JP2021031355A - Glass melting furnace and method for manufacturing glass - Google Patents

Abstract

To provide a glass melting furnace capable of monitoring reduction in electrical resistance properties of an electrocast brick or an insulating member in the inside of a melting tank, and a method for manufacturing glass.SOLUTION: A glass melting furnace 10 comprises: a melting tank 20 for supplying a glass raw material to the inside; a plurality of energization electrodes 30 provided so as to separate to each other in a plan view in the inside of the melting tank 20 and for energizing and melting the glass raw material to obtain molten glass; a detection electrode 40 provided in a region on the outer side of an energization region 200 energized by the energization electrode 30 in a plan view in the inside of the melting tank 20 without supplying electric power from the outside of the melting tank 20; and a voltage detector 50 for detecting the voltage of the detection electrode 40.SELECTED DRAWING: Figure 2

Description

The present invention relates to a glass melting furnace and a glass manufacturing method.

As one of the methods for melting the glass raw material, there is a method in which a pair of electrodes facing each other are inserted into the melting tank to energize the glass. When an AC voltage is applied between the electrodes to energize the glass, Joule heat is generated, so that the glass raw material is heated and the temperature rises, so that the glass raw material can be melted. Electric heating of the glass raw material is performed using a glass melting furnace having an electrode in the melting tank.

For example, Patent Document 1 discloses a glass melting furnace that melts a glass raw material by applying a voltage to a plurality of energizing electrodes provided at the bottom of a melting tank to energize the glass raw material.

Japanese Unexamined Patent Publication No. 7-300318

However, if the electrical resistance characteristics of the electroformed brick or the insulating member inside the melting tank deteriorate due to, for example, damage to the members inside the melting tank or deterioration of the members, the leakage current from the inside of the melting tank to the outside of the melting tank increases. The leakage current generates heat in the vicinity where the leakage current is generated, and erosion of the electroformed brick or the insulating member inside the melting tank is promoted. As a result, impurities mixed in the glass may increase. Therefore, it is required to understand the electrical resistance characteristics of the electroformed brick or the insulating member inside the melting tank.

An object of the present invention is to provide a glass melting furnace capable of grasping a decrease in electrical resistance characteristics of an electroformed brick or an insulating member inside a melting tank, and a glass manufacturing method.

The glass melting furnace according to one aspect of the present invention is provided inside the melting tank to which the glass raw material is supplied so as to be separated from each other in a plan view, and the glass raw material is energized to melt the glass raw material. , A plurality of energizing electrodes for obtaining molten glass, and a region outside the energizing region energized by the energizing electrode in a plan view inside the melting tank, for detection in which electric power is not supplied from the outside of the melting tank. It includes an electrode and a voltage detection unit that detects the voltage of the detection electrode.

The glass melting furnace and the glass manufacturing method of the present invention can grasp the decrease in the electrical resistance characteristics of the electroformed brick or the insulating member inside the melting tank.

It is a top view of the glass melting furnace in the 1st Embodiment which concerns on this invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. It is a flow chart which shows the manufacturing process of the glass in embodiment which concerns on this invention. It is a flow chart which shows the voltage detection process and comparison process in the melting process in embodiment which concerns on this invention. It is a graph which shows the time change of the voltage (ground potential) detected by the detection electrode in the embodiment which concerns on this invention. It is a flow chart which shows the voltage detection process and grounding switching process in the melting process in embodiment which concerns on this invention. It is a top view of the glass melting furnace in the 2nd Embodiment which concerns on this invention. FIG. 7 is a sectional view taken along line VIII-VIII in FIG.

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

"First embodiment"
The first embodiment of the glass melting furnace according to the present invention will be described with reference to FIGS. 1 and 2.

First, the structure of the glass melting furnace will be described.

As shown in FIGS. 1 and 2, the glass melting furnace 10 of the present embodiment includes a melting tank 20 in which a glass raw material is supplied, a plurality of energizing electrodes 30, a detection electrode 40, and a voltage detection unit 50. A normal ground electrode 60, a ground switching portion 70, and a superstructure 80 that covers the upper part of the melting tank 20 are provided. FIG. 1 shows a plan view of the glass melting furnace 10 through which the superstructure 80 is seen through.

The glass melting furnace 10 is provided with a burner (not shown) in the superstructure 80, and melts the glass raw material supplied to the inside of the melting tank 20 by burning the burner and applying a voltage to the energizing electrode 30. The melting tank 20 includes a bottom portion 21 and a side wall portion 22, and holds the molten glass G obtained by melting the glass raw material supplied to the inside. The melting tank 20 has a charging section 23 on the upstream side in the X-axis direction (right side in FIGS. 1 and 2) and an extraction section 24 on the downstream side in the X-axis direction (left side in FIGS. 1 and 2). In the melting tank 20, the glass raw material is charged from the charging unit 23, and the melted molten glass G is taken out from the extraction unit 24.

In the plan view of FIG. 1, the melting tank 20 is arranged along the inner wall 22a of the side wall portion 22 arranged along the flow direction (X-axis direction) of the molten glass G, and along the Y-axis direction perpendicular to the X-axis direction. A rectangular in-tank region 25 is formed by surrounding all sides with an inner wall 22a of the side wall portion 22 arranged therein. The in-tank region 25 forms a rectangle having a long side in the X-axis direction and a short side in the Y-axis direction in the plan view.

The bottom portion 21 or the side wall portion 22 includes an electroformed brick and an insulating member, and the electroformed brick may be provided inside the bottom portion 21 or the side wall portion 22 and an insulating member may be provided on the outside. Further, the bottom portion 21 or the side wall portion 22 may include an insulating member, and the bottom portion 21 or the side wall portion 22 may be provided with the insulating member inside and outside. The electroformed brick or insulating member prevents current from leaking from the bottom portion 21 and the side wall portion 22 to the outside of the melting tank 20. Compared to fired bricks, electroformed bricks have corrosion resistance to molten glass G melted at a high temperature, so that they are less likely to generate bubbles and gravel and are less likely to contaminate the melted molten glass G. .. Examples of the electroformed brick include AZS-based electroformed brick, zirconia-based electroformed brick, and alumina-based electroformed brick. As the insulating member, sintered bricks such as dense zircon bricks, zircon bricks, and mullite bricks are used. Further, as the insulating member, a refractory material having high electrical resistance such as hemisal or mica plate may be used.

Each energizing electrode 30 has a shape extending in the Z-axis direction and is arranged so as to penetrate the bottom portion 21. The tip of each current-carrying electrode 30 extends into the melting tank 20 so as to be inserted into the molten glass G. Each energizing electrode 30 is made of a conductor and is electrically insulated from the bottom 21 while being electrically conductive with the molten glass G. In the plan view of FIG. 1, three pairs of energizing electrodes 30 are arranged along the X-axis direction near each long side of the in-tank region 25, for a total of six pairs. Each pair of the energizing electrodes 30 is arranged so as to face each other in the X-axis direction. A power source 100 for applying an AC voltage is connected to each pair of the energizing electrodes 30 outside the melting tank 20. Since the AC voltage applied to the energizing electrode 30 is applied to the molten glass G through the energizing electrode 30, electricity flows through the molten glass G to generate Joule heat, and the molten glass G is heated.

The plurality of energizing electrodes 30 are provided inside the melting tank 20 so as to be separated from each other, and define the energizing region 200. As shown in FIG. 1, the energization region 200 is a region connecting adjacent electrodes and a common tangent. The energizing region 200 forms a rectangular energizing region 200 having a long side in the X-axis direction and a short side in the Y-axis direction in the plan view of FIG.

The detection electrode 40 has a shape extending in the Z-axis direction and is arranged so as to penetrate the bottom portion 21. The tip of the detection electrode 40 extends into the melting tank 20 so as to be inserted into the molten glass G. The detection electrode 40 is made of a conductor and is electrically insulated from the bottom portion 21 while being electrically insulated from the molten glass G.

Eight detection electrodes 40 are provided around the outer side of the energized region 200 and inside the side wall portion 22. In the plan view of FIG. 1, there are a total of eight detection electrodes 40, two on the upstream side of the energization region 200 in the X-axis direction and three on each long side of the tank region 25 along the X-axis direction. Be placed. As shown in FIG. 1, the three detection electrodes 40 and the three pairs of energizing electrodes 30 arranged along each long side are arranged at the same pitch with respect to the X-axis direction.

The positional relationship between the detection electrode 40 and the side wall portion 22 will be described. As shown in FIG. 1, when the distance between the end of the energization region 200 and the inner wall 22a of the side wall portion 22 is La, the detection electrode 40 is arranged at a position where the distance from the inner wall 22a of the side wall portion 22 is Lb. To. The detection electrode 40 is arranged at a position having a relationship of La> 2Lb, that is, at a position closer to the inner wall 22a than the end of the energization region 200. If the detection electrode 40 is arranged at the position, the change in the ground potential due to the deterioration of the electric resistance characteristic of the electroformed brick or the insulating member can be detected with high sensitivity without being affected by the energized region 200.

The detection electrode 40 is connected to the first end of the voltage detection unit 50 and the first end of the ground switching unit 70 outside the melting tank 20. On the other hand, outside the melting tank 20, the second end of the voltage detection unit 50 and the second end of the ground switching unit 70 are grounded. Therefore, since the detection electrode 40 is not supplied with electric power from the outside including the power source 100, the ground potential of the molten glass G can be detected.

The voltage detection unit 50 detects the ground potential of the detection electrode 40 by detecting the voltage between the first end and the second end of the voltage detection unit 50. In the present embodiment, the AC voltage synchronized with the power supply 100 is detected by the voltage detection unit 50, but even if the DC voltage, the AC voltage having a frequency different from that of the power supply 100, or the AC voltage having a phase different from that of the power supply 100 is detected. Often, the voltage to be detected may be selected in consideration of the magnitude of the detected voltage and the environmental noise. As will be described in detail later, the detection electrode 40 and the voltage detection unit 50 can monitor the deterioration of the electrical resistance characteristics of the electroformed brick or the insulating member inside the melting tank 20.

The ground switching unit 70 can manually or automatically switch the electrical connection state between the first end and the second end of the ground switching unit 70 itself. By switching the ground switching unit 70, the ground switching unit 70 can switch the potential of the detection electrode 40 to a non-grounded state or a grounded state. As the ground switching unit 70, a switch, a breaker, a variable resistor, or wiring with a clip can be applied. As will be described in detail later, the monitoring work and the maintenance work can be performed by switching to the non-grounded state or the grounded state by using the grounding switching unit 70.

Normally, the ground electrode 60 has a shape extending in the Z-axis direction and is arranged so as to penetrate the bottom portion 21. Normally, the ground electrode 60 is made of a conductor and is electrically insulated from the bottom 21 while being electrically insulated from the molten glass G. Normally, one ground electrode 60 is provided outside the energizing region 200 and inside the side wall portion 22. In the plan view of FIG. 1, one ground electrode 60 is usually arranged on the downstream side in the X-axis direction of the energization region 200. Outside the melting tank 20, the ground electrode 60 is usually always grounded. Normally, the ground electrode 60 lowers the ground potential on the downstream side in the X-axis direction to prevent electricity from flowing to the device downstream from the take-out portion 24.

The glass manufacturing method using the glass melting furnace 10 of the present embodiment will be described with reference to FIG.

The glass raw material is supplied into the melting tank 20 and the glass raw material is heated and melted (melting step: S1). The glass raw material is heated from above by radiating a flame of a burner (not shown) provided through the superstructure 80 toward the glass raw material. It is heated by the flame of a burner and is energized by applying a voltage to a plurality of energizing electrodes 30 to generate Joule heat and heat the glass raw material.

The molten glass G obtained by melting the glass raw material is molded in a molding furnace (not shown) provided downstream from the melting tank 20 (molding step: S2). The molded glass is slowly cooled in a slow cooling furnace (not shown) provided downstream of the molding furnace (slow cooling step: S3) to become a glass product.

The monitoring method and maintenance work inside the melting tank 20 in the glass melting furnace 10 of the present embodiment will be described in detail.

The monitoring method will be described with reference to FIG.
In the melting step S1, the voltage of each detection electrode 40 is detected (voltage detection step: S1a). Each ground switching unit 70 is set to a non-grounded state, and the voltage of each detection electrode 40 is detected by the voltage detection unit 50. Since each detection electrode 40 and the molten glass G are electrically conductive, the voltage detected by the voltage detection unit 50 corresponds to the ground potential of the molten glass G at the position where each detection electrode 40 is arranged. .. Therefore, by monitoring the voltage detection unit 50, the potential state of the molten glass G around the outside of the energized region 200 can be monitored.

Usually, the bottom portion 21 and the side wall portion 22 are electrically insulated from the molten glass G and the outside of the melting tank 20 by an electroformed brick or an insulating member. The molten glass G melted in the melting tank 20 by the insulation has a high ground potential. However, as the electrical resistance characteristics of the electroformed brick or the insulating member inside the bottom portion 21 and the side wall portion 22 continue to decrease, the leakage current flowing from the molten glass G to the outside of the melting tank 20 increases. When the leakage current toward the outside of the melting tank 20 increases, the ground potential of the molten glass G around the electroformed brick or the insulating member whose electrical resistance characteristics have deteriorated decreases. Therefore, if the voltage of each detection electrode 40 is monitored by the voltage detection unit 50, it is possible to monitor a decrease in the electrical resistance characteristics of the electroformed brick or the insulating member inside the bottom portion 21 and the side wall portion 22.

In the melting step S1, following the voltage detection step S1a, each voltage detected by the voltage detection unit 50 is compared (comparison step: S1b). In the case of the present embodiment, since the plurality of detection electrodes 40 are provided at different positions inside the melting tank 20, the ground potentials at different positions inside the melting tank 20 can be detected. By detecting the ground potentials at different positions, the ground potentials can be compared with each other, so that an abnormal ground potential can be detected and a position where the ground potential indicates an abnormality can be specified. If the position where the ground potential shows an abnormality can be specified, the electroformed brick or the insulating member having reduced electrical resistance characteristics can be specified.

Of the voltages detected by the eight detection electrodes 40, the voltage detected by the two detection electrodes 40 arranged on the upstream side in the X-axis direction of the energization region 200 is detected as compared with the other positions. The voltage is high. Therefore, the voltage detected by the two detection electrodes 40 can more sensitively monitor the decrease in the electrical resistance characteristics of the electroformed brick or the insulating member.

FIG. 5 shows an example of the ground potential waveform of the detection electrode 40 monitored by the voltage detection unit 50, and the horizontal axis shows the monitoring time and the vertical axis shows the voltage (ground potential) detected by the voltage detection unit 50. Is done. It can be seen that the normal ground potential Vo becomes a high value, but after the insulation deteriorates, the ground potential decreases and becomes a low value. Therefore, if the threshold value Vs is set to a value lower than the normal ground potential Vo, the detected ground potential is compared with the threshold value Vs, and it is detected that the ground potential is equal to or less than the threshold value Vs, electroforming is performed. It means that the moment when the insulation deterioration of the brick or the insulating member occurs is detected. For example, in the case of FIG. 5, the threshold value Vs is set to a value 15% lower than the normal ground potential Vo.

The maintenance work will be described with reference to FIG.
In the melting step S1, when the voltage of the detection electrode 40 is detected (voltage detection step: S1c) and the insulation deterioration of the electrocast brick or the insulating member is detected, it is connected to the detection electrode 40 at the position where the ground potential is lowered. The ground switching unit 70 is switched to the ground state, and the ground potential around the detection electrode 40 is set to the ground potential (ground switching step: S1d). If the ground potential is lowered to the ground potential, further erosion of the electroformed brick or the insulating member whose insulation has deteriorated can be suppressed. Further, if the ground potential is lowered to the ground potential, maintenance work under a high voltage can be avoided, and the side wall portion 22 can be easily repaired. When the maintenance work is performed, after the work is completed, the grounding switching unit 70 is switched to the non-grounded state, and the normal melting step is executed.

"Second embodiment"
A second embodiment of the glass melting furnace according to the present invention will be described with reference to FIGS. 7 and 8. Hereinafter, only the points different from the first embodiment will be described.

The glass melting furnace 10A of the present embodiment includes a plurality of energizing electrodes 31. In the plan view of FIG. 7, three current-carrying electrodes 31 are arranged on each long side of the in-tank region 25 along the X-axis direction, for a total of six. Each energizing electrode 31 has a plate shape in which the first plate surface 31a and the second plate surface 31b are a pair of plate surfaces. Each energizing electrode 31 is composed of a conductor. Each energizing electrode 31 is arranged inside the melting tank 20 so that the first plate surface 31a is aligned with the inner wall 22a of the side wall portion 22 of the melting tank 20. As shown in FIG. 7, the pair of energizing electrodes 31 arranged on each long side of the in-tank region 25 are arranged so that their second plate surfaces 31b face each other in the Y-axis direction. In FIG. 8, for convenience, the pair of energizing electrodes 31 are arranged so as to be offset from each other in the X-axis direction and the Z-axis direction. The pair of energizing electrodes 31 are arranged in three pairs along the X-axis direction. Each energizing electrode 31 is connected to the power supply 100 by a wiring leading from the inside of the melting tank 20 to the outside of the melting tank 20. The power supply 100 is connected to each pair of the energizing electrodes 31.

The plurality of energizing electrodes 31 are provided inside the melting tank 20 so as to be separated from each other in a plan view, and define the energizing region 201. A wide range of the melting tank 20 can be heated by energizing the energizing electrode 31 having this configuration. As shown in FIG. 7, the energization region 201 has a common tangent on the upstream side of the pair of energizing electrodes 31 that is the most upstream in the X-axis direction and a common tangent on the downstream side of the pair of energizing electrodes 31 that is the most downstream in the X-axis direction. And the area connecting the inner wall 22a of the side wall portion 22. The energized region 201 forms a rectangular energized region 201 in the plan view of FIG. 7.

In the plan view of FIG. 7, two detection electrodes 41 are arranged on the upstream side in the X-axis direction of the energization region 201.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the above embodiments, and design changes within a range not deviating from the gist of the present invention are also included.

In the present embodiment, the ground electrode 60 is usually installed, but if the electricity flowing to the device downstream from the take-out portion 24 does not matter, the ground electrode 60 may not be installed normally. Further, instead of the normal ground electrode 60, the detection electrodes 40 and 41 may be provided at the position of the normal ground electrode 60.

In the present embodiment, the glass raw material is melted by the burner heating and the electric heating, but the glass raw material may be melted by the electric heating alone.

In the present embodiment, the rectangular in-tank region 25 or the rectangular energizing regions 200 and 201 are configured in a plan view, but either the X-axis direction or the Y-axis direction may be the long side, and the side is square. You may. It may have a shape other than a rectangle.

In the present embodiment, a specific number or arrangement of the current-carrying electrode, the detection electrode, and the normal ground electrode has been described, but any number or arrangement may be used as long as the melting step can be performed.

The diameter of the detection electrode 40 may be made smaller if it is configured so as not to affect the melting process, or may be configured to be larger if a large amount of current is passed at the time of grounding.

In this embodiment, a mode in which different current-carrying electrodes are used in the first embodiment and the second embodiment has been described, but the current-carrying electrode 30 and the current-carrying electrode 31 may be installed in combination in one embodiment. The energizing electrodes 30 and 31 may be arranged in any combination as long as the space in the lower part or the side portion of the melting tank 20 can be effectively used.

In the present embodiment, the voltage detection unit 50 or the ground switching unit 70 is used, but it may be installed in the glass melting furnace 10 at all times or only when necessary.

The composition of the glass raw material used in the present embodiment is not particularly limited, and may be any of soda lime glass, non-alkali glass, mixed alkaline glass, borosilicate glass, or other glass. In addition, the manufactured glass products are used for construction, vehicles, flat panel displays, and various other uses.

10, 10A: Glass melting furnace 20: Melting tank 21: Bottom 22: Side wall 22a: Inner wall 23: Input section 24: Extraction section 25: Tank inner region 30: Energizing electrode 31: Energizing electrode 31a: First plate surface 31b : Second plate surface 40: Detection electrode 41: Detection electrode 50: Voltage detection unit 60: Normal ground electrode 70: Ground switching unit 80: Superstructure 100: Power supply 200: Energizing region 201: Energizing region G: Melting Glass

Claims (12)

A melting tank in which the glass raw material is supplied inside,
A plurality of energizing electrodes provided inside the melting tank so as to be separated from each other in a plan view and energize and melt the glass raw material to obtain molten glass.
A detection electrode provided in a region outside the energization region energized by the energization electrode in a plan view inside the dissolution tank, and power is not supplied from the outside of the dissolution tank.
A glass melting furnace including a voltage detection unit that detects the voltage of the detection electrode. The glass melting furnace according to claim 1, further comprising a grounding switching unit for switching the detection electrode between a non-grounded state and a grounded state. The melting tank is provided with an inner wall that forms a tank inner region in a plan view.
The glass melting furnace according to claim 1 or 2, wherein the detection electrode is installed at a position closer to the inner wall than the energized region in a plan view. The melting tank is provided with a charging portion on the inner wall into which the glass raw material is charged.
The glass melting furnace according to claim 3, wherein the detection electrode is installed at a position closer to the charging portion than the energized region. The glass melting furnace according to any one of claims 1 to 4, wherein a plurality of detection electrodes are provided at different positions from each other. The melting tank has a bottom and a side wall.
The glass melting furnace according to any one of claims 1 to 5, wherein the plurality of energizing electrodes are arranged on the bottom. The melting tank has a bottom and a side wall.
The glass melting furnace according to any one of claims 1 to 5, wherein the plurality of energizing electrodes are arranged on the side wall portion. The melting tank has a bottom and a side wall.
The glass melting furnace according to any one of claims 1 to 5, wherein the plurality of energizing electrodes are arranged on both the bottom portion and the side wall portion. The melting tank comprises a take-out portion for taking out the molten glass.
A normal grounding electrode that is always grounded is provided inside the melting tank.
The glass melting according to any one of claims 1 to 8, wherein the normal ground electrode is arranged in a region outside the energized region and closer to the take-out portion than the energized region in a plan view. Furnace. The glass manufacturing method using the glass melting furnace according to any one of claims 1 to 9.
A melting step of supplying the glass raw material to the melting tank and passing an electric current through the plurality of energizing electrodes to melt the glass raw material.
A molding step of molding the molten glass in a molding furnace provided downstream from the melting tank, and
Including a slow cooling step of slowly cooling the molded glass in a slow cooling furnace provided downstream of the molding furnace.
During the melting step,
A voltage detection step for detecting the voltage of the detection electrode and
Glass manufacturing method including. The glass manufacturing method according to claim 10, further comprising a grounding switching step of grounding the detection electrode when the detected voltage drops during the melting step. The glass manufacturing method according to claim 10 or 11, further comprising a comparison step of comparing each voltage detected by the voltage detection step during the melting step.

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