into the first glass melt flow path 501 of the third conducting pipe structure 500 from upward (the direction indicated by the arrow) such that the first glass melt flow path 501 is closed in the third conducting pipe structure 500. Thus, the flow of the glass melt G is shut off in the third conducting pipe structure 500.
In order to close the first glass melt flow path 501 in the third conducting pipe structure 500 by the closing means 510, the plate-shape product forming the closing means 510 has a planner shape preferably formed so as to be substantially the same as the cross sectional shape of the first glass melt flow path 501 in the third conducting pipe structure 200 as shown in
When the liquid level of the glass melt G is elevated in the vicinity of the closing means 510 in the third conducting pipe structure 500 such that the height of the liquid level of the glass melt G exceeds the height of the bottom surface of the second glass melt flow path 530 shown in
In the glass melt production apparatus according to the present invention, the glass melt flow path for emergencies in the third conducting pipe structure may have a different structure from that shown in
In
In
In
As stated earlier, when a large amount of the glass melt G is introduced into the third conducting pipe structure 500 through the glass melt flow path for emergencies 540 formed in the closing means 520, the introduced amount of the glass melt could exceed the capacity of the third conducting pipe structure 500 such that the glass melt G overflows. In order to prevent the glass melt G from overflowing in the third conducting pipe structure 500, it is preferred to dispose a drain-out system for the glass melt G in the third conducting pipe structure 500. Such a drain-out system is preferred to function, depending on the height of the liquid level of the glass melt G in the third conducting pipe structure 500. The drain-out system functioning according to the height of the liquid level of the glass melt G in the third conducting pipe structure 500 may be an opening formed in a side wall of the third conducting pipe structure 500 at a certain height, or such an opening with a glass melt flow path connected thereto for drain-out, for example.
As the drain-out system for the glass melt G introduced into the third conducting pipe structure 500, a manually operated drain-out system may be disposed in a side wall or a bottom of the third conducting pipe structure 500. The drain-out system is configured such that the opening formed in the side wall or bottom of the third conducting pipe structure 500 is kept plugged for emergencies while the opening is unplugged to drain-out the glass melt G in normal operation.
There are no particular limitations to the position to form the drain-out system and to the number of the drain-out systems formed in the third conducting pipe structure 500. These matters may be appropriately selected as needed. For example, the drain-out system may be disposed between the closing means 510 and the closing means 520, the drain-out system may be disposed upstream the closing means 510, or the drain-out system may be disposed downstream the closing means 520.
The features of the glass melt production apparatus according to the present invention, which reduces the influence caused by flow-down of a glass melt from a vacuum degassing vessel in event of loss of depressurization, has been described as above.
The glass melt production apparatus according to the present invention is preferred to further include a system for reducing an influence caused by loss of depressurization. The system for reducing an influence caused by loss of depressurization may be, for example, configured as follows:
As stated earlier, the vacuum degassing apparatus 300 shown in
When a tank is disposed in the pipe between the vacuum pump and the vacuum housing 310 to be kept in vacuum by driving the vacuum pump, the tank can be substituted for the vacuum pump to reduce the influence caused by the event of loss of depressurization in a case where a trouble is caused in the vacuum pump. When the tank is disposed in the pipe between the vacuum pump and the vacuum housing 310 to be kept in vacuum by driving the vacuum pump, it is preferred to dispose a shut-off valve of the pipe between the tank and the vacuum housing 310.
Now, the glass melt production method according to the present invention will be described.
The glass melt production method according to the present invention utilizes the glass melt production apparatus described above.
In the glass melt production method according to the present invention, the glass melt G flows into the upstream pit 210 from the melting vessel 100 through the first conducting pipe structure 200 with the inside of the vacuum degassing vessel 320 kept in a certain degree of depressurization, followed by being drawn up through the uprising pipe 330 into the vacuum degassing vessel 320. In the vacuum degassing vessel 320, the glass melt G is degassed. The glass melt G after degassing descends through the downfalling pipe 340 and is discharged into the downstream pit 410. In such a manner, high quality glass melt G with less bubbles can be obtained.
When the event of loss of depressurization occurs due to, e.g. a trouble in a vacuum pump such that the glass melt G in the vacuum degassing vessel 320 flows down into the downstream pit 410 through the downfalling pipe 340, the glass melt G flowing down into the downstream pit 410 is introduced into the third conducting pipe structure 500 through the glass melt flow path for emergencies 540 disposed in the vicinity of the closing means 520 in the third conducting pipe structure 500 or formed in the closing means. For example, it is possible to reduce the move of the glass melt by allowing the glass melt to pass through the glass melt flow path for emergencies, depending on the height of the liquid level of the glass melt flowing the glass melt flow path for emergencies. Thus, flow control is performed to reduce the move of the glass melt G from the downstream pit 410 further downstream beyond the downstream pit.
There is no limitation to the composition of the glass melt so long as the glass melt produced by the glass melt production method according to the present invention is a glass melt produced by a heat melting method. From this point of view, the glass melt may be soda lime glass or alkali-free glass, or may be mixed alkali glass, such as alkali borosilicate glass.
The amount of production of the glass melt is preferably from 100 to 1,000 ton/day, and considering a change in the type of the glass, incidental equipment etc., it is more preferably from 300 to 800 ton/day, further preferably from 350 to 700 ton/day.
Now, the glass product production apparatus according to the present invention will be described.
The glass product production apparatus according to the present invention comprises the above-described glass melt production apparatus according to the present invention, a forming means to form a glass melt into a formed product, and an annealing means to anneal the formed product to obtain a glass product. The forming means and the annealing means may be known ones. For example, as the forming means, an apparatus by a float process, a fusion process, a slot down process, a roll-form ing process, a roll-out process, a pull-up process or a down draw process may be mentioned. Among them, a forming means employing a float bath for the float process is preferred in that high quality plate glass having a wide range of thicknesses from thin plate glass to thick plate glass can be produced in a large amount. As the annealing means, for example, an annealing furnace equipped with a transport roll as a mechanism to transport glass after forming, and a mechanism to gradually reduce the temperature of the glass after forming is commonly employed. The mechanism to gradually reduce the temperature supplies a combustion gas or heat controlled by an electric heater to a necessary position in the furnace to gradually cool (that is, to anneal) the glass after forming. Thus, the residual stress inherent in the glass after forming can be eliminated.
The glass product production method according to the present invention comprises a step of producing a glass melt by the above-described glass melt production method according to the present invention (glass melt production step), a step of forming the glass melt into a formed product (forming step) and a step of annealing the glass after forming (annealing step).
In accordance with the glass melt production apparatus and the glass melt production method according to the present invention, in the event of loss of depressurization, it is possible to reduce the move of a glass melt downstream from the downstream pit by introducing the glass melt into the third conducting pipe structure out of use in normal operation of the glass melt production apparatus after the glass melt flows down from the vacuum degassing vessel into the downstream pit. Even if the glass melt moves downstream from the downstream pit in a large volume, it is possible to prevent the glass melt from overflowing in a case where the downstream pit etc. has no drain-out system equipped therewith, or a case where the flow-down amount of the glass melt exceeds the processing capacity of the drain-out system equipped with the successive treatment vessel.
In accordance with the glass melt production apparatus and the glass melt production method according to the present invention, it is possible to open the glass melt flow path for emergencies for introducing the glass melt into the third conducing pipe structure, depending on the height of a liquid level of the glass melt in the vicinity of the closing means for shutting off the flow of the glass melt in the third conducting pipe structure.
The glass melt production apparatus, the glass melt production method, the glass product production apparatus and the glass product production method according to the present invention are widely applicable to the production of glass for construction, glass for a vehicle, optical glass, glass for medical application, glass for a display and another general glass product.
This application is a continuation of PCT Application No. PCT/JP2015/077709, filed on Sep. 30, 2015, which is based upon and claims the benefit of priority from Japanese Patent Application No. 2014-201495 filed on Sep. 30, 2014. The contents of those applications are incorporated herein by reference in their entireties.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-201495 | Sep 2014 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2015/077709 | Sep 2015 | US |
| Child | 15449552 | US |
