WO2007108324A1

WO2007108324A1 - Glass melting method and glass melting furnace

Info

Publication number: WO2007108324A1
Application number: PCT/JP2007/054424
Authority: WO
Inventors: Kimio Iino; Shinji Murakami
Original assignee: Taiyo Nippon Sanso Corporation; Ohara Inc.
Priority date: 2006-03-16
Filing date: 2007-03-07
Publication date: 2007-09-27
Also published as: JP5231211B2; CN101400612A; MY177056A; CN101400612B; JPWO2007108324A1

Abstract

In a glass melting method, a glass melting furnace having a melting tank is used, an adjusting tank is arranged in the downstream of a melting glass flow in the melting tank, equilibrium state of water concentration on an interface between an ambient gas and a melting glass surface is controlled by adjusting the temperature of the adjusting tank and a quality of a gas to be introduced into the adjusting tank.

Description

Specification

Glass melting method and glass melting furnace

Technical field

TECHNICAL FIELD [0001] The present invention relates to a glass melting method and a glass melting furnace for efficiently manufacturing a glass product in the manufacture of a glass product using oxyfuel combustion.

This application claims priority based on Japanese Patent Application No. 2006-72235 filed in Japan on March 16, 2006, the contents of which are incorporated herein by reference.

Background art

[0002] In recent years, in a glass melting furnace for industrially producing glass, oxygen combustion has been increasingly used for glass of a type that requires high-temperature melting (Patent Documents 1 to 3). . In particular, when melting glass that requires high-temperature melting in a batch-type melting furnace such as a detank furnace, oxyfuel combustion is often employed because air combustion has low thermal efficiency.

[0003] By the way, if oxygen combustion is used for high-temperature melting of glass, the combustion gas contains a large amount of carbon dioxide and water, and there is a concern that the moisture concentration in the glass will increase. Water is incorporated into glass as OH groups Depending on the type of glass, such as high-purity silica glass and non-alkali glass, this high OH group content affects the glass structure, and the subsequent process. The product yield may be adversely affected, and there is a concern that the product yield may be reduced. This moisture concentration may vary depending on the season, and it is complicated to optimize the moisture concentration adjustment in the latter stage of glass melting.

[0004] Patent Document 4 discloses a method of adjusting the moisture concentration in a gas in a glass melting furnace. The purpose of this method is to install a humidifier outside the secondary air so that the air supplied to the melting furnace is humidified and maintained at a constant humidity to prevent temperature fluctuations in the melting furnace. This method increases the water vapor concentration in air combustion. On the other hand, in oxygen combustion, water is generated more than three times as much as in air combustion, so the method described in Patent Document 4 adjusts the moisture concentration in glass by adjusting the moisture concentration in the gas as described above. Can not do.

[0005] When oxygen combustion is employed as a heat source in a glass melting furnace, There is a need for a melting method and a furnace that can properly control the degree.

Patent Document 1: JP-A-6-24752

Patent Document 2: JP-A-10-316434

Patent Document 3: Japanese Patent Laid-Open No. 11_11954

Patent Document 4: JP-A-8_268724

Disclosure of the invention

Problems to be solved by the invention

[0006] An object of the present invention is to provide a glass melting method and a glass melting furnace capable of adjusting the moisture concentration in the glass even when the oxygen combustion method is used as a glass melting heat source in the glass melting furnace. There is to do.

Means for solving the problem

[0007] In order to solve the above problems, the present invention is a glass melting method using a glass melting furnace provided with a melting tank, wherein an adjusting tank is disposed downstream of the molten glass flow in the melting tank, and the adjusting tank Glass melting method that adjusts the moisture concentration in the molten glass by controlling the equilibrium state of the moisture concentration at the interface between the atmospheric gas and the molten glass surface by adjusting the temperature of the gas and the amount of gas introduced into the adjustment tank I will provide a.

[0008] In the present invention, since the effect is particularly great when the raw glass is melted using an oxygen burner, the present invention is applied when the raw glass is melted using an oxygen burner in the melting tank. Is preferred. Further, in order to appropriately adjust the water concentration in the molten glass, it is preferable to keep the pressure in the adjustment tank at a positive pressure.

[0009] Further, the present invention is a glass melting furnace for melting a raw glass as a glass melting furnace for carrying out the glass melting method, the melting tank and the moisture of the glass melted in the melting tank An adjustment tank for adjusting the concentration, a throat part for flowing molten glass to the melting tank force adjustment tank, and a partition wall for isolating the upper space of the melting tank and the upper space of the adjustment tank, The adjustment tank provides a glass melting furnace provided with a partition weir provided downstream of the molten glass flow from the partition wall, a molten glass heating means for adjusting the molten glass temperature, and an atmospheric gas inlet. .

[0010] The present invention is particularly effective in a melting furnace equipped with an oxygen burner. Therefore, it is preferable to apply the present invention in a melting furnace in which the melting tank includes an oxygen burner.

The molten glass heating means is preferably a submerged electrode and / or an electric heater.

Furthermore, it is preferable that the adjustment tank is provided with an atmospheric gas heating means for adjusting the temperature of the atmospheric gas. The atmospheric gas heating means is preferably an electric heater.

The invention's effect

[0011] According to the present invention, in the glass melting furnace, the adjustment tank is provided downstream of the molten glass flow in the melting tank to adjust the water concentration in the molten glass. Therefore, the oxygen combustion method is used as the glass melting heat source. In addition, the water concentration in the molten glass can be properly managed.

Brief Description of Drawings

FIG. 1 is a cross-sectional view of a glass melting furnace for carrying out the present invention.

Explanation of symbols

[0013] 1 Glass melting furnace, 2 Melting tank, 3 Adjustment tank, 4 Partition wall, 5 Throat section, 6 Cutting weir, 7 Adjusting bath, 8 · Oxygen burner · · · Atmospheric gas inlet, ··· Electric heater, ··· Immersion type electrode, ··· Glass outlet, ··· 22 ··· Raw glass · ··· Molten glass Best form for

[0014] An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view schematically showing a melting furnace suitable for carrying out the present invention. As shown in the figure, the melting furnace 1 has a melting tank 2 and a regulating tank 3. The upper space of the melting tank 2 and the adjustment tank 3 is isolated by a partition wall 4.

The raw material glass 22 in the raw material hopper 20 is put into the melting tank 2 by the raw material feeder 21. The raw glass 22 is melted by a plurality of oxygen analyzers 8, 8... Installed in the melting tank 2, and sequentially becomes a molten glass 23. The molten glass 23 is introduced into the adjustment tank 3 through the slot portion 5 below the partition wall 4. The adjustment tank 3 is provided with a partition weir 6, and the molten glass 23 overflows the partition weir 6 and is stored in the adjustment bath 7. original The charge is supplied until the amount of accumulated glass in the adjustment bath 7 reaches a predetermined level.

[0016] In the upper space of the adjustment tank 3, an atmospheric gas inlet 10 for adjusting the moisture concentration in the gas phase is provided. By introducing dry nitrogen gas or the like from the atmosphere gas inlet 10 and lowering the moisture concentration in the atmosphere gas to be lower than the moisture concentration in the molten glass 23, the atmosphere gas is introduced into the glass at the surface of the molten glass 23 surface. The diffusion of moisture into the atmospheric gas is developed, and the moisture concentration in the glass is lowered. In addition, in the upper space of the melting tank 2 and the adjustment tank 3, a melting tank exhaust gas port 9 and an adjustment tank exhaust gas port 24 for leading out excess exhaust gas are provided, respectively.

[0017] In adjustment tank 3, in order to perform heat compensation of molten glass 23, it is preferable to provide a molten glass heating means. Specifically, heat compensation is performed by installing an electric heater 11 in the upper space of the adjustment tank 3, or by providing an immersion electrode 12 in the molten glass 23 and performing Joule heating. The electrode 12 is preferably made of platinum so as not to be eroded by the molten glass 23, but it is also possible to use molybdenum depending on the glass component. The adjustment tank 3 is preferably provided with an atmospheric gas heating means for adjusting the temperature of the atmospheric gas. Specifically, the electric heater 11 is mentioned.

[0018] Side walls of the partition weir 6 are inclined on both the throat portion 5 side and the adjustment bath 7 side, and the partition weir 6 has a shape that smoothly flows when the molten glass 23 overflows the partition weir 6. Is preferred. By providing the partition weir 6 having such a shape, the contact area with the atmospheric gas increases when the molten glass 23 flows down the side wall on the adjustment bath 7 side. For this reason, it becomes easier to adjust the water concentration, and the residence time in the adjustment bath 7 can be shortened.

[0019] Forcible stirring of the molten glass also enhances the moisture concentration adjustment effect. For this reason, a gas stirrer (not shown) is provided in the molten glass 23, or gas bubbling is performed by introducing a gas publishing gas from the gas publishing port 13. At this time, it is preferable that the moisture concentration of the gas bubbling gas is lower than the moisture concentration in the molten glass 23, similarly to the atmospheric gas. The atmosphere gas and gas publishing gas introduced into the adjustment tank 3 should be preheated by heat exchange with the combustion exhaust gas discharged from the melting tank 2. Heat exchange can reduce energy consumption.

[0020] The residence time of the molten glass 23 in the adjustment bath 7 varies depending on the type of glass and the amount of melting. Therefore, the volume of the adjustment bath 7 should be determined so as to ensure an appropriate residence time.

[0021] Once the molten glass 23 has been adjusted to the desired moisture concentration, the molten glass 23 in the adjustment bath 7 is allowed to flow out from the glass outlet 14 installed at the bottom or bottom of the adjustment bath 7 until the predetermined level is reached. Send to the next process. After the molten glass 23 flows out, the glass outlet 14 is closed again, and the raw glass 22 is put into the melting tank 2 again to start melting the glass. By repeating this operation, it is possible to produce a glass whose moisture concentration is properly controlled.

[0022] Continuous production is also possible when the adjustment bath 7 is enlarged and the outflow amount of the molten glass 23 is controlled to ensure a residence time for appropriately adjusting the moisture concentration. If the melting furnace 1 becomes too large, the batch type may be more energy efficient.

Example

[0023] (Example 1)

[0024] A melting test of soda-lime glass was performed. A melting furnace 1 having a melting amount of 2 tons / day and a volume of the adjusting bath 7 of 4 tons was used.

[0025] The raw glass 22 started to melt from the state where 50% of the molten glass 23 was stored in the adjustment bath 7, and the molten glass 23 was stored until a predetermined amount was obtained over 24 hours. During this time, for the purpose of heat compensation, the atmospheric gas temperature was adjusted by the electric heater 11 in the upper space and Joule heating was performed by the immersion type platinum electrode.

[0026] As the atmospheric gas, a dry nitrogen gas preheated by heat exchange with the combustion exhaust gas from the melting tank 2 was used. The preheating temperature was about 300 ° C. A restriction was provided at the exhaust gas port 24 for the adjustment tank so that the inside of the adjustment tank 3 was always kept at a positive pressure to prevent air from entering through the exhaust gas port 9 for the melting tank. After the introduction of the glass material 22 was stopped and the water concentration was adjusted while introducing nitrogen gas into the adjustment bath 7 for 24 hours, the amount of molten glass 23 in the adjustment bath 7 was reduced to 50 from the glass outlet 14. It was allowed to flow out until it reached%, and the glass was molded.

[0027] The process from the introduction of the raw material glass 22 to the outflow of the molten glass 23 is repeated three times, and three plate samples (a) to (c) are cut out from the molded glass obtained in each process, The moisture concentration was measured. The moisture concentration in the glass is measured by an infrared absorption test, using Lambert's law in the OH group infrared absorption band (2.8 μ · η, 3.6 μm). And identified from comparison with a standard sample.

[0028] The water concentration of the sample obtained in the first step was 400 to 500 ppm. The first process was excluded from the evaluation because it may be affected by the unsteady state up to 50% accumulation in adjustment tank 3. Table 1 shows the results of moisture measurements for the second sample 2 (a) to 2 (c) and the sample 3 (a) to 3 (c) obtained in the third step. The moisture content of the samples all decreased to around 200 ppm, that is, below 220 ppm, indicating that there was no need to adjust the moisture after the melting process.

[0029] (Comparative Example 1)

In the upper space of the adjustment tank 3, oxygen burners 8, 8,... Were installed in place of the electric heater 11 and the batch processing of the molten glass 23 was performed under the same conditions as in the examples. Three plate samples (C (a) to C (c)) were cut out from the obtained molded glass, and the water concentration was measured in the same manner as in the examples. The results are shown in Table 1. Samples C (a) to C (c) had a moisture concentration of around 700 ppm.

[0030] [Table 1]

Industrial applicability

In the present invention, even if an oxyfuel combustion system is used as a glass melting heat source, the water concentration in the molten glass 23 can be properly managed, so that it is not necessary to adjust the moisture at the latter stage of the melting process. Therefore, it is industrially useful.

Claims

The scope of the claims

[1] A glass melting method using a glass melting furnace provided with a melting tank,

An adjustment tank is placed downstream of the molten glass flow in this melting tank, and the equilibrium state of the moisture concentration at the interface between the atmospheric gas and the molten glass surface is adjusted by adjusting the temperature of the adjustment tank and the amount of gas introduced into the adjustment tank. A glass melting method having a step of controlling the water concentration in the molten glass.

[2] The glass melting method according to [1], wherein the raw glass is melted using an oxygen burner in the melting tank.

3. The glass melting method according to claim 1, wherein the adjustment tank is maintained at a positive pressure.

[4] A glass melting furnace for melting raw glass,

A melting tank;

An adjustment tank for adjusting the moisture concentration of the glass melted in the melting tank;

A throat section for flowing molten glass power molten glass to the adjustment tank;

A partition wall for isolating the upper space of the melting tank and the upper space of the adjustment tank,

The said adjustment tank is equipped with the partition weir provided in the downstream of the molten glass flow from the said partition wall, the molten glass heating means for adjusting a molten glass temperature, and an atmospheric gas inlet.

5. The glass melting furnace according to claim 4, wherein the melting tank comprises an oxygen burner.

6. The glass melting furnace according to claim 4, wherein the molten glass heating means is an immersion electrode and / or an electric heater.

7. The glass melting furnace according to claim 4, wherein the adjustment tank further includes an atmospheric gas heating means.

8. The glass melting furnace according to claim 7, wherein the atmospheric gas heating means is an electric heater.