Remaining thickness measuring device, remaining thickness measuring method, and glass manufacturing method

Abstract

To provide a technology that measures residual thickness of a wall of a dissolving tank without stopping electric heating of molten glass.SOLUTION: A residual thickness measuring apparatus measures residual thickness of a wall of a dissolving tank for storing molten glass to be energized and heated. The residual thickness measuring apparatus includes: a metal scale inserted into a through-hole of the wall; and an insulation cover for covering at least partially an outer peripheral surface of the scale on an outside of the wall.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a residual thickness measuring device, a residual thickness measuring method, and a glass manufacturing method. [Background technology]

[0002] The melting tank stores molten glass produced by melting glass raw materials. The walls of the melting tank are in contact with the molten glass and are gradually eroded over time. Therefore, the wall thickness gradually decreases. When the wall thickness becomes smaller than a threshold value, repairs are carried out to extend the tank's life, or the melting tank is shut down as its lifespan has expired.

[0003] Patent Document 1 describes measuring the remaining thickness of the side wall of a melting tank by inserting a metal scale into the joints between the bricks that make up the side wall of the melting tank (see paragraph

[0006] of Patent Document 1).

[0004] Patent Documents 2, 3, and 4 disclose techniques for electrically heating molten glass. The molten glass is electrically heated by a plurality of electrode rods inside a melting tank. A voltage is applied to the molten glass to pass an electric current through the molten glass, thereby generating Joule heat. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-13512 [Patent Document 2] Japanese Patent Application Publication No. 2018-193268 [Patent Document 3] Special Publication No. 61-21170 [Patent Document 4] Japanese Patent Application Publication No. 4-342425 Summary of the Invention [Problem to be solved by the invention]

[0006] When using a metal scale to measure the remaining thickness of the wall of a melting tank for electrical heating, electrical heating of the molten glass is temporarily stopped to prevent an operator from getting an electric shock when measuring the remaining thickness.

[0007] When the electrical heating of the molten glass is temporarily stopped, the temperature of the molten glass fluctuates, which may affect the quality of the glass product. In particular, as the wall erosion progresses and the remaining thickness decreases, the frequency of measuring the remaining thickness increases, which increases the risk of temporarily stopping the electrical heating.

[0008] One aspect of the present disclosure provides a technique for measuring the remaining wall thickness of a melting tank without stopping the electrical heating of the molten glass. [Means for solving the problem]

[0009] A thickness measuring device according to one aspect of the present disclosure measures the thickness of a wall of a melting tank for storing molten glass that is electrically heated. The thickness measuring device includes a metal scale inserted into a through hole in the wall, and an insulating cover that covers at least a portion of the outer peripheral surface of the scale on the outside of the wall. [Effects of the Invention]

[0010] According to one aspect of the present disclosure, at least a portion of the outer surface of the scale is covered with an insulating cover, thereby reducing electric shock to the operator and enabling the remaining thickness of the wall of the melting tank to be measured without stopping the electrical heating of the molten glass. [Brief explanation of the drawings]

[0011] [Figure 1] Figure 1 is a cross-sectional view showing a residual thickness measuring device according to one embodiment, where (A) is a cross-sectional view showing the scale inserted into the through-hole in the side wall, (B) is a cross-sectional view showing the cover abutting the side wall, and (C) is a cross-sectional view showing the scale removed from the through-hole in the side wall. [Figure 2]Figure 2 is a cross-sectional view showing a modified residual thickness measuring device and dissolution tank, where (A) is a cross-sectional view showing the state before the scale is inserted into the through-hole in the side wall, (B) is a cross-sectional view showing the state after the scale has been inserted into the through-hole in the side wall, and (C) is a cross-sectional view showing the state after the scale has been removed from the through-hole in the side wall. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and their description may be omitted. In the specification, the symbol "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0013] Referring to FIG. 1, a residual thickness measuring device 100 according to one embodiment will be described. The residual thickness measuring device 100 measures the residual thickness of the wall of a melting tank 10. The melting tank 10 stores molten glass G obtained by melting glass raw materials. The wall of the melting tank 10 is in contact with the molten glass G and is gradually eroded over time. Therefore, the thickness of the wall of the melting tank 10 gradually decreases. When the wall thickness of the melting tank 10 falls below a threshold, repairs are carried out to extend the tank's life, or the operation of the melting tank 10 is stopped as the tank's life has expired.

[0014] The melting tank 10 has a sidewall 11 that surrounds the molten glass G from the sides, and a bottom wall 12 that supports the molten glass G from below. The sidewall 11 and bottom wall 12 are collectively referred to as the "wall." The wall of the melting tank 10 is made up of a plurality of bricks. The plurality of bricks are arranged with gaps between them to prevent contact with each other due to thermal expansion. The gaps are large enough to prevent leakage of the molten glass G, for example, 0.1 mm to 5 mm. The gaps between adjacent bricks can be used as through-holes 13 for measuring the remaining thickness. Because there are multiple gaps between adjacent bricks, the remaining thickness can be measured at multiple locations.

[0015] The remaining thickness measuring device 100 is used to measure the remaining thickness of, for example, the side wall 11. The remaining thickness measuring device 100 may also be used to measure the remaining thickness of the bottom wall 12. The remaining thickness measuring device 100 is equipped with a scale 110. As shown in FIG. 1(A), the scale 110 is inserted into the through-hole 13 of the side wall 11 and brought into contact with the molten glass G. Since the molten glass G loses heat to the wall of the melting tank 10, it hardens to a certain extent near the wall, preventing the scale 110 from penetrating.

[0016] The scale 110 is, for example, plate-shaped. The thickness of the plate-shaped scale 110 is large enough to allow the scale 110 to be inserted into the gap between adjacent bricks, and is, for example, 0.1 mm to 3 mm. The scale 110 may also be rod-shaped. The diameter of the rod-shaped scale 110 is, for example, 0.1 mm to 3 mm.

[0017] Scale 110 has a leading end surface 111 that contacts molten glass G, a base end surface 112 facing opposite to leading end surface 111, and an outer circumferential surface 113. Scale 110 also has graduations 114 that indicate the distance from leading end surface 111. Scale 114 may also indicate the distance from base end surface 112. In either case, as will be described in detail later, the remaining thickness of side wall 11 can be measured using graduations 114 as shown in FIGS. 1(A) to 1(C).

[0018] The scale 110 rubs against the bricks that make up the side wall 11 when it is inserted into or pulled out of the through-hole 13 in the side wall 11. If the scale 110 is made of metal, the scale 110 is less likely to break and the work is easier. Therefore, in this embodiment, a metal scale 110 is used.

[0019] The molten glass G is electrically heated by a plurality of electrodes (not shown) inside the melting tank 10. Joule heat is generated by applying a voltage to the molten glass G to pass an electric current through the molten glass G. The electrodes are, for example, rod-shaped. The rod-shaped electrodes are inserted into the molten glass G from the bottom wall 12 of the melting tank 10. Alternatively, the rod-shaped electrodes may be inserted into the molten glass G from above or from the side.

[0020] When the plurality of electrodes apply electricity to and heat the molten glass G while the tip surface 111 of the scale 110 is in contact with the molten glass G, electricity flows to the metal scale 110 via the molten glass G. Note that the plurality of electrodes and a gas burner may be used in combination as a heater for heating the molten glass G. In this case as well, electricity flows to the metal scale 110 via the molten glass G.

[0021] Therefore, the remaining thickness measuring device 100 is provided with an insulating cover 120 that covers at least a portion of the outer peripheral surface 113 of the scale 110 on the outside of the side wall 11. The operator holds the scale 110 via the cover 120. This prevents the operator from getting an electric shock and allows the remaining thickness of the side wall 11 to be measured without stopping the electrical heating of the molten glass G. This prevents temperature fluctuations in the molten glass G during the remaining thickness measurement, thereby preventing fluctuations in the quality of the glass product. The insulation resistance of the cover 120 is preferably 0.4 MΩ or more, more preferably 100 MΩ or more, and even more preferably 1 GΩ or more. The higher the insulation resistance of the cover 120, the better, and although there are no particular limitations, from the viewpoint of feasibility, it is preferably 100 TΩ or less.

[0022] The cover 120 only needs to be provided on the outside of the side wall 11, and unlike the scale 110, it does not need to be inserted into the through hole 13 of the side wall 11. This is because an operator performs work outside the side wall 11. Also, by not inserting the cover 120 into the through hole 13 of the side wall 11, it is possible to prevent the cover 120 from breaking inside the through hole 13 and to prevent pieces of the cover 120 from being left behind in the through hole 13.

[0023] The cover 120 has a covering portion 121 that covers at least a portion of the outer peripheral surface 113 of the scale 110. In a cross section perpendicular to the longitudinal direction of the scale 110 (the left-right direction in FIG. 1), it is preferable that the entire outer peripheral surface 113 of the scale 110 is covered with the covering portion 121. In this embodiment, the cover 120 is slidable in the longitudinal direction of the scale 110, but it may not be slidable.

[0024] When the scale 110 is plate-shaped, the covering portion 121 includes, for example, a pair of insulating plates 121a and 121b. The pair of insulating plates 121a and 121b are arranged with the plate-shaped scale 110 sandwiched between them. The pair of insulating plates 121a and 121b are obtained, for example, by processing bricks. It is preferable that the width of the pair of insulating plates 121a and 121b be greater than the width of the scale 110. This can limit contact between the scale 110 and an operator.

[0025] The covering portion 121 may include an insulating tape (not shown) in addition to the pair of insulating plates 121a, 121b. The insulating tape is wound around the pair of insulating plates 121a, 121b. This allows the covering portion 121 to cover the entire outer circumferential surface 113 of the scale 110 in a cross section perpendicular to the longitudinal direction of the scale 110.

[0026] When the scale 110 is rod-shaped, the covering portion 121 includes, for example, a hollow insulating cylinder. The hollow insulating cylinder is obtained, for example, by processing a brick. The scale 110 is inserted into the hollow insulating cylinder. This allows the covering portion 121 to cover the entire outer circumferential surface 113 of the scale 110 in a cross section perpendicular to the longitudinal direction of the scale 110.

[0027] The remaining thickness measuring device 100 includes a limiting member 130 between the scale 110 and the cover 120, which limits the transfer of heat from the scale 110 to the cover 120. The limiting member 130 has, for example, a lower thermal conductivity than both the scale 110 and the cover 120. This makes it possible to suppress a rise in temperature of the cover 120. Note that if the thermal conductivity of the cover 120 is sufficiently low, the limiting member 130 may be omitted.

[0028] In a cross section perpendicular to the longitudinal direction of the scale 110, it is preferable that the entire outer circumferential surface 113 of the scale 110 is covered with the limiting member 130. The limiting member 130 is integrated with the cover 120 and is slidable in the longitudinal direction of the scale 110 together with the cover 120. Note that the limiting member 130 may not be slidable.

[0029] The limiting member 130 is obtained by, for example, processing bricks. The bricks that make up the limiting member 130 have a lower thermal conductivity than the bricks that make up the cover 120. On the other hand, it is preferable that the bricks that make up the cover 120 have a higher electrical resistivity than the bricks that make up the limiting member 130.

[0030] The limiting member 130 may be a spacer that forms an air layer (not shown) between the scale 110 and the cover 120. The thermal conductivity of the air layer is lower than that of bricks. Therefore, by forming the air layer, the transfer of heat from the scale 110 to the cover 120 can be further restricted.

[0031] Next, an example of a method for measuring the remaining thickness will be described with reference again to Figure 1. For example, as shown in Figure 1(A), an operator inserts scale 110 into through-hole 13 of side wall 11, and with tip surface 111 of scale 110 in contact with molten glass G, reads the position of outer surface 15 of side wall 11 using graduations 114 of scale 110. The remaining thickness T of side wall 11 is equal to distance L1 from tip surface 111 of scale 110 to outer surface 15 of side wall 11.

[0032] 1(B), the operator may slide the cover 120 relative to the scale 110 while keeping the tip end surface 111 of the scale 110 in contact with the molten glass G, and bring the cover 120 into contact with the side wall 11. In this case, the operator measures the remaining thickness T of the side wall 11 by reading the distance L2 from the base end surface 112 of the scale 110 to the end surface 129 of the cover 120 opposite to the side wall 11. The lengths of the scale 110 and the cover 120 are measured in advance and are referred to when measuring the remaining thickness T.

[0033] 1(B), the worker may prevent the cover 120 from sliding relative to the scale 110, and then remove the scale 110 from the through-hole 13 of the side wall 11 as shown in FIG. 1(C). In this case, the worker measures the remaining thickness T of the side wall 11 by reading the distance L1 from the tip surface 111 of the scale 110 to the end surface 128 of the cover 120 that faces the side wall 11.

[0034] 1(C), the worker may measure the remaining thickness T of the side wall 11 by reading the distance L2 from the base end surface 112 of the scale 110 to the end surface 129 of the cover 120 opposite to the side wall 11. The lengths of the scale 110 and the cover 120 are measured in advance and are referred to when measuring the remaining thickness T.

[0035] Next, a modified example of a residual thickness measuring device 100 will be described with reference to Fig. 2. Differences will be mainly described below. The residual thickness measuring device 100 comprises a metal scale 110, an insulating cover 120, and a limiting member 130. The cover 120 has a covering portion 121 that covers at least a portion of the outer peripheral surface 113 of the scale 110, and an opposing portion 122 that faces the base end surface 112 of the scale 110.

[0036] The covering portion 121 and the facing portion 122 are integrated together. This can further reduce the risk of electric shock to the worker. When the covering portion 121 and the facing portion 122 are integrated together, the cover 120 may not be able to slide in the longitudinal direction of the scale 110. The cover 120 may have a lid portion 123 that faces the side wall 11. The lid portion 123, the covering portion 121, and the facing portion 122 may be integrated together.

[0037] The remaining thickness measuring device 100 includes a cursor 140 that abuts against the side wall 11 from the outside and slides relative to the scale 110. The cursor 140 is slidable in the longitudinal direction of the scale 110 and indicates the current position of the cursor 140 relative to the scale 110. When the tip surface 111 of the scale 110 abuts against the molten glass G and the cursor 140 abuts against the outer surface 15 of the side wall 11, the cursor 140 indicates the remaining thickness T of the side wall 11 on the scale 114. Providing the cursor 140 makes it easy to read the remaining thickness T.

[0038] Next, an example of a method for measuring the remaining thickness will be described with reference to Figure 2 again. As shown in Figures 2(A) and 2(B), for example, the worker inserts scale 110 into through-hole 13 of side wall 11 and brings tip surface 111 of scale 110 into contact with molten glass G. Before tip surface 111 of scale 110 comes into contact with molten glass G, cursor 140 comes into contact with outer surface 15 of side wall 11, and cursor 140 slides relative to scale 110.

[0039] 2(B), the operator measures the remaining thickness T of the side wall 11 by reading the distance L1 from the tip surface 111 of the scale 110 to the outer surface 15 of the side wall 11. It is preferable that the cursor 140 is transparent. However, even if the cursor 140 is opaque, it is sufficient that the cursor 140 has a shape that allows the operator to read the scale 114. For example, the cursor 140 may have a window for reading the scale 114.

[0040] The worker may prevent the cover 120 from sliding relative to the scale 110 in the state shown in Fig. 2(B), and then remove the scale 110 from the through-hole 13 of the side wall 11 as shown in Fig. 2(C). In this case, after removing the scale 110 from the through-hole 13 of the side wall 11 as shown in Fig. 2(C), the worker measures the remaining thickness T of the side wall 11 by reading the distance L1 from the tip surface 111 of the scale 110 to the scale 110.

[0041] The remaining thickness measuring device, remaining thickness measuring method, and glass manufacturing method according to the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure. [Explanation of symbols]

[0042] 10 Dissolution tank 11 Side wall 12 Bottom wall 13 Through hole 100 Residual thickness measuring device 110 scale 113 Outer surface 120 Cover

Claims

1. A residual thickness measuring device for measuring the residual thickness of a wall of a melting tank that stores molten glass heated by electrical current, a metal scale inserted into the through-hole in the wall; an insulating cover that covers at least a portion of an outer circumferential surface of the scale on the outside of the wall; A remaining thickness measuring device comprising:

2. The residual thickness measuring device according to claim 1 , wherein the scale is plate-shaped or rod-shaped.

3. 3. The residual thickness measuring device according to claim 1, further comprising a limiting member between the scale and the cover, the limiting member limiting heat transfer from the scale to the cover.

4. The residual thickness measuring device according to claim 1 or 2, further comprising a cursor that abuts against the wall from the outside and slides relatively to the scale.

5. the scale has a tip surface that contacts the molten glass, a base end surface facing opposite to the tip surface, and the outer circumferential surface, the cover has a covering portion that covers at least a portion of the outer circumferential surface of the scale and an opposing portion that faces the base end surface of the scale, The remaining thickness measuring device according to claim 1 or 2, wherein the covering portion and the facing portion are integrated.

6. A remaining thickness measuring method, comprising measuring the remaining thickness using the remaining thickness measuring device according to claim 1 or 2.

7. A glass manufacturing method, comprising measuring the remaining thickness using the remaining thickness measuring device according to claim 1 or 2, and electrically heating the molten glass.

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