TW201722864A - Apparatus for heating molten glass, apparatus for producing glass and method for producing glass articles - Google Patents

Abstract

The present invention relates to an apparatus for heating molten glass, an apparatus for producing glass and a method for producing glass articles. The present invention provides a molten glass heating apparatus for heating a molten glass without causing a temperature difference and suppressing the inhomogeneity of the molten glass. A ferroalloy heating device 210 has a composite pipe structure 220 having a main tube 1, an upper branch pipe 2 and a lower branch pipe 3; and a power supply heating portion 230 having an electrode 4, an electrode 5, and an electrode 6, wherein the first current supply path 21 and the second current supply path 22 are formed. The composite pipe structure 220 is formed in a way of satisfying "0.4 < ( the sum of resistance of current flowing between (gamma) the upper end 1a of the main pipe 1 and the upper end Ja of the branch portion and resistance of the current flowing between (beta) the branch portion J and the side end portion 2a of the upper branch pipe 2 / resistance of current flowing between (alpha) the upper end 1a and the lower end 1b of the main pipe 1) < 0.8".

Description

Molten glass heating device, glass manufacturing device, and method for manufacturing glass article

The present invention relates to a molten glass heating apparatus, a glass manufacturing apparatus, and a method of manufacturing a glass article.

In the glass manufacturing apparatus, the high-temperature molten glass is passed through a conduit of the inside thereof using platinum or a hollow tube made of a platinum alloy such as a platinum-gold alloy or a platinum-rhodium alloy. In the glass manufacturing apparatus, in order to ensure the fluidity of the molten glass, the duct through which the molten glass passes is heated. Regarding the heating of the duct, there is a case where the duct is heated by heat from a heater or the like. However, when the duct is a hollow tube made of platinum or a platinum alloy, the following operations are widely performed: in the hollow tube An electrode for energization is provided, and the hollow tube is electrically heated.

When the main pipe and the branch pipe are provided at the time of heating the duct, there is a possibility that the heating in the branch pipe is insufficient.

As a measure against the insufficient heating in the branch pipe, Patent Document 1 discloses a method of electrically heating a composite pipe structure made of platinum which can be used as a conduit for molten glass. As shown in FIG. 7, the composite pipe structure 100 heated by the heating method includes two main pipes 101 and 102, and a branch pipe 103 connecting the main pipes 101 and 102.

In this example, the path for energizing the branch pipe 103 is divided into a first energization path (current supply path) 120 and a second electric path 121. The first power supply path 120 connects the first main pipe 101 and the branch pipe 103. The second electric path 121 connects the branch pipe 103 to the second main pipe 102. Further, each of the first energization path 120 and the second energization path 121 is independently implemented. Electrical control.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2006/123479

However, the heating method of Patent Document 1 does not consider the temperature difference in the inside of the main pipe and in the connection portion (branch portion) between the main pipe and the branch pipe. Therefore, there is a case where the molten glass generates a temperature difference when the molten glass passes through the inside of the main pipe and the branch pipe, resulting in non-homogeneization of the molten glass.

The present invention has been made in view of the above problems, and it is an object of the invention to provide a molten glass heating apparatus capable of suppressing the non-homogeneization of molten glass by heating the molten glass so as not to cause a temperature difference.

In order to solve the above problems, according to an aspect of the present invention, a molten glass heating apparatus including a composite pipe structure through which molten glass passes and an electric heating unit that electrically heats the composite pipe structure are provided, and The composite pipe structure includes: a main pipe that extends substantially perpendicularly with respect to a horizontal direction; an upper branch pipe that branches from the main pipe on a side of the upper portion of the main pipe; and a lower branch pipe that is lateral to the lower side of the main pipe from the above a main branch; the electric heating unit includes a first electrode provided at an upper end of the main tube, a second electrode provided at a lower end of the main tube, and a third electrode provided at a side end of the upper branch tube to form a current Supplying the first current supply path between the first electrode and the second electrode, and forming a second current supply path for supplying a current between the first electrode and the third electrode to the composite tube structure in, And satisfying 0.4<(the total resistance of the current flowing between the upper end of the main tube and the upper end of the branch portion, and the electric resistance of the current flowing between the branch portion of the upper branch pipe and the side end portion) The upper branch pipe is disposed on the main pipe in such a manner that the resistance of the current flowing between the upper end and the lower end of the main pipe is <0.8.

According to an aspect of the present invention, in the molten glass heating apparatus, the molten glass can be heated so as not to cause a temperature difference, thereby suppressing the heterogeneity of the molten glass.

1‧‧‧Supervisor (main body)

1a‧‧‧Upper

1b‧‧‧Bottom

1R‧‧‧Supervisor (main body)

2‧‧‧Upper branch tube

2a‧‧‧ lateral end

2c‧‧‧ side end

2R‧‧‧Upper branch tube

3‧‧‧ Lower branch tube

3a‧‧‧Side side

3R‧‧‧lower branch tube

4 (4a, 4b) ‧ ‧ first electrode

5 (5a, 5b) ‧ ‧ second electrode

6 (6a, 6b) ‧ ‧ third electrode

7 (7a, 7b) ‧ ‧ fourth electrode

10‧‧‧melting device

11‧‧‧ melting furnace

11a‧‧‧ melting room

12‧‧‧ burner

20‧‧‧Melt glass conveying device

21‧‧‧1st current supply path

22‧‧‧2nd current supply path

23‧‧‧3rd current supply path

24A‧‧‧1st power supply

24B‧‧‧2nd power supply

24C‧‧‧3rd power supply

25‧‧‧ Current balancing mechanism

25R‧‧‧current balancing mechanism

30‧‧‧Forming device

31‧‧‧Forming furnace

31a‧‧‧Forming room

32‧‧‧Forming heater

40‧‧‧Connecting device

41‧‧‧Connecting furnace

41a‧‧‧ Connection room

42‧‧‧Intermediate heater

43‧‧‧ lifting roller

50‧‧‧ Slow cooling device

51‧‧‧ Slow cooling furnace

51a‧‧‧ Slow cooling room

52‧‧‧ Slow cooling heater

53‧‧‧ Slow cooling roller

100‧‧‧Composite tube structure

101‧‧‧1st Supervisor

102‧‧‧2nd Supervisor

103‧‧‧ branch tube

120‧‧‧1st electrification path

121‧‧‧2nd electrification path

200‧‧‧Solid glass heating system

210‧‧‧Fusing glass heating device (first molten glass heating device)

220‧‧‧Composite tube structure

230‧‧‧Electric heating unit

240‧‧‧2nd molten glass heating device

250‧‧‧Composite tube structure

260‧‧‧Electric heating unit

311‧‧‧Floating kiln

312‧‧‧ top

D1‧‧‧Inner diameter of main 1

D2‧‧‧The inner diameter of the upper branch tube 2

G1‧‧‧ glass materials

G2‧‧‧ molten glass

G3‧‧‧glass ribbon

Height of Hm‧‧‧Supervisor 1 (length)

H‧‧‧ Distance from the upper end 1a of the main pipe 1 to the upper end Ja of the branch of the upper branch pipe 2

Ia‧‧‧ single phase alternating current

Ib‧‧‧ single phase alternating current

Ic‧‧‧ single phase alternating current

J‧‧‧ branch (connection)

Upper end of the Ja‧‧ branch

Lower end of the Jb‧‧ branch

L‧‧‧The length of the upper branch tube 2

LD‧‧‧ The shortest path from the upper end of the main pipe through the main pipe to the lower end of the branch, and the lower end of the inner peripheral part of the upper branch pipe from the lower end of the upper branch pipe to the upper branch pipe of the upper part of the cylindrical upper branch pipe Total of paths of current flowing at the side ends

M‧‧‧ molten metal

S10‧‧‧ melting step

S20‧‧‧ molten glass transfer step

S30‧‧‧forming steps

S50‧‧‧ Slow cooling step

SD‧‧‧The shortest path from the upper end of the main pipe through the main pipe to the upper end of the branch, and the upper branch from the upper end of the inner branch of the upper branch pipe to the upper branch of the inner branch of the upper branch pipe Total of paths of current flowing at the side ends

α‧‧‧Supervisor 1 overall

β‧‧‧Upper branch tube 2

γ‧‧‧Superior branch of branch 1

Fig. 1 is a cross-sectional view showing a glass manufacturing apparatus equipped with a molten glass heating apparatus according to a first embodiment of the present invention.

Fig. 2 is a flow chart showing a method of manufacturing a glass article of the manufacturing apparatus of Fig. 1.

Fig. 3 is a schematic view showing a molten glass heating apparatus according to a first embodiment of the present invention.

Fig. 4 is a perspective perspective view for explaining a position of an upper branch pipe with respect to a main pipe in the composite pipe structure according to the first embodiment of the present invention.

Fig. 5 is a schematic view showing a system including a molten glass heating apparatus according to a second embodiment of the present invention.

Fig. 6 is a table showing the temperature of the molten glass in the composite pipe structure in which the position of the upper branch pipe is changed with respect to the main pipe.

Fig. 7 is a conceptual diagram of a prior art electric heating device.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same or corresponding numerals, and the description is omitted. In the present specification, the "~" indicating the numerical range means the range including the numerical values before and after.

[Glass manufacturing equipment]

Fig. 1 is a cross-sectional view showing a manufacturing apparatus of a glass plate (glass article) on which a molten glass heating device according to a first embodiment of the present invention is mounted. As shown in FIG. 1, the glass plate manufacturing apparatus has the melting apparatus 10, the molten glass conveying apparatus 20, the molding apparatus 30, the connection apparatus 40, and the slow cooling apparatus 50.

The melting device 10 produces molten glass G2 by melting the glass raw material G1. The melting device 10 has, for example, a melting furnace 11 and a burner 12.

The melting furnace 11 forms a melting chamber 11a that melts the glass raw material G1. The molten glass G2 is accommodated in the melting chamber 11a.

The burner 12 forms a flame in the upper space of the melting chamber 11a. The glass raw material G1 is gradually melted into the molten glass G2 by the radiant heat of the flame.

The molten glass conveying device 20 transfers the molten glass G2 from the melting device 10 to the forming device 30, and supplies the molten glass G2 to the forming device 30. The molten glass heating device 210 is provided in the molten glass conveying device 20.

The molding device 30 forms the molten glass G2 supplied from the molten glass conveying device 20 into a strip-shaped glass ribbon G3. The molding apparatus 30 has, for example, a forming furnace 31 and a shaping heater 32.

The forming furnace 31 forms a forming chamber 31a in which the molten glass G2 is formed. The temperature of the forming chamber 31a is lower as the inlet of the forming furnace 31 faces the outlet of the forming furnace 31. The forming furnace 31 has a floating kiln 311 and a top portion 312 disposed above the floating kiln 311.

The float bath 311 accommodates the molten metal M. As the molten metal M, for example, molten tin is used. In addition to molten tin, a molten tin alloy or the like can also be used. In order to suppress oxidation of the molten metal M, the upper space of the forming chamber 31a is filled with a reducing gas. The reducing gas contains, for example, a mixed gas of hydrogen and nitrogen.

The float bath 311 is formed into a strip-shaped glass ribbon G3 by using the liquid surface of the molten metal M to continuously supply the molten glass G2 supplied onto the molten metal M. The glass ribbon G3 is gradually solidified while flowing from the upstream side to the downstream side of the floating kiln 311, and is downstream of the floating kiln 311. The molten metal M is lifted in the area.

Forming heater 32 is suspended from top 312. The forming heaters 32 are provided at a plurality of intervals in the flow direction of the glass ribbon G3, and the temperature distribution in the flow direction of the glass ribbon G3 is adjusted. Further, a plurality of the forming heaters 32 are provided at intervals in the width direction of the glass ribbon G3, and the temperature distribution in the width direction of the glass ribbon G3 is adjusted.

The connecting device 40 connects the forming device 30 and the slow cooling device 50. The insulating material can be filled in a narrow gap between the connecting device 40 and the slow cooling device 50. The connecting device 40 has a connection furnace 41, an intermediate heater 42, and a lift roller 43.

The connection furnace 41 is disposed between the forming furnace 31 and the slow cooling furnace 51 described below, and forms a connection chamber 41a that restricts the heat removal of the glass ribbon G3 conveyed between them. The quenching of the glass ribbon G3 can be prevented between the forming furnace 31 and the slow cooling furnace 51.

The intermediate heater 42 is disposed in the connection chamber 41a. The intermediate heaters 42 are provided at a plurality of intervals in the conveying direction of the glass ribbon G3, and the temperature distribution in the conveying direction of the glass ribbon G3 is adjusted. The intermediate heater 42 can also be divided in the width direction of the glass ribbon G3 to adjust the temperature distribution in the width direction of the glass ribbon G3.

The lift roller 43 is disposed in the connection chamber 41a. The lift roller 43 is rotationally driven by a motor or the like, lifts the glass ribbon G3 from the molten metal M, and conveys it from the forming furnace 31 to the slow cooling furnace 51. A plurality of lifting rollers 43 are provided at intervals in the conveying direction of the glass ribbon G3.

The slow cooling device 50 will slowly cool the glass ribbon G3 formed in the forming device 30. The slow cooling device 50 has a slow cooling furnace 51, a slow cooling heater 52, and a slow cooling roller 53.

The slow cooling furnace 51 forms a slow cooling chamber 51a for slowly cooling the glass ribbon G3. The temperature of the slow cooling chamber 51a is lower as the inlet of the slow cooling furnace 51 is directed toward the outlet of the slow cooling furnace 51.

The slow cooling heater 52 is disposed in the slow cooling chamber 51a. The slow cooling heaters 52 are provided at a plurality of intervals in the conveying direction of the glass ribbon G3, and the temperature distribution in the conveying direction of the glass ribbon G3 is adjusted. The slow cooling heater 52 can also be divided in the width direction of the glass ribbon G3. The cutting is performed to adjust the temperature distribution in the width direction of the glass ribbon G3.

The slow cooling roller 53 is disposed in the slow cooling chamber 51a. The slow cooling roller 53 is rotationally driven by a motor or the like to convey the glass ribbon G3 from the inlet of the slow cooling furnace 51 toward the outlet of the slow cooling furnace 51. The slow cooling rolls 53 are provided at a plurality of intervals in the conveying direction of the glass ribbon G3.

The slow-cooled glass ribbon G3 in the slow cooling device 50 is cut into a specific size by a cutter to obtain a glass plate as a product.

Furthermore, the manufacturing apparatus of the glass plate can be various. For example, the glass plate manufacturing apparatus may have a clarification device for defoaming the bubbles contained in the molten glass G2 in the molten glass conveying device 20.

[Method of manufacturing glass articles]

Next, a method of manufacturing a glass sheet using the apparatus for manufacturing a glass sheet having the above configuration will be described with reference to Fig. 2 . Fig. 2 is a flow chart showing a method of manufacturing the glass article of the first embodiment. As shown in FIG. 2, the manufacturing method of a glass plate has the melting process S10, the molten glass conveyance process S20, the shaping|molding process S30, and the slow-cooling process S50.

In the melting step S10, the molten glass G2 is produced by melting the glass raw material G1.

In the molten glass transfer step S20, the molten glass G2 is transferred from the melting device 10 to the molding device 30.

In the molding step S30, the molten glass G2 produced by the melting step S10 is formed into a strip-shaped glass ribbon G3. For example, in the molding step S30, the molten glass G2 is continuously supplied onto the molten metal M, and the molten glass G2 is formed into a strip-shaped glass ribbon G3 by the liquid surface of the molten metal M. The glass ribbon G3 flows from the upstream side to the downstream side of the floating kiln 311, and is gradually solidified.

In the slow cooling step S50, the glass ribbon G3 formed by the forming step S30 is slowly cooled.

The slow-cooled glass ribbon G3 is cut into a specific size by a cutter to obtain a glass plate as a product.

Furthermore, the method of manufacturing the glass sheet can be various. For example, the method of producing a glass sheet may have a clarification step of defoaming the bubbles contained in the molten glass G2 in the molten glass conveying step S20.

[Molten Glass Heating Device]

<First embodiment>

Next, the molten glass heating apparatus 210 of the present invention will be described with reference to Fig. 3 . Fig. 3 is a schematic view for explaining the molten glass heating apparatus 210 according to the first embodiment of the present invention.

The molten glass heating device 210 includes a composite pipe structure 220 and an electric heating unit 230. The composite pipe structure 220 includes a conduit that forms a flow path through which the molten glass G2 passes. The electric heating unit 230 energizes the composite pipe structure 220.

The composite pipe structure 220 shown in Fig. 3 includes a main pipe (also referred to as a main pipe) 1, an upper branch pipe 2, and a lower branch pipe 3 as pipes.

The main pipe 1 extends substantially perpendicularly to the horizontal direction, and the upper branch pipe 2 branches from the main pipe 1 on the upper side of the main pipe 1, and the inside thereof communicates with the main pipe 1. Here, the term "substantially perpendicular to the horizontal direction" means within ±10 degrees with respect to the vertical direction. The lower branch pipe 3 branches from the main pipe 1 to the lower side of the main pipe 1, and is internally connected to the main pipe 1.

In the configuration of Fig. 3, the lower branch pipe 3 is an introduction pipe for introducing the molten glass G2 into the main pipe 1, and the upper branch pipe 2 is a discharge pipe for discharging the molten glass G2 from the main pipe 1, but it may be as shown in Fig. 5 below. The opposite constitutes.

The main pipe 1, the upper branch pipe 2, and the lower branch pipe 3 are hollow pipes made of platinum or platinum alloy. Specific examples of the platinum alloy include a platinum-gold alloy and a platinum-rhodium alloy. Further, in the case of platinum or a platinum alloy, the reinforced platinum which is obtained by dispersing a metal oxide in platinum or a platinum alloy is also included. In this case, as the metal oxide to be dispersed, a metal oxide of Group III, Group IV or Group 13 of the periodic table typified by Al ₂ O ₃ or ZrO ₂ or Y ₂ O ₃ may be mentioned.

In order to introduce a current into the wall of the platinum-containing hollow tube, the upper end 1a of the main pipe 1, the lower end 1b of the main pipe 1, the side end 2a of the upper branch pipe 2, and the side end of the lower branch pipe 3 are provided. 3a is provided with the following electrodes 4, 5, 6, and 7.

A cover member for preventing heat dissipation from the molten glass G2 may be provided on the outer side (upper side) of the electrode 4 provided on the upper end 1a of the main pipe 1.

In the energization heating unit 230 that energizes and heats the composite pipe structure 220 having the above configuration, the electrode 4 is joined to the outer periphery of the upper end 1a of the main pipe 1, the electrode 5 is joined to the outer periphery of the lower end 1b of the main pipe 1, and the electrode 6 is joined to the upper portion. The outer circumference of the side end portion 2a of the branch pipe 2 and the electrode 7 are joined to the outer circumference of the side end portion 3a of the lower branch pipe 3.

The electrodes 4, 5, 6, and 7 include annular electrodes 4a, 5a, 6a, and 7a made of platinum or platinum alloy, and lead electrodes joined to one end of the outer edges of the annular electrodes 4a, 5a, 6a, and 7a. 4b, 5b, 6b, 7b. The extraction electrodes 4b, 5b, 6b, and 7b are connected to the power sources 24A, 24B, and 24C described below, and when energization is performed, current is drawn from the extraction electrodes 4b, 5b, 6b, and 7b to the catheter via the annular electrodes 4a, 5a, 6a, and 7a. 1, 2, 3 flow.

A portion made of a metal material other than platinum or a platinum alloy may be provided on the outer edge of the annular electrodes 4a, 5a, 6a, and 7a. Examples of such a metal material include ruthenium, rhodium, molybdenum, tungsten, nickel, palladium, copper, and the like.

As for the extraction electrodes 4b, 5b, 6b, and 7b, platinum is also preferably used as a main constituent material. However, the present invention is not limited thereto, and may be made of a metal material other than the above platinum or platinum alloy.

Further, a first current supply path 21 for connecting an electrode (first electrode) 4 of the upper end 1a of the main pipe 1 to an electrode (second electrode) 5 of the lower end 1b and supplying a current is formed. A second current supply path 22 that connects the electrode 4 of the upper end 1a of the main pipe 1 to the electrode 6 (third electrode) of the side end 2a of the upper branch pipe 2 and supplies a current is formed. A third current supply path 23 that connects the electrode 5 of the lower end 1b of the main pipe 1 to the electrode (fourth electrode) 7 of the side end portion 3a of the lower branch pipe 3 and supplies a current is formed.

The first current supply path 21 supplies current to the electrodes 5 and 4, the second current supply path 22 supplies current to the electrodes 4 and 6, and the third current supply path 23 supplies current to the electrodes 7 and 5, thereby applying to the composite tube structure. 220 is energized and heated.

Further, in the energization heating unit 230, the first power supply path 21 is provided with the first power supply 24A, the second current supply path 22 is provided with the second power supply 24B, and the third current supply path 23 is provided with the second current supply path 23. The third power source 24C. That is, the first power source 24A is electrically connected to the electrodes 5 and 4, the second power source 24B is electrically connected to the electrodes 4 and 6, and the third power source 24C is electrically connected to the electrodes 7 and 5.

Further, the energization heating unit 230 includes a current balancing mechanism 25 that performs current (current density) between the electrodes of the first current supply path 21, the second current supply path 22, and the third current supply path 23. Adjustment.

As an example, the three-phase AC power source 24A, the power source 24B, and the power source 24C supply a single-phase AC current ia, a single-phase AC current ib, and a single-phase AC current ic, respectively.

Here, the current balancing mechanism 25 has a current balancing function, that is, a current level of a single-phase alternating current ia, a single-phase alternating current ib, and a single-phase alternating current ic generated by the power source 24A, the power source 24B, and the power source 24C. Make adjustments to achieve a balance of current levels between the power supplies. As the adjustment of the current level, the phase of the current can also be adjusted.

The current balancing mechanism 25 includes, for example, a transformer including a plurality of coils for adjusting the turns ratio of the single-phase alternating current between R, S, R, T, S, and T among the three-phase alternating current phases, and three-terminal bidirectional Control switch, Automatic Current Regulator (ACR, automatic current regulator), etc.

3, the example in which the current balancing mechanism 25 and the power sources 24A, 24B, and 24C are separately described has been described. However, the current balancing mechanism 25 and the power sources 24A, 24B, and 24C may be combined to form a power supply system. .

As an example, the current balancing mechanism 25 of the present embodiment has a single-phase alternating current ia of the power source 24A, a single-phase alternating current ib of the power source 24B, and a single-phase alternating current ic of the power source 24C. The current is adjusted such that the phase difference is 2π/3 and 4π/3. When the phase difference is set in this way, the sum of the potential differences of the three power sources 24A, 24B, and 24C is always fixed.

Thereby, the current ia flowing through the first current supply path 21 connected to the upper end 1a and the lower end 1b of the main pipe 1 and the second current connected to the upper end 1a of the main pipe 1 and the side end 2a of the upper branch pipe 2 are supplied. The current ib flowing through the path 22 and the current ic flowing through the third current supply path 23 connecting the lower end 1b of the main pipe 1 and the side end portion 3a of the lower branch pipe 3 are controlled to be equal to each other.

In the case where a uniform current is supplied to each of the current supply paths as described above, in FIG. 3, the upper end of the branch portion of the main pipe 1 and the upper branch pipe 2 (the upper end and the upper corner of the connecting portion) Ja, from the first The current supplied from the current supply path 21 and the second current supply path 22 repeatedly flows. Further, the upper end Ja of the branch portion is located at the shortest path of the current flowing from the upper end 1a of the main pipe 1 to the upper branch pipe 2. Therefore, the upper end Ja of the branch portion becomes a portion where current concentrates.

As a result, the upper end Ja of the branch portion is concentrated due to the current, so that local heating is generated.

Therefore, it is preferable that local heating is not performed at the upper end Ja of the branch portion when the upper branch pipe 2 is electrically heated. Therefore, in the present embodiment, the concentration of the composite pipe structure 220 is specified to alleviate the concentration of the current. . Specifically, in the molten glass heating apparatus 210 of the present embodiment, the position of the upper branch pipe 2 is appropriately set in the height (length) Hm of the main pipe 1 in the composite pipe structure 220, so that it can be used in the branch portion. The power supply control is easily and appropriately performed in such a manner that local heating is not generated at the upper end Ja.

Here, regarding the cause of the specific local heating, the size of the composite pipe structure 220 was examined.

When the composite pipe structure 220 surrounding the molten glass G2 is electrically heated, P is set to heat (W), I is set to current (A), and R is set to a resistance value (Ω), and the following formula: 1]P=I ² × R ‧‧‧(1)

Produce heat. Here, if H is set to calorific value (J) and T is set to time (sec), then Produce [number 2] H = P. T‧‧‧(2)

The heat is generated.

At this time, the current flowing is V to be set to electric (V), as shown below.

Here, the electric resistance system sets S as the cross-sectional area (m ² ) of the conductor (conduit), 1 is the length (m) of the conductor, and ρ is the specific resistance (resistivity) (Ω‧ m) of the material. And the following formula indicates that

If the inner diameter (inner diameter) of the catheter is set to D, and the thickness of the catheter is set to t, and applied to the formula (4),

Here, since the thickness t of the main pipe 1 and the upper branch pipe 2 is about 0.1 mm to 3 mm, the inner diameter D of the pipe is remarkably small (D>>t), and the formula (5) can be approximated as follows.

Since π is the pi, ρ is the specific resistance of the material, and t is the thickness, so "2ρ/πt" of the formula (6) is fixed in all the conduits 1, 2, and 3. Therefore, in the composite pipe structure 220 of the present embodiment, the ratio of "l/D" of the portion where the current flows is compared, whereby the resistance value R of the conduit and the current value of the flow can be compared. The amount of current is used to predict the generation of local heat.

In the present embodiment, in order to prevent local heat generation at the upper end Ja of the branch portion, the size and connection position (branch position) of each of the conduits in the composite pipe structure 220 are set as follows. Further, these dimensions are defined in consideration of the temperature calculation results of the following examples.

Further, the size of the annular electrodes 4, 5, 6, 7 provided at the upper end 1a, the lower end 1b of the main pipe, the side ends 2a, 3a of the branch pipes 2, 3, and the cylinders of the pipes 1, 2, 3 The size of the body portion is as small as negligible. Thereby, the electric resistance of the electrodes 4, 5, 6, and 7 is set to be as small as negligible as compared with the electric resistance of the cylindrical main body of the ducts 1, 2, and 3.

4 is a perspective perspective view illustrating the position of the upper branch pipe 2 with respect to the main pipe 1. In Fig. 4, α indicates the entirety of the main pipe 1, β indicates the upper branch pipe 2, and γ indicates the upper portion of the branch in the main pipe 1 (the portion above the upper end Ja of the branch portion).

In the present embodiment, in order to appropriately set the position of the upper branch pipe 2 with respect to the main pipe 1, it is preferable to specify the position (distance h) from the upper end 1a of the main pipe 1 to the upper end Ja of the branch portion as described below.

In the present embodiment, it is preferable that "0.4" (resistance of a current flowing between the upper end 1a of the main pipe 1 and the upper end Ja of the branch portion (γ), and the branch portion J and the side end of the upper branch pipe 2 are satisfied. The sum of the electric resistances of the currents flowing between the portions 2a (β) / the electric resistance of the current flowing between the upper end 1a and the lower end 1b of the main pipe 1 (α) is <0.8".

Here, "the resistance of the current flowing between the upper end 1a of the main pipe 1 and the upper end Ja of the branch portion (γ)] and [the branch portion J of the upper branch pipe 2 and the side end portion 2a (β The total value of the resistance of the flowing current is divided by the value obtained by [the electric resistance of the current flowing between (α) between the upper end 1a and the lower end 1b of the main pipe 1" as the ratio A.

Here, the branch portion J of the upper branch pipe 2 refers to a connection portion between the main pipe 1 and the upper branch pipe 2. For example, when the main pipe 1 extends in the vertical direction and the upper branch pipe 2 branches vertically from the main pipe 1, the branch portion J as the connecting portion has a substantially circular shape.

The ratio A is more preferably greater than 0.45, and still more preferably greater than 0.5. Further, the ratio A is more preferably less than 0.75, still more preferably less than 0.7.

As a specific example, the main pipe 1 extends in the vertical direction, the upper branch pipe 2 branches perpendicularly to the main pipe 1 and extends in the horizontal direction, and the electrode 6 of the side end portion 2a is vertically disposed with respect to the upper branch pipe 2. In the case, the ratio A is expressed by the following formula.

The height (length) of the main pipe 1 is set to Hm, the inner diameter of the main pipe 1 is set to D1, and the length of the upper branch pipe 2 (that is, the length of the bus bar of the circumferential surface of the cylindrical upper branch pipe 2) is set. In the case of L, the inner diameter of the upper branch pipe 2 is set to D2, and when the distance from the upper end 1a of the main pipe 1 to the upper end Ja of the branch portion of the upper branch pipe 2 is h, the upper branch pipe is provided with respect to the main pipe 1. The position of 2 can be set to:

In this case, it is also preferable to satisfy 0.4 < ratio A = ((h / D1) + (L / D2)) / (Hm / D1) < 0.8.

Here, the upper branch pipe 2 may also be inclined without being extended in the horizontal direction. When the upper branch pipe 2 is not inclined in the horizontal direction and is inclined, and the electrode 6 of the side end portion 2a is provided in the vertical direction, it is not necessary to correct it by the formula (7).

Furthermore, the ratio A is not limited to the formula (7). For example, when the upper branch pipe 2 is not inclined in the horizontal direction and the electrode 6 of the side end portion 2a is not disposed in the vertical direction, the cross-sectional area S and the length L of the upper branch pipe 2 (β) are based on According to the relationship between the angle of the branch and the angle of the end, it is necessary to perform the addition or subtraction correction by the equation (7).

Regardless of the case where the upper branch pipe 2 is horizontal or inclined, the above ratio A indicates "[resistance of current flowing in the upper portion of the branch in the main pipe 1] and [in the upper branch pipe] The total of the resistance of the current flowing through 2 (β) is divided by the ratio of [the resistance of the current flowing in the whole α of the main pipe 1].

By setting 0.4<the ratio A<0.8 in this manner, local heating by the upper end Ja of the branch portion can be suppressed, and the molten glass G2 can be uniformly heated in the composite pipe structure 220, whereby the heterogeneity can be suppressed.

Further, in the present invention, the position at which the upper branch pipe 2 is provided with respect to the upper end 1a of the main pipe 1 preferably satisfies the following formula. Here, in FIG. 3, the branch lower end Jb is the lower end (lower corner) of the connection part of the main pipe 1 and the upper branch pipe 2.

"0.55 < (the shortest path from the upper end 1a of the main pipe 1 through the main pipe 1 to the upper end Ja of the branch portion, and the upper end of the self-branch portion Ja through the uppermost portion of the inner peripheral portion of the upper branch pipe 2 along the cylindrical upper branch pipe 2 The total SD of the path of the current flowing in the busbar direction toward the side end portion 2a of the upper branch pipe 2, the shortest path from the upper end 1a of the main pipe 1 through the main pipe 1 to the lower end Jb of the branch portion, and the shortest path from the lower end Jb of the branch portion The total LD) <0.77 of the path of the current flowing in the lowermost portion of the inner peripheral portion of the upper branch pipe 2 toward the side end portion 2a of the upper branch pipe 2 in the direction of the bus bar of the cylindrical upper branch pipe 2

Here, "the shortest path from the upper end 1a of the main pipe 1 through the main pipe 1 to the upper end Ja of the branch portion, and the upper end of the self-branch portion Ja through the uppermost portion of the inner peripheral portion of the upper branch pipe 2 are above the cylindrical shape. The total SD of the path of the current flowing in the busbar direction of the partial branch pipe 2 toward the side end portion 2a of the upper branch pipe 2 is divided by [the shortest path of the current flowing from the upper end 1a of the main pipe 1 through the main pipe 1 to the lower end Jb of the branch portion, And the total LD of the path of the current flowing from the lower end of the inner peripheral portion of the upper branch pipe 2 to the side end portion 2a of the upper branch pipe 2 in the direction of the busbar of the upper portion of the upper branch pipe 2 The ratio is defined as the ratio B.

Since the main pipe 1 is disposed substantially perpendicularly to the horizontal direction, current flows from the upper end 1a of the main pipe 1 through the main pipe 1 to the upper end Ja of the branch portion in a substantially vertical direction.

Moreover, the current flows from the upper end 1a of the main pipe 1 through the main pipe 1 to the main pipe 1 and the upper branch pipe 2 After the side end (left end or right end) of the joint portion (that is, the branch portion J of the upper branch pipe 2) flows in the substantially vertical direction, the side end from the branch portion J flows along the circular arc of the branch portion J toward the lower end portion Jb of the branch portion. .

Further, as shown in Fig. 4, when the main pipe 1 extends in the vertical direction and the upper branch pipe 2 branches vertically from the main pipe 1, the direction of the bus bar of the partial branch pipe 2 in the horizontal cylindrical shape is the horizontal direction.

The ratio B is more preferably greater than 0.60. Also, the ratio B is more preferably less than 0.70.

As a specific example, the main pipe 1 extends in the vertical direction, the upper branch pipe 2 branches vertically from the main pipe 1 and extends in the horizontal direction, and the electrode 6 of the side end portion 2a is vertically disposed with respect to the upper branch pipe 2 When the length of the bus bar of the partial branch pipe 2 above the straight cylindrical shape is equal to the length L of the upper branch pipe 2, the ratio B can be set as follows:

In this case, it is also preferable to satisfy 0.55 < ratio B = (h + L) / (h + (5 / 4) D2 + L) < 0.77.

Furthermore, as shown in FIG. 4, the current passing through the path SD (h+L) passes through the upper end of the branch portion of the main pipe 1 and the upper branch pipe 2, and the current through the path LD (h+(5/4)D2+L) passes. The lower end of the branch is Jb.

Here, the upper branch pipe 2 may also be inclined without being extended in the horizontal direction. The upper branch pipe 2 is inclined without being extended in the horizontal direction, and the electrode 6 of the side end portion 2a is provided in the vertical direction, and is a circular side end portion 2a which becomes the bottom surface of the cylinder of the upper branch pipe 2. The oblique cylindrical shape that obliquely intersects the busbar of the circumferential surface does not need to be corrected by the equation (8).

Furthermore, the ratio B is not limited to the formula (8). For example, when the upper branch pipe 2 does not extend in the horizontal direction and is inclined, and the electrode 6 of the side end portion 2a is not disposed in the vertical direction, Regarding the length L of the upper branch pipe 2 (β), based on the relationship between the angle of the branch and the angle of the end portion, there may be a case where the correction of the addition or subtraction by the equation (8) is required. For example, it is a case where a straight cylindrical shape in which the bottom surface and the busbar of the circumferential surface intersect at right angles is inclined and cut and connected.

In this way, "the shortest path from the upper end 1a of the main pipe 1 through the main pipe 1 to the upper end Ja of the branch portion, and the upper end of the self-branch portion Ja through the uppermost portion of the inner peripheral portion of the upper branch pipe 2 along the cylindrical upper branch pipe" The total SD of the path of the current flowing toward the side end 2a of the upper branch pipe 2 in the direction of the busbar 2 of 2 is divided by the shortest path of the current flowing from the upper end 1a of the main pipe 1 through the main pipe 1 to the lower end Jb of the branch portion, and the self-division The ratio of the lower end Jb of the branch portion to the total LD of the path of the current flowing toward the side end portion 2a of the upper branch pipe 2 in the direction of the busbar of the upper portion of the cylindrical upper branch pipe 2 at the lowermost portion of the inner peripheral portion of the upper branch pipe 2" The ratio B includes both the case where the upper branch pipe 2 is horizontal (in the case of a straight cylindrical shape) and the case where the upper branch pipe 2 is horizontal (in the case of a straight cylindrical shape or a case of an oblique cylindrical shape).

By setting 0.55 < ratio B < 0.77 in this manner, the temperature difference between the upper side and the lower side of the inside of the tube of the upper branch pipe 2 can be suppressed, and the temperature difference of the molten glass G2 in the composite pipe structure 220 can be suppressed. produce.

The relationship between the changes in the ratios A and B when the size of the composite pipe structure 220 and the installation position of the upper branch pipe 2 are changed is as follows.

When the distance h from the upper end 1a of the main pipe 1 to the upper end Ja of the branch portion of the upper branch pipe 2 becomes longer, either the ratio A or the ratio B becomes larger.

If the height Hm of the main pipe 1 becomes low, the ratio B remains unchanged, but the ratio of the portion β above the branch becomes large, so the ratio A becomes large.

When the length L of the upper branch pipe 2 becomes long, either the ratio A or the ratio B becomes large.

When two or more sizes such as the distance h and the height Hm are changed, the ratio A and the ratio B change in accordance with the ratio of the change.

When the length of the conduit is set to satisfy the above ratio, the height Hm of the main pipe 1 is preferably 500 mm to 3000 mm, and the length L of the upper branch pipe 2 is preferably 50 mm to 1500 mm. The height Hm is more preferably 800 mm or more, and still more preferably 1100 mm or more. Further, the height Hm is more preferably 2700 mm or less, and still more preferably 2400 mm or less. The length L is more preferably 150 mm or more, and still more preferably 250 mm or more. Further, the length L is more preferably 1300 mm or less, and still more preferably 1100 mm or less. When the height Hm of the main pipe 1 is 3000 mm or less, the electric resistance of the current of the main pipe 1 can be suppressed, and the molten glass G2 can be sufficiently heated. Moreover, when the length L of the upper branch pipe 2 is 1500 mm or less, the electric resistance of the electric current of the upper branch pipe 2 can be suppressed, and the molten glass G2 can be fully heated.

Further, the inner diameter D1 of the main pipe 1 is preferably 50 mm to 500 mm. The inner diameter D1 is more preferably 100 mm or more, and still more preferably 150 mm or more. Further, the inner diameter D1 is more preferably 450 mm or less, further preferably 400 mm or less.

In order to arrange the upper branch pipe 2 on the upper portion of the main pipe 1 (from more than half), the inner diameter D2 of the upper branch pipe 2 must be shorter than one half of the height Hm of the main pipe, and the inner diameter D2 of the upper branch pipe 2 is preferably 50 mm to 500 mm. . The inner diameter D2 is more preferably 100 mm or more, and still more preferably 150 mm or more. Further, the inner diameter D2 is more preferably 450 mm or less, further preferably 400 mm or less.

In order to set the upper branch pipe 2 to the upper portion of the main pipe 1 (from more than half), the distance h from the upper end 1a of the main pipe 1 to the upper end of the branch portion of the upper branch pipe 2 must be shorter than one half of the height Hm of the main pipe 1, and the distance h is smaller than Good for 50mm~500mm. The distance h is more preferably 100 mm or more, and still more preferably 150 mm or more. Further, the distance h is preferably 450 mm or less, and more preferably 400 mm or less.

If the distance h is too short, the upper branch pipe 2 is close to the upper end 1a of the main pipe 1, so that there is a trap of air bubbles during the transfer of the molten glass G2. If the distance h is too long, the temperature of the upper end Ja of the branch becomes easy. It is raised, so that the occurrence of a bad situation can be suppressed by setting an appropriate distance h.

Further, in the glass manufacturing apparatus, a stirrer for stirring the molten glass G2 may be provided in the main pipe 1 of the composite pipe structure 220. When the main pipe 1 is provided with a stirrer, the homogenization of the state (temperature, homogeneity, etc.) of the molten glass G2 can be improved.

Further, when the above configuration is observed from above, the lower branch pipe 3 is provided on the side opposite to the main pipe 1 on the side opposite to the upper branch pipe 2, but the upper branch pipe 2 and the lower branch pipe 3 need not be provided at 180 degrees. On the opposite side, it can also be set to a specific angle of 45 degrees or more.

Further, although the case where the branch pipes 2, 3 are branched horizontally from the main pipe 1 has been described above, the branch pipes 2, 3 may be branched from the main pipe 1 without being vertically inclined. In this case, it is also preferable to form the composite pipe structure 220 so as to satisfy the ratio as described above.

<Second embodiment>

In the present embodiment, a case where two of the molten glass heating devices are arranged in parallel in the molten glass conveying device 20 shown in Fig. 1 will be described.

Fig. 5 shows a system 200 including a molten glass heating apparatus according to a second embodiment of the present invention.

Similarly to the configuration of Fig. 3, in the composite pipe structure 220 of the molten glass heating apparatus 210 on the left side of Fig. 5, the lower branch pipe 3 is an inlet pipe on the inlet side where the molten glass G2 is introduced into the main pipe 1. Part of the branch pipe 2 is a discharge pipe that discharges the molten glass G2 from the main pipe 1.

In the composite pipe structure 250 of the second molten glass heating apparatus 240, the upper branch pipe 2R introduces the molten glass G2 discharged from the upper branch pipe 2 into the inlet pipe of the inlet side of the main pipe 1R, and the lower branch pipe 3R is already The tube on the outlet side discharged through the molten glass G2 of the main pipe 1R. The side end portion 2c of the upper branch pipe 2R is disposed to face the side end portion 2a of the portion branch pipe 2 above the first molten glass heating device 210.

In the present embodiment, the electric heating is performed on the first molten glass heating device 210. In the unit 230 and the energization heating unit 260 of the second molten glass heating device 240, the current balancing mechanisms 25 and 25R are provided, respectively, so that the energization heating is independently controlled.

The molten glass heating apparatus (system) according to the embodiment of the present invention is not limited to the floating method shown in Figs. 1 and 2, and can be applied to a melting method or a method of producing another glass article.

Further, the glass article produced by using the glass manufacturing apparatus equipped with the molten glass heating device of the present invention is not limited to the glass plate, and may have various shapes.

In the above, the embodiment of the molten glass heating apparatus has been described. However, the present invention is not limited to the above-described embodiments and the like, and various changes and modifications can be made within the scope of the gist of the invention described in the claims.

[Examples]

With respect to the above molten glass heating device, the size was changed, and the surface temperature of the composite pipe structure was calculated by simulation (finite element method). The following Examples 1 to 7 are examples, and Examples 8 to 10 are comparative examples.

<Example 1~10>

In Example 1, the dimensions of the respective portions in the molten glass heating apparatus were as follows.

Supervisor height Hm: 1000mm

Main diameter D1: 200mm

Branch pipe length L: 450mm

Branch pipe inner diameter D2: 200mm

The distance between the upper end of the main pipe and the upper end of the branch pipe is h: 220mm

In Examples 2 to 10, the dimensions of the respective portions of the molten glass heating apparatus of Example 1 were changed as shown in Fig. 6 .

In the table of Fig. 6, T0 represents the temperature of the central portion of the main pipe 1, T1 represents the temperature of the upper portion of the main pipe 1 (the upper portion γ of the branch), and T2 represents the upper end (corner portion) of the branch portion of the main pipe 1 and the upper branch pipe 2 The temperature, and T3, indicate the temperature of the lower end (corner) Jb of the branch portion of the main pipe 1 and the upper branch pipe 2.

Further, the central portion of the main pipe 1 having the calculated temperature T0 means the vertical direction position of about one-half of the height Hm of the main pipe 1.

As can be seen from Fig. 6, when the ratio A is 0.33 (Example 8) and 1.41 (Example 9), the temperature difference between the central portion of the main pipe 1 and the upper portion of the branch γ, the central portion of the main pipe 1 and the upper end of the branch portion <T1-T0 >, <T2-T0> exceeds 20 °C. Further, when the ratio A is 0.80 (Example 10), the temperature difference <T2-T0> and <T3-T0> between the center portion of the main pipe 1 and the upper end of the branch portion Ja, the center portion of the main pipe 1, and the lower end Jb of the branch portion respectively exceed 20 ° C.

Thus, the ratio A is preferably more than 0.4 and less than 0.8.

Further, as is clear from Fig. 6, when the ratio B is 0.44 (Example 8) and 0.77 (Example 9), the temperature difference between the center portion of the main pipe 1 and the branch upper portion γ, the center portion of the main pipe 1 and the upper end portion of the branch portion <T1 -T0> and <T2-T0> respectively exceed 20 °C. Further, when the ratio B is 0.90 (Example 10), the temperature difference between the central portion of the main pipe 1 and the upper end of the branch portion Ja, the central portion of the main pipe 1 and the lower ends of the branch portions Jb<T2-T0> and <T3-T0> respectively exceed 20 ° C.

Thus, the ratio B is preferably more than 0.55 and less than 0.77.

Further, in the case of setting the size, it is more preferable to satisfy the range of the above two in the range of the ratio A and the ratio B.

When the range of both the ratio A and the ratio B is satisfied, as shown in the example 1 to the example 7, the central portion of the main pipe 1 and the upper portion γ of the branch, the central portion of the main pipe 1 and the upper end of the branch portion Ja, It is preferable that the temperature difference between the central portion of the main pipe 1 and the lower end Jb of the branch portion is <T1-T0>, <T2-T0>, and <T3-T0>.

[Industrial availability]

Since the molten glass heating apparatus of the present invention can electrically heat and heat the entire main pipe and the branch pipe included in the composite pipe structure to a desired temperature, it can be applied to the electric heating of the flow path of the molten glass in the glass manufacturing apparatus.

1‧‧‧Supervisor (main body)

1a‧‧‧Upper

1b‧‧‧Bottom

2‧‧‧Upper branch tube

2a‧‧‧ lateral end

3‧‧‧ Lower branch tube

3a‧‧‧Side side

4 (4a, 4b) ‧ ‧ first electrode

5 (5a, 5b) ‧ ‧ second electrode

6 (6a, 6b) ‧ ‧ third electrode

7 (7a, 7b) ‧ ‧ fourth electrode

21‧‧‧1st current supply path

22‧‧‧2nd current supply path

23‧‧‧3rd current supply path

24A‧‧‧1st power supply

24B‧‧‧2nd power supply

24C‧‧‧3rd power supply

25‧‧‧ Current balancing mechanism

210‧‧‧Fusing glass heating device (first molten glass heating device)

220‧‧‧Composite tube structure

230‧‧‧Electric heating unit

D1‧‧‧Inner diameter of main 1

D2‧‧‧The inner diameter of the upper branch tube 2

G2‧‧‧ molten glass

Height of Hm‧‧‧Supervisor 1 (length)

H‧‧‧ Distance from the upper end 1a of the main pipe 1 to the upper end Ja of the branch of the upper branch pipe 2

Ia‧‧‧ single phase alternating current

Ib‧‧‧ single phase alternating current

Ic‧‧‧ single phase alternating current

Upper end of the Ja‧‧ branch

Lower end of the Jb‧‧ branch

L‧‧‧The length of the upper branch tube 2

Claims (16)

A molten glass heating device includes a composite pipe structure through which molten glass passes and an electric heating unit that electrically heats the composite pipe structure, and the composite pipe structure includes a main pipe that is substantially horizontal with respect to a horizontal direction Vertically extending; an upper branch pipe from the main branch side of the upper portion of the main pipe; and a lower branch pipe from the main branch side of the lower portion of the main pipe; the electric heating portion includes an upper end of the main pipe a first electrode, a second electrode provided at a lower end of the main tube, and a third electrode provided at a side end of the upper branch pipe are formed to supply a current between the first electrode and the second electrode a first current supply path, and a second current supply path for supplying a current between the first electrode and the third electrode, and satisfying 0.4<(in the above-mentioned main tube) in the composite pipe structure a resistance of a current flowing between the upper end and the upper end of the branch portion, and a resistance of a current flowing between the branch portion of the upper branch pipe and the lateral end portion Total / currents flowing in the resistance between the upper end of the lower end of the above-described respective competent) mode <0.8, the branch pipe disposed above the upper competent. The molten glass heating apparatus according to claim 1, wherein in the composite pipe structure, when the upper branch pipe branches substantially perpendicularly from the main pipe, the height from the upper end to the lower end of the main pipe is set to Hm The inner diameter is D1, the length of the upper branch pipe is L, the inner diameter is D2, and the distance from the upper end of the main pipe to the upper end of the branch portion of the upper branch pipe is h. When to meet 0.4 < ((h / D1) + (L / D2)) / (Hm / D1) < 0.8, the above-mentioned upper branch pipe is disposed for the above-mentioned main pipe. The molten glass heating apparatus according to claim 1 or 2, wherein in the composite pipe structure, a minimum path of 0.55 < (the current flowing from the upper end of the main pipe to the upper end of the branch portion through the main pipe, and the above The total of the paths of the current flowing through the upper end of the inner peripheral portion of the upper branch pipe in the direction of the bus bar of the cylindrical upper branch pipe toward the side end of the upper branch pipe a shortest path of the current flowing to the lower end of the branch portion by the main pipe, and a direction from the bus bar of the upper branch portion of the upper branch portion of the upper branch pipe passing through the lower end portion of the upper branch pipe toward the upper branch pipe The upper branch pipe is disposed on the upper end of the main pipe so that the total of the paths of the currents flowing through the side ends is <0.77. The molten glass heating apparatus according to claim 1 or 2, wherein, in the composite pipe structure, when the upper branch pipe branches substantially perpendicularly from the main pipe, the length of the upper branch pipe is set to L, and the inside is When the diameter is D2, the distance from the upper end of the main pipe to the upper end of the branch portion of the upper branch pipe is h, and 0.55<(h+L)/(h+(5/4)D2+ is satisfied. In the manner of L) < 0.77, the upper branch pipe is disposed on the upper end of the main pipe. The molten glass heating apparatus of claim 2, wherein a height Hm from the upper end to the lower end of the main pipe is 500 mm to 3000 mm. The molten glass heating device of claim 2, wherein the upper branch pipe has a length L of 50 mm to 1500 mm. The molten glass heating apparatus of claim 2, wherein the inner diameter D1 of the main pipe is 50 mm to 500 mm. The molten glass heating device of claim 2, wherein the upper branch pipe has an inner diameter D2 of 50 mm to 500 mm and is shorter than one half of the height Hm of the main pipe. The molten glass heating apparatus of claim 2, wherein a distance h from an upper end of the main pipe to an upper end of the branch portion of the upper branch pipe is 50 mm to 500 mm, and is shorter than one half of the height Hm of the main pipe. The molten glass heating apparatus according to claim 1 or 2, wherein the energization heating unit includes a current balancing mechanism that adjusts a current flowing in the first current supply path and the second current supply path. The molten glass heating apparatus according to claim 10, wherein a first power source is provided in said first current supply path, a second power source is provided in said second current supply path, and said current balancing means is for said first power source and said second power source The phase of the current is adjusted. A molten glass heating apparatus according to claim 10, comprising: a fourth electrode provided at a side end portion of the lower branch pipe; and the second electrode and the fourth electrode provided to supply the current to the lower end of the main pipe The third current supply path between the electrodes adjusts a current flowing through the first current supply path, the second current supply path, and the third current supply path. The molten glass heating apparatus according to claim 1 or 2, wherein the composite pipe structure is made of platinum or a platinum alloy. A glass manufacturing apparatus comprising the molten glass heating apparatus according to any one of claims 1 to 13. The glass manufacturing apparatus according to claim 14, wherein the glass manufacturing apparatus includes a first molten glass heating apparatus and a second molten glass heating apparatus comprising the molten glass heating apparatus, and the lower part of the first molten glass heating apparatus The branch pipe is introduced into the pipe on the inlet side of the molten glass, and in the second molten glass heating device, the lower branch pipe is a pipe on the outlet side where the molten glass is discharged, and the side end portion of the upper branch pipe is It is disposed to face the side end portion of the upper branch pipe of the first molten glass heating device. A method for producing a glass article, which comprises the use of a glass manufacturing apparatus according to claim 14 or 15, and comprising the steps of: heating a glass raw material to obtain molten glass; and forming the molten glass and slowly cooling to obtain a glass article .