Glass manufacturing apparatus and glass manufacturing method

Abstract

To provide a glass manufacturing apparatus capable of easily grasping the state of foreign particles in a gas supply pipe.SOLUTION: A glass manufacturing apparatus includes a forming device that forms a glass ribbon from molten glass, a gas supply pipe that supplies gas to the forming device, and a particle counter that is connected to the gas supply pipe and measures foreign particles in the gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a glass manufacturing apparatus and a glass manufacturing method. [Background technology]

[0002] A glass manufacturing apparatus for manufacturing flat glass includes a forming device that forms a glass ribbon from molten glass. In forming the glass ribbon, a predetermined gas may be supplied to the forming device to adjust the atmosphere in the vicinity of the molten glass and / or the glass ribbon.

[0003] For example, in a glass manufacturing apparatus using the float method, in order to prevent oxidation of the molten metal contained in the float bath, a reducing gas consisting of a mixture of nitrogen gas and hydrogen gas is supplied from a gas supply pipe to the atmosphere above the molten metal tank (e.g., Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2015-98425 [Patent Document 2] International Publication No. 2015 / 064595 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, glass manufacturing equipment may be shut down for purposes such as periodic maintenance. During the shutdown, foreign matter such as rust may form in the gas supply pipe. When the operation of the glass manufacturing equipment is resumed, such foreign matter may turn into particles and be carried to the forming device together with the supply gas, where it may fall onto the glass ribbon. The adhesion of such foreign matter particles to the glass may reduce the product yield.

[0006] Therefore, there is a need for effective measures to reduce the amount of foreign particles in the supply gas supplied to the molding machine. However, there has not been any means to directly measure foreign particles in the supply gas, and the information on foreign particles in the supply gas that is required to consider such measures is currently not accurately known. While it is possible to find an effective measure to reduce foreign particles by trial and error, this is not realistic in large-scale equipment such as a glass manufacturing apparatus, as it takes a long time to perform even one trial.

[0007] One aspect of the present disclosure provides a technology that can accurately grasp information about foreign particles in a supply gas supplied to a forming device in a glass manufacturing apparatus. [Means for solving the problem]

[0008] A glass manufacturing apparatus according to one aspect of the present disclosure includes a forming device that forms a glass ribbon from molten glass, a gas supply pipe that supplies gas to the forming device, and a particle counter that is connected to the gas supply pipe and that measures foreign particles in the gas. [Effects of the Invention]

[0009] According to one aspect of the present disclosure, information on foreign particles in a supply gas supplied to a molding apparatus can be accurately obtained. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating a portion of a glass manufacturing apparatus according to an embodiment. [Figure 2] FIG. 2 is an enlarged view of a portion I in FIG. [Figure 3] FIG. 1 is a flow diagram showing an example of the configuration of a particle counter system. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals, and descriptions thereof may be omitted.

[0012] A glass manufacturing apparatus according to an embodiment of the present disclosure is an apparatus for manufacturing sheet glass, and may include a melting apparatus, a forming apparatus, and an annealing apparatus. Fig. 1 mainly shows a forming apparatus 10 of the glass manufacturing apparatus 1 that forms a glass ribbon from molten glass.

[0013] In the melting apparatus, glass raw materials are melted to produce molten glass G. The resulting molten glass G is transported to a forming apparatus 10, where it is formed into a glass ribbon GR. The type of forming apparatus 10 is not particularly limited, and may be an apparatus used in a float method, a fusion method, a roll-out method, a down-draw method, a Colburn method, or the like. FIG. 1 shows a forming apparatus 10 using the float method as an example.

[0014] The flat glass produced by the glass manufacturing apparatus 1 may be, for example, alkali-free glass, aluminosilicate glass, borosilicate glass, soda-lime glass, etc. Alkali-free glass is glass that does not substantially contain alkali metal oxides such as Na2O and K2O. The use of the flat glass produced by the manufacturing apparatus 1 is not particularly limited, and the flat glass may be glass for vehicles such as automobiles, displays, etc. The thickness of the flat glass may be 0.1 mm to 12 mm depending on the use.

[0015] The forming apparatus 10 includes a forming furnace 11, which is a heat treatment furnace. As shown in FIG. 1 , the forming furnace 11 may include a molten metal tank 111 filled with molten metal M and an upper structure 112 disposed above the molten metal tank 111. The molten metal M is contained in the molten metal tank 111. As the molten metal M, for example, molten tin is used. The molten metal M may be any metal having a higher density than the molten glass G, and may be a molten tin alloy or the like. The molten glass G is continuously supplied onto the molten metal M from an inlet 11a of the molten metal tank 111, and is formed into a strip-shaped glass ribbon GR by utilizing the smooth liquid surface of the molten metal M.

[0016] Molten glass G transported from the melting apparatus is supplied from supply passage 15 to molten metal tank 111 via lip 15a. Tweel 15b is installed in supply passage 15 upstream of lip 15a so as to be able to move up and down, and the flow of molten glass G can be adjusted by this tweel 15b.

[0017] The glass ribbon GR formed on the molten metal tank 111 is drawn out by lift-out rolls 7 in a dross box section 6 connected downstream of the molten metal tank 111. The drawn glass ribbon GR is drawn into an annealing device, cooled, washed, and cut to a predetermined size to obtain float glass of a desired size.

[0018] A heater (not shown) for heating the glass ribbon GR may be provided inside the forming furnace 11. The heater may be, for example, an electric heater. Furthermore, a plurality of heaters may be suspended from the ceiling wall 112c of the upper structure 112 of the forming furnace 11 and arranged along the conveying direction of the glass ribbon GR. The heater can control the temperature distribution of the glass ribbon GR passing below it, and can control the thickness distribution of the glass ribbon GR.

[0019] In the forming apparatus 10 shown in FIG. 1, the inside of the forming furnace 11 is filled with a reducing gas to prevent oxidation of the molten metal M. The inside of the forming furnace 11 is maintained at a pressure higher than atmospheric pressure. The reducing gas may be, for example, a mixed gas containing nitrogen gas and hydrogen gas, preferably a mixed gas consisting of nitrogen gas and hydrogen gas. It is preferable that the mixed gas contains 85% by volume or more and 98.5% by volume or less of nitrogen gas and 1.5% by volume or more and 15% by volume or less of hydrogen gas. Such a gas can be supplied via a gas supply pipe 20, which will be described below.

[0020] As shown in Fig. 1, the glass manufacturing apparatus 1 includes a gas supply pipe 20 that supplies a gas (sometimes referred to as a supply gas) SG to the forming apparatus 10. The gas supply pipe 20 transports the gas SG supplied from a gas supply source 28, for example, a gas tank, and supplies it to the forming apparatus 10. The supply gas SG is supplied to an atmosphere near the molten glass G and / or the glass ribbon GR, or to an atmosphere in contact with the molten glass G and / or the glass ribbon GR. In the case of the glass manufacturing apparatus 1 using the float method shown in Fig. 1, the supply gas SG is supplied to an atmosphere above a molten metal tank 111 in the forming apparatus 10.

[0021] 1, the supply port of the gas supply pipe 20 is connected to an opening 112b formed in the ceiling wall 112c of the upper structure 112. As a result, the gas SG carried through the gas supply pipe 20 is supplied to the atmosphere above the molten metal tank 111 in the forming furnace 11 through the opening 112b. The connection position of the gas supply pipe 20 to the forming furnace 11 is not limited to the ceiling wall 112c of the upper structure 112, and may be a side surface of the upper structure 112.

[0022] When the glass manufacturing apparatus 1 is a float glass manufacturing apparatus, that is, when the forming apparatus 10 is a float glass forming apparatus, the supply gas SG supplied by the gas supply pipe 20 is, as described above, a reducing gas for preventing oxidation of the molten metal M. The gas in the gas supply pipe 20 is a compressed gas, and has a pressure higher than atmospheric pressure.

[0023] It should be noted that even when the glass manufacturing apparatus 1 is a glass manufacturing apparatus other than a float glass manufacturing apparatus, the supply gas SG is supplied to the atmosphere near the molten glass G and / or the glass ribbon GR. For example, in the case of a glass manufacturing apparatus using the fusion method, a predetermined gas can be supplied to the atmosphere near the molten glass and the glass ribbon in order to adjust the temperature and humidity of the glass ribbon GR, the surface tension of the molten glass G, and the like. In this case, the supply port of the gas supply pipe 20 can be arranged near the glass forming apparatus, or the gas supply pipe 20 can be connected to a chamber that houses the glass forming apparatus. In the case of a glass manufacturing apparatus using the fusion method, the gas supplied to the forming apparatus may be, for example, an inert gas such as nitrogen gas or argon gas, or air.

[0024] The glass manufacturing apparatus 1 may be shut down for a certain period of time for maintenance or the like. During this shutdown, foreign matter such as rust may be generated in the gas supply pipe 20. Such foreign matter may be generated by changes in the material of the gas supply pipe itself, or by changes in substances remaining in the gas supply pipe 20, or, if the gas supply pipe 20 has a welded portion, by changes in the welding material. The foreign matter may be, for example, metal, metal oxide, or the like. After the shutdown, when the glass manufacturing apparatus 1 is restarted and the supply gas SG is also flowed through the gas supply pipe 20, the foreign matter in the gas supply pipe 20 may become particulate, be carried by the supply gas SG flowing through the gas supply pipe 20, flow into the forming furnace 11, and fall onto the molten glass G and / or the glass ribbon GR. The foreign matter particles that fall and adhere to the glass ribbon may reduce the quality of the produced sheet glass, thereby reducing the yield.

[0025] Therefore, measures to reduce or remove foreign particles in the supply gas SG are required. Such measures include, for example, structural improvements such as the use of specific foreign particle collection means, such as filters or magnets, or process improvements such as purging at a specific pressure and for a specific time. Finding effective measures requires accurate information about the foreign particles in the supply gas, but such information has traditionally only been obtained by observing the foreign particles adhering to manufactured glass products. Until now, there has been no means for directly measuring foreign particles in the supply gas SG, and for example, the particle size and particle size frequency distribution (hereinafter referred to as particle size distribution) of foreign particles in the supply gas SG have not been accurately determined. It should be noted that measures to reduce or remove foreign particles in the supply gas SG can be considered to be investigated by trial and error. However, glass manufacturing equipment is a large-scale device that takes, for example, about a month or more just to start up the equipment, and even a single trial may take several months or more, so investigating measures by trial and error is not realistic.

[0026] In contrast, in one embodiment of the present disclosure, the glass manufacturing apparatus 1 is equipped with a particle counter 31 connected to the gas supply pipe 20. The provision of the particle counter 31 in the glass manufacturing apparatus 1 allows for direct counting of foreign particles in the supply gas SG flowing through the gas supply pipe 20. That is, it is possible to directly measure foreign particles suspended in the supply gas SG, rather than foreign particles attached to the final product, and therefore, the particle size distribution, etc. of the foreign particles can be obtained more accurately. Furthermore, temporal changes in the particle size distribution, etc. of the foreign particles can also be measured in real time. Thus, according to this embodiment, accurate information on the foreign particles in the supply gas SG can be obtained. The obtained information can be effectively used to consider measures for reducing or removing foreign particles, making it possible to find effective measures in a short period of time without trial and error.

[0027] Furthermore, in the configuration according to this embodiment, the supply gas SG flowing through the gas supply pipe 20 is sampled and measured, so that the foreign particle measurement can be performed while the glass manufacturing apparatus 1 is in operation. Therefore, if the foreign particle measurement is performed while the glass manufacturing apparatus 1 is in operation and the particle size distribution of the foreign particles changes due to some factor and the change is undesirable, it is possible to take corrective measures on the spot. Furthermore, the particle size distribution of the foreign particles may also change due to external factors such as environmental changes or impacts. Therefore, by measuring the state of the foreign particles in real time according to this embodiment, the measurement results can be used to detect external factors affecting the glass manufacturing apparatus 1 or to develop countermeasures against the external factors.

[0028] 1, particle counter (also referred to as particle counter main body) 31 is included in particle counter system 30 together with sampling pipe 32 that connects particle counter 31 to gas supply pipe 20. The tip of sampling pipe 32 may be disposed inside gas supply pipe 20. Sampling pipe 32 also has a gas intake section 35 (FIG. 2, described below) at its tip, and supply gas SG in gas supply pipe 20 is sucked in through gas intake section 35 and sent to particle counter 31 through sampling pipe 32.

[0029] The particle counter 31 may be, for example, a light scattering type device. The light scattering type involves forming a gas flow containing particles in a sensor section within the device, irradiating the gas flow with laser light, and reading the intensity of the scattered light as an electrical signal to determine the particle size. The particle counter 31 can measure the particle size distribution of foreign particles. Furthermore, based on the measured particle size distribution, it can also calculate distribution characteristics such as standard deviation, the average particle size of foreign particles, or the concentration of foreign particles, i.e., the number or volume of foreign particles per unit volume. The foreign particles may have a frequency distribution in the particle size range of 0.1 μm to 50 μm. The particle size may be the volume-equivalent diameter, and the average particle size may be the number-based median diameter.

[0030] Furthermore, it is preferable to use a particle counter compatible with pressurized gas as the particle counter 31. The term "compatible with pressurized gas" refers to the ability to detect particles in high-pressure gas such as compressed gas, i.e., gas at a pressure higher than atmospheric pressure. As described above, the supply gas SG in the gas supply pipe 20 is a high-pressure gas at a pressure higher than atmospheric pressure. More specifically, the pressure of the supply gas SG can be 0.1 MPa or more and 0.5 MPa or less. Therefore, in this embodiment, by using a particle counter compatible with pressurized gas, foreign particles in the supply gas SG in the gas supply pipe 20 can be measured more accurately. Note that the pressure of the supply gas SG may be measured near the connection point between the gas supply pipe 20 and the forming furnace 11.

[0031] A pressurized gas particle counter is, for example, a particle counter of a so-called self-compensating free jet type, in which the gas flow formed in the sensor section of the particle counter is formed by ejecting gas as a free jet from a nozzle without using sheath air, pressurized purging, etc. This type utilizes the ejector effect that entrains air around the gas flow, which is a free jet, and is less likely to lose balance with the pressure in the sensor section regardless of the pressure of the gas flow, thereby maintaining a stable gas flow. This allows for accurate detection of foreign particles in the supply gas SG in the gas supply pipe 20 in the glass manufacturing apparatus 1.

[0032] 1, the gas supply pipe 20 may include a main pipe 21 and a branch pipe 22 branching off from the main pipe 21. The branch pipe 22 may be a pipe extending from the outer circumferential surface of the main pipe 21, for example, extending in a direction substantially perpendicular to the axial direction of the main pipe 21. The tip of a sampling pipe 32 connected to a particle counter 31 may be disposed within the branch pipe 22. More specifically, a gas inlet 35 provided at the tip of the sampling pipe 32 may be disposed within the branch pipe 22. In this specification, the term "substantially perpendicular direction" refers not only to the strict perpendicular direction but also to a direction deviating from the strict perpendicular direction by approximately ±15°.

[0033] The inner diameter of branch pipe 22 is smaller than that of main pipe 21, and the flow rate of gas flowing through branch pipe 22 is also smaller than that of gas flowing through main pipe 21. By arranging gas inlet 35 in branch pipe 22 with a smaller diameter that branches off from main pipe 21 and sampling the gas to be measured by particle counter 31, a stable flow of sampled gas with reduced turbulence and vortices can be obtained, enabling more accurate measurement of foreign particles. Note that the inner diameter (Dm) of main pipe 21 may be 30 mm or more and 300 mm or less, and the inner diameter (Db) of branch pipe 22 may be 25 mm or more and 50 mm or less. Furthermore, the ratio (Db / Dm) of the inner diameter (Db) of branch pipe 22 to the inner diameter (Dm) of main pipe 21 may be 0.08 or more and 0.9 or less.

[0034] The gas supply pipe 20 may be configured not to have the branch pipe 22. In that case, the tip of the sampling pipe 32 may be configured to be disposed inside the main pipe 21, and gas sampling may be performed.

[0035] The position where the branch pipe 22 is formed in the main pipe 21 is not particularly limited, but it is preferably a position as close as possible to the connection position of the gas supply pipe 20 with the molding apparatus 10. For example, it is preferable that the branch pipe 22 be located closer to the connection position of the gas supply pipe 20 with the molding furnace 11 (the position of the opening 112b of the molding furnace 11) than to the gas supply source 28. Even if the branch pipe 22 is not provided, it is preferable that the particle counter system 30 be connected to the gas supply pipe 20 as close as possible to the connection position of the gas supply pipe 20 with the molding apparatus 10. This makes it possible to grasp the state of foreign particles in the gas immediately before it flows into the molding apparatus 10.

[0036] 2 shows an enlarged view of portion I in FIG. 1. As shown in FIG. 2, a gas inlet 35 provided at the tip of a sampling pipe 32 is disposed in a branch pipe 22 branching off from a main pipe 21 of a gas supply pipe 20. The configuration of the gas inlet 35 is not particularly limited, but the gas inlet 35 may be a tubular member having an inner diameter larger than that of the sampling pipe 32. This allows a volume of gas sufficient for measuring foreign particles to be collected and sent to the particle counter 31. Furthermore, because the inner diameter of the inlet 35 is smaller than that of the branch pipe 22, a gas flow rate lower than that of the gas in the branch pipe 22 can be sampled and sent to the particle counter 31, allowing measurement of foreign particles P based on a stable gas flow.

[0037] As shown in FIG. 2 , the gas inlet 35 may be provided so as to penetrate the peripheral wall of the branch pipe 22, approximately perpendicular to the axial direction of the branch pipe 22. The gas inlet 35 may be bent within the branch pipe 22 to have a proximal portion 351 that contacts the peripheral wall of the branch pipe 22 and a distal portion 352 that extends at a predetermined angle relative to the proximal portion 351. The distal portion 352 formed by bending the gas inlet 35 may have an axial direction that is aligned with the flow direction of the supply gas SG. This allows the flow direction of the gas flowing into the gas inlet 35 to be aligned with the flow direction of the supply gas SG (shown by the arrow in FIG. 2 ). The distal portion 352 may be positioned as close to the center of the branch pipe 22 as possible, preferably coaxially with the branch pipe 22. This allows gas to be sampled from a more stable gas flow with less turbulence and vortices at the center of the pipe, rather than from a position close to the peripheral wall of the pipe.

[0038] The suction unit 35 has an opening 35a at its tip, which serves as an inlet through which gas is drawn into the suction unit 35. The suction unit 35 can be arranged in the branch pipe 22 or the gas supply pipe 20 so that the opening 35a is located upstream of the gas flow. That is, the opening 35a of the suction unit 35 may be open to the upstream side of the gas flow. This allows the flow direction of the gas to be sampled to coincide with the flow direction of the supply gas SG in the gas supply pipe 20. That is, gas sampling can be performed without changing the flow direction of the gas to be sampled from the flow direction of the supply gas SG in the gas supply pipe 20. This allows a stable gas flow to be introduced into the sampling pipe 32 and the particle counter 31.

[0039] The above-described configuration of the gas inlet 35 is merely an example, and the gas inlet 35 may have a tubular shape without bending, with the inlet opening 35a formed on the circumferential surface of the tube. Also, the opening 35a of the gas inlet 35 may face downstream in the gas flow.

[0040] FIG. 3 shows an example of the configuration of a particle counter system 30 including a particle counter 31. FIG. 3 shows an outline of the flow in the particle counter system 30, with arrows in the figure indicating the flow of gas. The supply gas SG in, for example, the branch pipe 22 of the gas supply pipe 20 is sent to the particle counter 31 via the gas intake section 35 and the sampling pipe 32 described above. A regulator 36 capable of adjusting the pressure and / or flow rate to a constant value may be provided before, i.e., upstream of, the particle counter 31. Therefore, the presence of the regulator 36 makes it possible, for example, to keep the pressure of the gas flowing into the particle counter 31 constant, making the operation of the particle counter 31 more stable and improving the accuracy of foreign particle measurement.

[0041] In order to understand the state of the gas being sampled, the particle counter system 30 can also be provided with measuring instruments for measuring the pressure, flow rate, temperature, etc. in a separate flow branched off before the sampling pipe 32. For example, as shown in Fig. 3, by providing a pressure gauge 37 and a flow meter 38, the pressure and flow rate of the gas being sampled can be measured on the spot while foreign particles are being measured by the particle counter 31.

[0042] Furthermore, valves 39a and 39b, for example, can be provided in the flow path of particle counter system 30. When measurement of foreign particles by particle counter system 30 is not required, for example, valve 39b can be closed to prevent unnecessary gas from flowing into particle counter system 30.

[0043] Another embodiment of the present disclosure may be a glass manufacturing method for manufacturing a glass sheet using the above-described glass manufacturing apparatus. More specifically, the glass manufacturing method may be a glass manufacturing method using a glass manufacturing apparatus including a forming apparatus that forms a glass ribbon from molten glass, a gas supply pipe that supplies a gas to the forming apparatus, and a particle counter that is connected to the gas supply pipe and that measures foreign particles in the gas, the method including forming a glass ribbon from the molten glass while supplying gas from the gas supply pipe to the forming apparatus. Furthermore, the glass manufacturing method may include measuring foreign particles in the gas using the particle counter during or before forming a glass ribbon from the molten glass.

[0044] Although the present disclosure has been described above based on the embodiments, the present disclosure is not limited to these embodiments. Furthermore, the above embodiments can be subject to various changes, modifications, substitutions, additions, deletions, and combinations within the scope of the claims, and these also fall within the technical scope of the present invention. [Explanation of symbols]

[0045] 1. Glass manufacturing equipment 10 Molding equipment 11 Molding furnace 111 Molten metal bath 112 Superstructure 20 Gas supply pipe 21 Master 22 branch pipe 30 Particle Counter System 31 Particle Counter 32 Sampling tube 35 Gas intake section 35a opening 351 Proximal 352 Distal part G. Molten Glass GR Glass Ribbon P Foreign particles SG supply gas

Claims

1. a forming device for forming a glass ribbon from molten glass; a gas supply pipe for supplying gas to the molding device; a particle counter connected to the gas supply pipe and configured to measure foreign particles in the gas.

2. A sampling pipe having a gas intake port at its tip is connected to the particle counter, The glass manufacturing apparatus according to claim 1 , wherein the gas inlet is disposed in the gas supply pipe such that an opening at a tip of the gas inlet faces upstream in a flow of the gas.

3. the gas supply pipe includes a main pipe and a branch pipe connected to the main pipe and having an inner diameter smaller than that of the main pipe; The glass manufacturing apparatus according to claim 2 , wherein the gas suction section is disposed in the branch pipe.

4. 3. The glass manufacturing apparatus according to claim 1, wherein the particle counter is a light scattering type device that counts foreign particles in the gas by irradiating the free jet of the gas with light.

5. 3. The glass manufacturing apparatus according to claim 1, further comprising a regulator provided before an inlet of the particle counter, the regulator being capable of adjusting the pressure of the gas to a constant value.

6. the forming device has a molten metal tank containing molten metal, and molten glass is caused to flow over the molten metal to form a glass ribbon; 3. The glass manufacturing apparatus according to claim 1, wherein the gas supply pipe supplies a reducing gas to an atmosphere above the molten metal tank in the forming apparatus.

7. 6. The glass manufacturing apparatus according to claim 5, wherein the gas is a reducing gas comprising a mixture of nitrogen gas and hydrogen gas.

8. A glass manufacturing method using a glass manufacturing apparatus including: a forming device that forms a glass ribbon from molten glass; a gas supply pipe that supplies a gas to the forming device; and a particle counter that is connected to the gas supply pipe and that measures foreign particles in the gas, the method comprising: forming a glass ribbon from the molten glass while supplying gas from the gas supply pipe to the forming device.

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