JP2003292323A - Glass-fusing furnace and glass-fusing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass-fusing furnace capable of corresponding to the big change of glass drawing amount when glass is continuously fused and a glass-fusing method. <P>SOLUTION: The glass-fusing furnace has such a shape that the area of the liquid level of fused glass in a fusing vessel 10 increases in the upward direction and is equipped with an electrode 12 whose contact area with the fused glass G can be controlled, a controlling gate 13 to control the flow rate of the fused glass G in a working vessel 30 or a feeder 40 or a forming vessel, and a glass raw material feeder 11 whose feeding port position can be controlled correspondingly to the level position of the fused glass G. The fusing method which uses the glass fusing furnace increases or decreases the glass drawing amount by controlling the contact area of the electrode 12 with the fused glass G correspondingly to the increase or decrease of the amount of glass held in the fusing vessel and by controlling the gate 13. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a glass melting furnace and a method for melting glass used in the glass melting furnace.

[0002]

2. Description of the Related Art In the glass manufacturing industry, volatile components, scattered components, reaction gases, etc. generated from raw materials during the melting of glass cannot be contained in the furnace and cause environmental pollution outside the furnace. For this reason, a glass melting method has been adopted in which the surface temperature of the glass raw material is kept low by coating the surface of the molten glass with the input glass raw material to prevent scattering and volatilization. This method is called the "cold top method". In addition to the above-mentioned effects of scattering and volatilization prevention, it has high thermal efficiency, it is easy to control the glass composition due to little volatilization, there is little air pollution, and work Due to its good environment, etc., it has been used extensively. Further, since zero emission is emphasized worldwide, and there is an increasing tendency to eliminate factors that hinder the environment such as air pollution as much as possible, it can be said that this method is an ideal glass melting method.

However, in this melting method, it is difficult to switch the glass type, and it is necessary to always keep the thickness of the raw material layer constant in order to keep the temperature of the molten glass constant. There are drawbacks such as difficulty in adjustment. In addition, this melting method is that the melting reaction gas is liable to be insufficiently defoamed because the surface of the melting tank is low in temperature, and because the heat source is limited, the flow of the molten glass once changes from the normal normal flow state. It has been found that it is difficult to control the molten glass temperature conditions and the like to return to the original normal flow state when disturbed.

Various inventions have been made in order to overcome the above problem of the "cold top system".
To keep the thickness of the raw material layer in the melting tank constant, select the raw material feeder, change the charging method, measure the raw material level after charging,
For example, there are forced air cooling or water cooling of the raw material surface temperature of the input raw material. Further, in order to homogenize the glass after melting, the electrode arrangement is changed, forced stirring blades are introduced, and the design of the structure of the melting tank is changed.

[0005]

However, in the above-mentioned melting method, there is a high possibility of causing a large variation in the thickness of the raw material layer described above with respect to the glass withdrawal amount, so that it is possible to change the withdrawal amount. Only within a very limited range. If the rate of decomposition of the raw material at a high temperature, which is limited by the rate of decomposition of the hardly soluble components such as silica and zirconia, and the rate of charging the raw material into the melting tank are not balanced, the thickness of the raw material layer added This is not the case. Stable production cannot be realized unless the thickness of the raw material layer is constant. That is, if the raw material input amount is increased in order to increase the extraction amount, it is necessary to improve the decomposition and melting rate of the raw material with the same raw material configuration, and if the raw material layer becomes too thick, the amount of sinking into the molten glass due to its own weight will increase. growing. As a result, there is a possibility that unmelted glass that has not been sufficiently decomposed flows out to the downstream side, reaches the molding region, and is molded as a glass defect. On the other hand, on the contrary, if the amount of the raw material input is not enough to meet the decomposition reaction rate and the raw material layer becomes too thin, the surface temperature on the raw material layer rises and the softening of the raw material surface causes the raw material surface It is easy to cause the collapse and delivery of. As a result, the unmelted raw material is also mixed in the molten glass, which causes a glass defect. At the same time, there is a high risk that the incidental equipment such as the raw material charging machine will be exposed to high temperature and volatile gas due to the increase in the amount of heat radiated from the surface of the molten glass, the amount of volatilization, etc. In terms of environmental protection, it is not desirable to cause an increase in volatile substances and scattered substances from the glass melting furnace.

Further, in order to keep the thickness of the glass raw material layer constant while increasing or decreasing the glass withdrawal amount as necessary,
While increasing or decreasing the amount of raw material input, it is necessary to work to adjust the rate of decomposition of some raw material, that is, to increase or decrease the rate of temperature rise to match the increase or decrease in the rate of decomposition, and to balance both rates. However, such a drastic change in the furnace operating conditions causes an imbalance between the raw material input amount and the decomposition rate, which makes the furnace unstable. Also, when designing a glass melting furnace, the upper and lower limits of the temperature increase rate that is possible in terms of equipment are determined,
Naturally, the amount of raw material withdrawn will be limited.

An object of the present invention is to enable flexible production because it is difficult to continuously produce glass products having the same specifications in the recent market trend where demand fluctuations are remarkable. In other words, it is required for the glass production by the glass melting furnace to adjust the production amount promptly in response to the market trend that changes day by day. Specifically, the glass melting furnace and its melting furnace that realize it are required. It is an object of the invention to provide a method of melting the glass used.

[0008]

In view of such a situation, the inventors of the present invention can appropriately produce a required amount, and have less soot and volatile matter, which is a so-called environment-friendly glass melting furnace. And a glass melting method that enables production of high-quality glass products by using this glass melting furnace.

That is, the glass melting furnace of the present invention is configured so that a glass raw material is charged into a molten glass, a working tank connected to the melting tank via a throat, and a feeder to the working tank. In a glass melting furnace having a molding tank connected thereto, the melting tank has a shape in which the area of the liquid surface of the molten glass increases upward, and has an electrode capable of adjusting the contact area with the molten glass. In addition, any one of the working tank, the feeder, and the molding tank is provided with a gate for adjusting the flow rate of the molten glass.

Here, the shape of the inside of the melting tank may be any shape as long as the area of the liquid surface of the molten glass staying in the melting tank increases upward. Absent. It is more preferable that the area of the liquid surface has a shape that continuously increases upward because control is easy to perform. That is, specifically, the shape of the inside of the melting tank is preferably a shape in which a horizontal surface having a small area of a polygonal frustum and / or an elliptical frustum is the hearth surface of the melting tank. Also, as the shape of the inside of the melting tank,
A polygonal pyramid and / or a plurality of polygonal pyramids and / or a part of the side surface of a cone are joined so as to be embedded in a surface contact with a part of a side surface of a melting tank having an elliptic cylinder and / or a polygonal cone, and / or an elliptic cone It is also possible to adopt a complex shape in which the apex side of the is arranged on the side surface closer to the bottom surface side of the polygonal prism or the polygonal prism than the bottom surface side of the pyramid or the elliptical cone. That is, when the melting tank is viewed in a horizontal cross section as a whole inside the melting tank, there is no problem as long as the shape of the melting furnace hearth area is the minimum area and the cross-sectional area increases as it goes upward. Also, the side surface of the melting tank does not necessarily have to be formed by a straight line such as a cone or a polygonal pyramid,
Any curve such as an arc or a parabola that gradually increases the horizontal cross-sectional area of the melting tank can be used.

However, from the economical point of view, when a simpler structure is adopted, a quadrangular truncated pyramid shape having a smaller area toward the bottom is adopted and the inclination angle of the side surface is 10 ° to 8 °.
It is set to 0 °. Alternatively, there may be a case where only a part of one side surface of the quadrangular prism is inclined, the bottom area corresponding to the hearth is minimized, and the horizontal sectional area of the melting tank increases as it goes upward.

The electrode whose contact area with the molten glass can be adjusted is based on information from a level meter that detects the volume of the molten glass staying in the melting tank, while maintaining the energized state. Forcibly change the amount of electricity and heating conditions by evacuating the electrode part immersed in the molten glass into the molten atmosphere gas, refractory in the melting tank, etc., or by immersing it deeper into the molten glass from the retracted state. It is an electrode that can be changed. Specifically, the shape of the electrode can be various shapes such as a rod shape and a plate shape. In the case of a rod shape, a cross-sectional shape such as a prism or a column is adopted as necessary. Further, as the material used for the electrode immersed in the molten glass, a heat resistant material such as molybdenum, platinum, platinum-rhodium alloy, tin oxide or the like is used.

As a method of arranging the electrodes, in the case of a rod-shaped electrode, the electrode is held by a cylindrical refractory whose inside is air-cooled or water-cooled. The electrode that passes through the inside of the cylinder of the tubular refractory penetrates the refractory and is inserted into the molten glass from the outside of the melting tank. Since the glass between the electrode and the refractory cylinder is in a state of being cooled and solidified by the water cooling or the air-cooling medium in the cylinder, the molten glass does not leak out of the furnace. When the electrode is inserted through the raw material layer,
The tubular refractory that holds the electrode in order to prevent it from being unable to maintain the "cold top" state due to local melting of the raw material layer around the electrode will utilize its water cooling and air cooling effects. .

On the other hand, in the case of a plate-shaped electrode, a method of using a tubular refractory having elongated holes similar to those of a rod-shaped electrode in the melting tank refractory, or a raw material layer penetrating along the inner wall of the melting tank refractory Similarly, there is a method of immersing in molten glass. In the latter case, the side in contact with the raw material needs to be protected with a water-cooled or air-cooled refractory. Also molten glass species,
Both the rod-shaped electrode and the plate-shaped electrode may be used at the same time depending on the structure of the melting tank, the extraction amount, etc., and a plurality of methods may be used in combination as the disposing method.

Regarding the arrangement of the electrodes in the melting tank, the electrodes are appropriately arranged and used at a plurality of necessary positions in the melting tank. That is,
It may be inserted into the molten glass through the insertion hole of the refractory material on the side wall of the melting tank, or may be similarly inserted through the refractory material hole of the hearth. Further, it is also possible to design such that the electrodes are used by arranging them so that they are suspended from above the raw material layer. Depending on the type of molten glass, when melting a material that has a large change in viscosity with respect to temperature changes in the melting temperature range, a so-called "short" material, the viscosity of the molten glass decreases sharply with increasing temperature. When inserting an electrode from the hearth, there is a high risk of the molten glass material leaking between the electrode and the electrode insertion hole.Therefore, the electrode should be inserted into the molten glass from above the melting tank or from the side wall. desirable.

The method of connecting to the electrodes can be selected as required, such as single phase, two phase (Scott connection), three phase (delta connection), and six phase. Further, since the temperature coefficient of the specific resistance of the molten glass is negative, it is necessary to suppress the local rise in temperature. Therefore, a supersaturation reactor, an induction voltage regulator, a thyristor, etc. are used as the voltage regulator.

As an electrode insertion method for increasing or decreasing the contact area with the molten glass, for example, in the case of a rod-shaped electrode from the side wall of the melting chamber, it is cooled and solidified between the rod-shaped electrode and the surrounding cylindrical refractory. In order to warm the glass being heated, the circulation of the cooling medium circulating in the cylinder is stopped, or the circulation speed is slowed to increase the temperature in the cylinder, thereby allowing the glass to soften and flow, and the optimum viscosity. By applying an external force in the direction of inserting or withdrawing the electrode at, the surface area of the electrode surface in contact with the molten glass is increased as necessary.

The gate for adjusting the flow rate of the molten glass is for adjusting the flow rate of the molten glass so as to reflect the change in the withdrawal amount of the molten glass.
By adjusting the amount of glass raw material charged and the surface area of the electrode immersed in the molten glass, the balance of the operating state of the entire glass melting furnace is adjusted appropriately.

Further, with respect to the gate for adjusting the flow rate of the molten glass, a plurality of gates may be installed if necessary. For example, by arranging them in series with respect to the flow direction of the molten glass, the first gate roughly adjusts the flow rate, and the second gate finely adjusts the flow rate. Also, in a glass melting furnace with multiple feeders, by arranging one gate in parallel for each feeder, it is possible to make detailed correspondence such as producing different types of different feeders with different production volumes. It also has the advantage that production can be performed according to the demand for each molding type.

Although the gate is generally installed in the feeder, it may be installed in the working tank or the molding tank as required. In addition, in order to prevent the phenomenon that the gate is pushed and moved by the flow of molten glass and that the flow of molten glass in the vicinity changes due to the movement of the gate and abnormal erosion of surrounding refractories occurs, It is necessary to fix it in place. For this purpose, the refractory around the gate may be provided with a recess to fix the gate, or a heat-resistant rail may be provided in the furnace so that the gate operates along the rail. Further, the gate used in this case does not necessarily have to be a flat plate shape, and when the structural strength at high temperature is particularly problematic, an arched gate having a convex shape on the upstream side with respect to the glass flow direction may be used. Of course, in order to maintain the laminar flow state, a gate having a streamlined cross-section that avoids unnecessary Karman vortices in the molten glass generated in the molten glass flow may be used.

Further, as the refractory used for the gate,
Various refractory materials are selected and used depending on the glass material to be melted, heat resistance and durability. That is, as the fired brick, silica stone brick, clay refractory brick, high alumina brick,
Silicon carbide refractory bricks, magnesia bricks, chrome bricks, dolomite bricks, mullite bricks, cyanide compound alumina bricks, sillimanite bricks, zirconia bricks, and alundum bricks are appropriately selected. Further, as the non-fired brick, graphite brick, silicon carbide graphite brick, high alumina brick,
Use castable refractories, plastic refractories, refractory mortar, etc. as needed as irregular refractories. Further, fused silica bricks, various fiberboards, and amorphous refractory fiber materials are also used as needed, and it is general to use a plurality of these materials together in order to maintain the structural strength.

Since the erosion of the gate immersed in the hotter molten glass by the molten glass remarkably affects the adjustment of the glass withdrawal amount, a heat-resistant noble metal such as platinum, etc., is applied to the part of the gate which is particularly liable to be eroded or the entire gate. By having a structure covered with a highly corrosion resistant material,
In many cases, the glass flow rate is stabilized.

Further, the glass melting furnace of the present invention is characterized in that, in addition to the above-mentioned features, a glass raw material charging machine capable of adjusting a charging port position in accordance with the position of the liquid surface of the molten glass is additionally provided. Is.

In the present invention, the raw material feeder whose inlet position is adjustable is a raw material feeder whose raw material feeding position can be changed up and down by measuring the level of the molten glass in the glass melting tank. It is appropriate for the glass material and raw material composition. For example, when a single or a plurality of screw feeders, vibration feeders, blanket feeders, oscillation batch feeders, etc. are arranged, it is advisable to fix the base portion of the charging section on an electric jack that can be changed up and down. If necessary, a plurality of glass raw materials having different particle sizes and properties, or the glass raw material and the glass cullet may be charged by different raw material charging machines.

The raw material may be fed by the raw material feeding machine not only in the vertical position depending on the structure of the melting tank but also in the front-back and left-right directions depending on the structure of the melting tank. The raw material feeding machine preferably has an adjusting function of appropriately changing the raw material feeding speed based on the information on the amount of stay in the melting tank. As a method of detecting or predicting the staying amount of the molten staying layer, information from the measurement of the liquid level of the molten glass, the measurement result of the glass withdrawal amount, the glass flow rate change information by the gate that adjusts the molten glass flow rate, the electrode insertion amount Change information, a method of determining in consideration of single information or composite information such as temperature measurement information of the melting tank,
It is a so-called "expert system", but it is also possible to use approximation results from numerical analysis similar to it.

In the glass melting method of the present invention, a glass raw material is charged into a melting tank to form molten glass, and the molten glass is clarified in a working tank connected through the throat,
In a method for melting glass, which is connected to the working tank via a feeder to bring molten glass to a predetermined molding viscosity in the molding tank, the melting tank has a shape in which a liquid surface area of the molten glass increases upward. , Having an electrode capable of adjusting the contact area with the molten glass, and either the working tank, the feeder or the molding tank has a gate for controlling the flow rate of the molten glass, and the molten glass liquid level in the melting tank It is characterized in that the contact area of the electrode with the molten glass is adjusted in accordance with the position of and the amount of glass pulled out is increased or decreased by adjusting the gate.

That is, according to the glass melting method of the present invention, the molten glass retention amount in the melting tank, the opening amount of the gate for adjusting the flow rate of the molten glass, the surface area of the electrode capable of adjusting the contact area with the molten glass, and the glass drawing. It is a method of heating glass raw material or molten glass from the viewpoint that each change becomes another fluctuation factor for each amount, and it functions as a system constructed so that these elements work in balance with each other. It is a thing. Among them, when the glass is melted using the above-mentioned glass melting furnace of the present invention, the surface area of the electrode capable of adjusting the opening area of the gate for adjusting the flow rate of the molten glass and the contact area with the molten glass, the melting Adjustment of the three factors of the molten glass retention amount in the tank is indispensable. However, the detailed mutual relations of the three elements are not always the same because they are influenced by the shape of the glass melting furnace to be used, the volume, the arrangement position of the electrodes, and the like.

In addition to the above characteristics, the glass melting method of the present invention is characterized in that the contact area of the electrode with the molten glass is adjusted based on the measurement value of the molten glass by a minute voltage detecting device or a minute current detecting device. And

Here, as the measurement by the minute voltage detecting device or the minute current detecting device for realizing the present method, a measuring system using a heat resistance detecting terminal is used, and a slight change in voltage or current is detected. The device is not particularly limited as long as it has a configuration capable of achieving the above. In addition, this system has a cohesive function as a whole while considering the measurement result information from the temperature measuring system of the melting tank.

In the method of the present invention, the melting rate of the raw material layer in the melting tank is changed by changing the contact area between the electrode and the molten glass based on the value measured by the minute voltage detector or the minute current detector. To adjust. this is,
By detecting a minute voltage or current change near the electrode, accurately grasping the state of the glass in the vicinity, and adjusting the contact area between the electrode and the molten glass to achieve an appropriate molten glass melting result. By feeding back to other factors, that is, the adjustment of the gate opening amount and the raw material input amount, stable glass melting is realized.

Further, in the present invention, as the heat source installed in the melting tank, it is desirable to use only electricity as the heat source, but the arrangement position of the electrode to be used is not limited.
That is, it is not necessary that all the electrodes be immersed in the molten glass, and an indirect heating method or the like may be used together if necessary. However, the use of combustion gas requires dust collection equipment, etc., which is not desirable from an economical and environmental perspective.
It should be avoided if possible. That is, the method of the present invention is
By using the cleanest heat source as the heat source, the glass production environment can be kept clean, and large fluctuations in the production amount can be dealt with.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION The glass melting furnace and the method for melting molten glass of the present invention will be described in detail below with reference to specific examples.

Example 1 A glass melting furnace for producing glass fibers has a cross section as shown in FIG. Melting tank 1
At 0, two raw material feeders 11 for feeding glass raw materials that have been adjusted and mixed in advance are installed. This raw material charging machine 1
Reference numeral 1 denotes a belt conveyor type, which is computer-controlled for the function of vertically moving the raw material feeding point, and the raw material is continuously fed into the melting tank 10 by the feeding machine 11. At the tip of the conveyor, there is provided a guide fitting for carrying the raw material to a position close to the surface of the glass raw material layer S in order to prevent the raw material from being scattered and separated during the spraying of the raw material. The charged raw material is deposited in the melting tank 10 as the glass raw material layer S above the glass layer K in the melting tank. Then, the molten glass G heated by the movable electrode 12 and melted, and the vitrification reaction is completed, flows into the working tank 30 through the throat 20, and then the molten glass G is melted by the gate 13 arranged in the feeder 40. The flow rate is narrowed down,
Finally, it is drawn out in the molding zone and molded into a predetermined shape.

Here, the melting tank 10 has a structure in which the horizontal area becomes smaller toward the bottom surface of the melting tank, and the side wall of the melting tank 10 has an inclination angle of 45 °. Further, ten columnar electrodes 12 having a diameter of 10 cm arranged in the melting tank 10 are inserted into the molten glass G on the left and right sides, and a constant current that makes the current values of the constant power control device and each electrode equal in a single phase. It is equipped with a control device. The 10 pairs of electrodes 12 are held in water-cooled cylinders 14, respectively.
The height of the melting tank 10 is 4.5 m from the ceiling to the bottom refractory.
And the dimensions of the throat 20 are 300 mm x 600 mm x
The feeder 40 connected to the working tank 30 having a volume of 1.5 m and a volume smaller than that of the melting tank 10 has an inner width of 600 mm and a length of 4 m.
It has become. The gate 13 for adjusting the flow rate of the molten glass G has a structure in which the outer periphery of the alumina refractory material is covered with a platinum plate. As shown in FIG. 2, the gate 13 is a refractory material 15 in which a feeder 40 has a depression.
Since the molten glass G is fixed, the molten glass G does not flow under pressure.

A glass melting method for increasing the glass production from 15 to 30 tons a day by using the glass melting furnace will be described. When increasing the production, the electric power of 1200 kw was input to melt the glass. In order to double the amount of raw material input from the production of 15 tons per day, the raw material input amount is gradually increased until the liquid level of the molten glass G in the melting tank 10 rises. Then, the area of the liquid surface becomes large, and accordingly, the electrode insertion amount is gradually inserted in six stages at any time, thereby increasing the contact area with the molten glass G and dealing with the increase in the melting amount. At the same time, the gate 13 for adjusting the flow rate of the molten glass G
The opening was gradually opened, and finally a withdrawal amount of 30 tons could be realized. At this time, the working tank 3
There was a 2 m drop between the level of the molten glass liquid level of 0 and the level of the molten glass liquid level in the feeder 40 behind the gate 13. The feed point of the raw material feeder 11 is
By raising the glass raw material layer S at any time,
Raw materials were introduced without scattering of raw materials. Also,
A comparison of the glass quality when producing 15 tons per day and the glass quality when producing 30 tons per day shows that, in the past, air bubbles, foreign substances, etc., increased temporarily or permanently, but deteriorated completely. It was possible to maintain a stable high glass quality regardless of the production volume.

(Example 2) An example of the present case will be described for a small continuous electric melting furnace for producing optical parts. FIG. 3 shows a partial side cross section of an electric melting furnace for producing a glass for micro optical components. The melting tank 10 has a viscous property that the glass composition to be melted is very short. Therefore, when the electrode is charged from below, when the contact amount of the electrode capable of adjusting the contact area with the molten glass G is adjusted, There is a problem that molten glass dough leaks from the vicinity. Therefore, the electrode 12 is disposed so as to be inserted from the glass raw material layer S side, that is, from above. Further, in the electric melting furnace of the present invention, the volume of molded glass needs to be adjusted very precisely, so that it is necessary to precisely adjust the outflow amount of glass when performing high-definition press molding. Therefore, the gate 1 for adjusting the flow rate of the molten glass G
Regarding No. 3, two-step control is performed to enable precise adjustment of the glass flow rate. That is, first, 1 on the working tank side
The flow rate of the molten glass G was roughly adjusted at the second gate 13a, and then the second gate 13 near the molding part.
For b, the flow rate during press molding is finely adjusted. Further, the raw material charging machine employs a screw charger 11 instead of a belt conveyor, and is connected to an electric lifting device capable of vertically changing the charging point. Then, the cooperation of these series of systems is controlled by computer control.

(Embodiment 3) FIG. 4 shows an example in which the glass heating method of the present invention is adopted in a glass melting furnace for continuously producing thin glass used in electronic parts and the like. The shape of the melting chamber 10 is a prismatic shape in which the side wall of the throat 20 is provided with an inclination, and the area of the molten glass liquid surface continuously increases as it goes upward in the melting tank. In addition, a belt conveyor type raw material feeder 11 is used for the melting tank 10.
I have a stand. Further, a bubbling hole 17 is provided in the working chamber 30, and the homogenized molten glass G flows out to the forming part after the flow rate is adjusted by the gate 13 which adjusts the flow rate of the molten glass by the feeder 40. Since this melting furnace has a volume (1 ton) that is about 5 times that of the small-sized furnace for optical parts described above, the structure of the melting chamber is simplified as much as possible, and the melting chamber is constructed by the throat slope. It has a structure that regulates the shape. Further, an indirect heating electrode 16 is also arranged in the working chamber so that a sufficient amount of heat can be given to the molten glass.

[0038]

According to the glass melting furnace and the glass melting method of the present invention, the thickness of the glass raw material layer on the glass melt is always optimized even when the production amount is largely changed and the glass melting amount is greatly changed. It is possible to perform melting in a state where it is maintained in such a state, and it is possible to supply a required amount of high-quality glass products to the market.

[Brief description of drawings]

FIG. 1 is a partial side sectional view of a glass melting furnace of the present invention.

FIG. 2 is a partial plan view of the glass melting furnace of the present invention.

FIG. 3 is a partial side sectional view of another glass melting furnace according to the present invention.

FIG. 4 is a partial side sectional view of another glass melting furnace according to the present invention.

[Explanation of symbols]

10 melting tank 11 Raw material feeder 12 electrodes 13 Gate for adjusting the flow rate of molten glass 14 Insertion guide 15 Recessed refractories 16 Indirect heating electrode 17 bubbling hole 20 throat 30 working tanks 40 feeder S glass raw material layer K glass layer G molten glass

Claims (4)

[Claims] 1. A melting tank for charging glass raw material into molten glass, a working tank connected to the melting tank via a throat, and a forming tank connected to the working tank via a feeder. In the glass melting furnace, the melting tank has a shape in which the area of the liquid surface of the molten glass increases upward, has an electrode whose contact area with the molten glass can be adjusted, and a working tank, a feeder or A glass melting furnace comprising a gate for adjusting the flow rate of molten glass in any of the forming tanks. 2. The glass melting furnace according to claim 1, wherein a glass raw material charging device capable of adjusting a charging port position according to a position of a liquid surface of the molten glass is attached to the melting tank. 3. A molding tank connected to the working tank via a feeder, wherein a glass raw material is charged into the melting tank to form molten glass, the working glass connected from the melting tank via a throat clarifies the molten glass. In the method for melting glass to make the molten glass have a predetermined molding viscosity, the melting tank has a shape in which the area of the liquid surface of the molten glass increases upward, and the contact area with the molten glass is adjustable. The working tank, any one of the feeder and the molding tank has a gate for adjusting the flow rate of the molten glass, and the electrode is brought into contact with the molten glass in accordance with the position of the liquid surface of the molten glass. A glass melting method characterized in that the amount of glass drawn out is increased or decreased by adjusting the area and the gate. 4. The glass melting method according to claim 3, wherein the contact area of the electrode with the molten glass is adjusted based on the measurement value of the molten glass by the minute voltage detecting device or the minute current detecting device.