JP2024076667A - Glass manufacturing method and glass manufacturing apparatus - Google Patents

Abstract

[Problem] To provide a glass manufacturing method that uses easily available orthoboric acid, while enabling reduction in energy consumption in the melting step, and avoiding the problem of a significant drop in the production volume of glass products per unit time. [Solution] The glass manufacturing method includes a preparation step of preparing glass raw materials, and a melting step of melting the prepared glass raw materials to produce molten glass. In the preparation step, metaboric acid is produced from orthoboric acid by utilizing exhaust heat from a glass manufacturing apparatus 11, and metaboric acid is included in the glass raw materials. [Selected Figure] Figure 1

Description

The present invention relates to a glass manufacturing method and a glass manufacturing apparatus.

The glass manufacturing method includes a melting step in which prepared glass raw materials are melted to produce molten glass. The glass raw materials include a silicon source and a boron source. Examples of boron sources include orthoboric acid, metaboric acid, and boric anhydride. For example, in Patent Document 1, by including boric anhydride, which has the lowest water content, in the glass raw materials, it is possible to suppress energy loss due to evaporation of water during the melting step.

International Publication No. WO 2009/054314

However, boric anhydride is difficult to obtain and very expensive. Metaboric acid, which contains less water than orthoboric acid, is also difficult to obtain and expensive compared to orthoboric acid. Orthoboric acid is easy to obtain and inexpensive, but contains a large amount of water, so there is a problem that the use of orthoboric acid results in a large energy loss in the melting process. In other words, when orthoboric acid is included as a boron source in the glass raw material, there is a problem that the energy consumption increases in order to melt the glass raw material normally. In addition, because orthoboric acid contains a large amount of water, foaming material is generated by the boron source during the initial melting process of the raw material. This foaming material inhibits the continuous batch feeding into the melting furnace, resulting in a significant decrease in the production volume of glass products per unit time (hereinafter referred to as the "flow rate").

The object of the present invention is to provide a glass manufacturing method and glass manufacturing apparatus that utilizes easily available orthoboric acid, while reducing energy consumption in the melting process and avoiding a significant decrease in flow rate.

[1] The method for producing glass that solves the above problem includes a preparation step of preparing glass raw materials, and a melting step of melting the prepared glass raw materials to produce molten glass, in which in the preparation step, exhaust heat from a glass production apparatus is used to produce metaboric acid from orthoboric acid, and the metaboric acid is included in the glass raw materials.

According to this method, metaboric acid is produced from orthoboric acid using exhaust heat from a glass manufacturing apparatus, so metaboric acid can be obtained from orthoboric acid, which is easily available, without consuming any additional energy. Since the glass raw material contains metaboric acid produced in the preparation process, energy consumption can be reduced in the subsequent melting process compared to, for example, when orthoboric acid is included in the glass raw material without using metaboric acid. In other words, the glass raw material can be melted normally with less energy. Therefore, energy consumption can be reduced while using orthoboric acid, which is easily available. Furthermore, since metaboric acid contains significantly less water than orthoboric acid, by using metaboric acid as a boron source, the generation of foam caused by the boron source can be suppressed in the initial stage of melting the raw materials in the melting process, and the problem of a significant decrease in flow rate can be avoided.

[2] In the method for producing glass according to the above [1], it is preferable that the exhaust heat is exhaust heat generated in the melting step.
According to this method, the exhaust heat is generated by utilizing the exhaust heat generated during the melting step in the manufacturing method, and therefore, for example, it is possible to reduce energy consumption in a single glass manufacturing apparatus without using another glass manufacturing apparatus.

[3] In the glass manufacturing method according to the above [1], it is preferable that the exhaust heat is exhaust heat from a melting step different from the melting step.
According to this method, the waste heat is utilized from a melting process separate from the melting process in the manufacturing method, so that, for example, even in a glass manufacturing apparatus in which it is difficult to utilize the waste heat, the energy consumption in the melting process can be reduced by using metaboric acid. Also, the problem of a significant decrease in the flow rate described above can be avoided.

[4] In the glass manufacturing method described in any one of [1] to [3] above, it is preferable that the exhaust heat is exhaust heat from the flue of any one of the melting furnace, the feeder, the forming section, and the annealer in the glass manufacturing apparatus.

According to this method, the exhaust heat is easily utilized because it is the exhaust heat of one of the flues of the melting furnace, the feeder, the forming unit, and the annealer in the glass manufacturing apparatus. For example, by partially modifying the structure of the flue originally equipped in the glass manufacturing apparatus, the exhaust heat can be utilized without requiring major structural modifications. In addition, since the temperatures of the melting furnace, the feeder, the forming unit, and the annealer are all different, the method can select an appropriate exhaust heat temperature, and the desired metaboric acid can be efficiently produced. As an example, when producing borosilicate glass, the temperature of the melting furnace is 1200 to 1500°C, the temperature of the feeder is 1300 to 1000°C, the temperature of the forming unit is 800 to 1000°C, and the temperature of the annealer is 600 to 800°C.

[5] In the glass manufacturing method described in [4] above, it is preferable to place a heat exchanger in the flue and transfer the thermal energy of the exhaust heat to a dryer that produces the metaboric acid via the heat exchanger.

According to this method, a heat exchanger is placed in the flue and the thermal energy of the exhaust heat is transferred via the heat exchanger to a dryer that produces metaboric acid, so the exhaust heat in the flue can be used efficiently. In other words, compared to a configuration in which the exhaust gas passing through the flue is directly directed at a dryer, for example, the thermal energy of the exhaust heat can be used more efficiently and the metaboric acid produced can be prevented from being contaminated by impurities contained in the exhaust gas.

[6] In the glass manufacturing method described in [5] above, it is preferable that the air that has passed through the inside of the heat exchanger is directly introduced into a drying container of the dryer and passed through the drying container.

According to this method, the air that has passed through the heat exchanger is fed directly into the drying container of the dryer and passes through the drying container, so that the moisture generated when metaboric acid is produced can be efficiently discharged to the outside of the drying container.

[7] In the glass manufacturing method described in [5] or [6] above, it is preferable to provide a branched exhaust section upstream of the heat exchanger in the flue, and to adjust the temperature around the heat exchanger by exhausting a portion of the exhaust heat from the branched exhaust section.

According to this method, a branch exhaust section is provided upstream of the heat exchanger in the flue, and a portion of the exhaust heat is exhausted from the branch exhaust section to adjust the temperature around the heat exchanger, so that, for example, the temperature around the heat exchanger can be prevented from becoming excessively high. Therefore, for example, the desired metaboric acid can be produced satisfactorily.

[8] In the glass manufacturing method according to the above [7], it is preferable to adjust the temperature around the heat exchanger by adjusting the exhaust amount of the branch exhaust section.
According to this method, the temperature around the heat exchanger can be adjusted by adjusting the exhaust volume of the branch exhaust section, so that, for example, the temperature around the heat exchanger can be appropriately adjusted to an optimal temperature. Therefore, for example, the desired metaboric acid can be more effectively produced.

[9] In the method for producing glass according to any one of [5] to [8] above, it is preferable that the metaboric acid is generated in a state in which the inside of the dryer is coated with the metaboric acid.

According to this method, metaboric acid is generated while the inside of the dryer is coated with metaboric acid, which, for example, prevents the generated metaboric acid from being contaminated with metal components that make up the dryer.

[10] In the method for producing a glass according to any one of the above [1] to [9], the metaboric acid is preferably a monoclinic crystal.
According to this method, the metaboric acid produced is a monoclinic crystal, so that the state is stable and easy to handle. In other words, when metaboric acid is an orthorhombic crystal, it is prone to absorbing moisture and is unstable, and when metaboric acid is a cubic crystal, it is prone to becoming sticky when produced and is difficult to handle, but these problems can be avoided.

[11] A glass manufacturing apparatus that solves the above problem includes a melting furnace that melts glass raw materials to produce molten glass, a flue for releasing exhaust heat to the outside, a heat exchanger disposed in the flue, and a dryer that is connected to the heat exchanger and produces metaboric acid from orthoboric acid using the thermal energy of the exhaust heat transferred through the heat exchanger.

According to this configuration, metaboric acid can be produced from orthoboric acid using exhaust heat, so metaboric acid can be obtained from orthoboric acid, which is easily available, without consuming any additional energy. Furthermore, if the produced metaboric acid is included in the glass raw material, the energy consumption in the melting process can be reduced compared to, for example, when orthoboric acid is included in the glass raw material without using metaboric acid. In other words, the glass raw material can be melted normally with less energy. Therefore, it is possible to reduce energy consumption while using orthoboric acid, which is easily available. In addition, the problem of a significant decrease in the flow rate described above can be avoided.

[12] In the glass manufacturing apparatus described in the above [11], it is preferable that a branched exhaust section is provided upstream of the heat exchanger in the flue.
According to this configuration, since a branched exhaust section is provided upstream of the heat exchanger in the flue, the temperature around the heat exchanger can be adjusted, and for example, the temperature around the heat exchanger can be prevented from becoming excessively high. Therefore, for example, the desired metaboric acid can be produced satisfactorily.

[13] In the glass manufacturing apparatus described in the above [12], it is preferable that the branch exhaust section has an adjustment valve capable of adjusting an exhaust amount.
According to this configuration, since the branch exhaust section has an adjustment valve capable of adjusting the exhaust volume, for example, the temperature around the heat exchanger can be appropriately adjusted to an optimal temperature by adjusting the exhaust volume of the branch exhaust section, and therefore, for example, the desired metaboric acid can be more effectively produced.

The glass manufacturing method and glass manufacturing apparatus of the present invention can reduce energy consumption in the melting process while using orthoboric acid, which is easily available. In addition, the problem of a significant decrease in the flow rate described above can be avoided.

FIG. 1 is a schematic plan view showing a glass manufacturing apparatus according to one embodiment. FIG. 2 is a schematic side view showing a portion of the glass manufacturing apparatus of one embodiment.

Below, an embodiment of a glass manufacturing apparatus and a glass manufacturing method will be described with reference to the drawings. Note that in the drawings, for the sake of convenience, some of the components may be shown exaggerated or simplified. Furthermore, the dimensional ratios of each part may differ from the actual ones.

(Configuration of Glass Manufacturing Apparatus 11)
As shown in FIG. 1 , a glass manufacturing apparatus 11 includes a melting furnace 12 , a feeder 13 , a forming section 14 , an annealer 15 , a heat exchanger 16 , and a dryer 17 .

The melting furnace 12 is a box-shaped device having an inlet 12a and an outlet 12b, and is used to heat the glass raw material fed from the inlet 12a to melt the glass raw material and produce molten glass. The feeder 13 is a passage through which the molten glass flowing out from the outlet 12b of the melting furnace 12 flows to the forming section 14. The forming section 14 is a device that forms the molten glass that has passed through the feeder 13 into a desired shape. The annealer 15 is a device that removes distortion from the glass formed in the forming section 14.

The feeder 13 is provided with a flue 18. The flue 18 is a passage for gas that branches off from the feeder 13 and is provided to allow high-temperature gas to escape to the outside as exhaust heat.

As shown in FIG. 2, the flue 18 has an exhaust section 18a and a branch exhaust section 18b. The exhaust section 18a is provided so as to open to the outside at the upper end position of the flue 18. The branch exhaust section 18b is provided so as to branch off at the middle position of the flue 18 and open to the outside at the upper end. The branch exhaust section 18b also has an adjustment valve 18c that can adjust the amount of exhaust. The adjustment valve 18c is a lid that can adjust the size of the opening of the branch exhaust section 18b, and the adjustment valve 18c in this embodiment can be operated manually.

The heat exchanger 16 is disposed at the end position in the flue 18. The dryer 17 is connected to the heat exchanger 16 and is a device that produces metaboric acid from orthoboric acid using the thermal energy of the exhaust heat transferred through the heat exchanger 16.

More specifically, the heat exchanger 16 is made of a metal pipe and has a first end 16a, a second end 16b, and a coil-shaped main body 16c disposed therebetween. The main body 16c of the heat exchanger 16 is disposed within the flue 18, and the first end 16a is connected to the air pump AP outside the flue 18. The air pump AP is a device capable of supplying outside air from the first end 16a into the heat exchanger 16 and spraying it from the second end 16b. When the air pump AP is driven, the heat exchanger 16 sprays air that has been warmed by passing through the main body 16c in the flue 18 from the second end 16b.

The dryer 17 has a drying container 19, a stirring rod 20, and a motor 21. The drying container 19 has a cylindrical portion 19a, a first blocking portion 19b that blocks one end of the cylindrical portion 19a, and a second blocking portion 19c that blocks the other end of the cylindrical portion 19a. An inflow tube portion 19d that protrudes to the outside while communicating with the inside of the drying container 19 is provided at the top of the first blocking portion 19b. The second end portion 16b of the heat exchanger 16 is inserted into the inflow tube portion 19d. The inflow tube portion 19d is blocked except for the portion where the second end portion 16b is inserted. An outflow tube portion 19e that protrudes to the outside while communicating with the inside of the drying container 19 is provided at the top of the second blocking portion 19c. The outflow tube portion 19e is open to the outside. An openable inlet 19f is provided at the top of the cylindrical portion 19a. An openable outlet 19g is provided at the bottom of the first blocking portion 19b. The stirring rod 20 has a shaft portion 20a that extends along the axial center of the cylindrical portion 19a while being housed in the drying container 19, and a blade portion 20b that extends from the shaft portion 20a in a direction perpendicular to the axis. A plurality of blade portions 20b are provided in the longitudinal direction of the shaft portion 20a. Adjacent blade portions 20b in the longitudinal direction of the shaft portion 20a extend in different directions from the shaft portion 20a. The motor 21 is fixed to the outside of the second closing portion 19c and is connected to the shaft portion 20a of the stirring rod 20. The motor 21 is a device capable of rotating the stirring rod 20.

(Glass manufacturing method and its function)
The method for producing glass includes a "preparation step" of preparing glass raw materials, a "melting step" of melting the prepared glass raw materials to produce molten glass, and a "shaping step" of forming the molten glass into a desired shape.

In the preparation process, a boron source and the like are mixed in addition to the silicon source to prepare glass raw materials. In this embodiment, metaboric acid is used as the boron source. The silicon source in this preparation process is silica sand, and both the silica sand and metaboric acid are in a powder state. In the melting process, the prepared glass raw materials are fed into the melting furnace 12 from the inlet 12a, and the glass raw materials are heated in the melting furnace 12 to melt the glass raw materials and produce molten glass. The molten glass passes through the feeder 13 from the outlet 12b of the melting furnace 12 and reaches the forming section 14. In the forming process, the molten glass is formed into a desired shape in the forming section 14, and distortion of the formed glass is removed in the annealer 15.

Here, in the preparation process described above, metaboric acid is produced from orthoboric acid using exhaust heat from the glass manufacturing apparatus 11, and the produced metaboric acid is included in the glass raw material. In this embodiment, the glass manufacturing apparatus 11 that melts the glass raw material including metaboric acid to produce molten glass is the same as the glass manufacturing apparatus 11 that produces metaboric acid from orthoboric acid. In other words, in this embodiment, the exhaust heat used in the preparation process is the exhaust heat based on the melting process in the same manufacturing method by one glass manufacturing apparatus 11.

In more detail, in the preparation process, powdered orthoboric acid is first fed into the drying container 19 through the feed port 19f. Then, the exhaust heat from the glass manufacturing apparatus 11 is used to produce metaboric acid from the orthoboric acid. At this time, the exhaust heat from the glass manufacturing apparatus 11 is the exhaust heat from the flue 18 of the feeder 13. In more detail, a heat exchanger 16 is placed in the flue 18, and the thermal energy of the exhaust heat is transferred to the dryer 17 via the heat exchanger 16. More specifically, the air that has passed through the inside of the heat exchanger 16 is fed directly into the drying container 19 of the dryer 17 and passes through the drying container 19. At this time, the motor 21 is driven to rotate the stirring rod 20 to stir the orthoboric acid in the drying container 19.

At this time, the temperature around the heat exchanger 16 is adjusted by exhausting a portion of the exhaust heat from the branch exhaust section 18b of the flue 18. In this embodiment, the temperature around the heat exchanger 16 is adjusted by adjusting the size of the opening of the branch exhaust section 18b by operating the adjustment valve 18c, and adjusting the exhaust volume of the branch exhaust section 18b.

The metaboric acid produced in the preparation process is a monoclinic crystal. It is known that whether the metaboric acid produced is a monoclinic crystal, an orthorhombic crystal, or a cubic crystal depends on the temperature at which the orthoboric acid is heated. Therefore, in this embodiment, the air injected from the second end 16b of the heat exchanger 16 is set to 300°C, and the air flowing out from the outlet tube portion 19e is set to 200°C.

In this embodiment, the exhaust volume of the branch exhaust section 18b is adjusted so that the temperature around the heat exchanger 16 is 600°C, so that the air injected from the second end 16b is 300°C. Note that these temperatures vary depending on various conditions and are not limited to the above. In this embodiment, when 15 kilograms of orthoboric acid are put into the drying container 19 and the dryer 17 is driven for 8 hours while supplying 70 liters of air per minute from the air pump AP to the heat exchanger 16, the temperatures at which monoclinic metaboric acid is produced are the above temperatures.

In the preparation process, metaboric acid is generated in a state where the inside of the dryer 17 is coated with metaboric acid, specifically, the inner surface of the drying container 19 and the surface of the stirring rod 20 are coated with metaboric acid. Note that the drying container 19 and the stirring rod 20 in this embodiment are made of metal. Then, for example, a trial operation process for generating metaboric acid from orthoboric acid in a similar manner to the preparation process is performed once or multiple times in a state where the inside of the dryer 17 is not coated with metaboric acid, so that the inside of the dryer 17 is coated with metaboric acid. Furthermore, the metaboric acid generated in this trial operation process is discarded, for example, because there is a risk of it being contaminated with metal components that constitute the dryer 17.

As described above, glass is manufactured by carrying out the preparation step, the melting step, and the forming step.
Next, the effects of the above embodiment will be described below.
(1) Since metaboric acid is produced from orthoboric acid by utilizing exhaust heat from the glass manufacturing apparatus 11, metaboric acid can be obtained from orthoboric acid, which is easily available, without consuming any additional energy.

And because the glass raw materials contain metaboric acid produced in the preparation process, energy consumption in the subsequent melting process can be reduced compared to, for example, when the glass raw materials contain orthoboric acid instead of metaboric acid. In other words, the glass raw materials can be melted normally with less energy. Therefore, it is possible to reduce energy consumption while using orthoboric acid, which is easily available. Also, it is possible to suppress the generation of bubbles caused by the boron source at the initial stage of melting the raw materials in the melting process, and to avoid the problem of a significant decrease in the flow rate mentioned above.

In addition, since the boron source produced is metaboric acid, it is easier to handle than boric anhydride. In more detail, even if one were to try to produce boric anhydride from powdered orthoboric acid using the exhaust heat from the glass manufacturing apparatus 11, the boric anhydride would be in a molten state, and the powder would clump together into a single mass, making it difficult to handle when it is added to the glass raw material, but this can be avoided.

(2) The glass manufacturing apparatus 11 that melts glass raw materials including metaboric acid to produce molten glass is the same as the glass manufacturing apparatus 11 that produces metaboric acid from orthoboric acid. In other words, the exhaust heat used in the preparation process is the exhaust heat based on the melting process in the same manufacturing method. Therefore, for example, there is no need to use another glass manufacturing apparatus 11, and energy consumption in the melting process can be reduced.

(3) The exhaust heat used in the preparation process is the exhaust heat of the flue 18 of the feeder 13, so that the exhaust heat can be easily used. For example, by partially modifying the structure of the flue 18 originally provided in the glass manufacturing apparatus 11, the exhaust heat can be used without requiring major structural modifications. In addition, in this embodiment, the exhaust heat of the flue 18 of the feeder 13 is used, so that the exhaust heat can be used more easily than when the exhaust heat of the flue provided in the melting furnace 12, the forming unit 14, or the annealer 15 is used. For example, when the exhaust heat of the flue provided in the melting furnace 12 is used, the durability of the heat exchanger 16 may decrease and temperature control may become difficult due to the temperature becoming too high, but this can be avoided. Also, for example, when the exhaust heat of the flue provided in the forming unit 14 or the annealer 15 is used, the temperature may become low and temperature control may become difficult, but this can be avoided.

(4) A heat exchanger 16 is placed in the flue 18, and the thermal energy of the exhaust heat is transferred via the heat exchanger 16 to the dryer 17 that produces metaboric acid, so that the exhaust heat of the flue 18 can be used efficiently. In other words, the thermal energy of the exhaust heat can be used more efficiently than, for example, a configuration in which the exhaust gas passing through the flue 18 is directly directed at the dryer. In addition, for example, it is possible to avoid contamination of the produced metaboric acid by impurities contained in the exhaust gas.

(5) The air that has passed through the inside of the heat exchanger 16 is directly introduced into the drying container 19 of the dryer 17 and passed through the drying container 19, so that the moisture generated when metaboric acid is produced can be efficiently discharged to the outside of the drying container 19.

(6) A branch exhaust section 18b is provided upstream of the heat exchanger 16 in the flue 18, and a portion of the exhaust heat is exhausted from the branch exhaust section 18b to adjust the temperature around the heat exchanger 16. This makes it possible to prevent the temperature around the heat exchanger 16 from becoming excessively high, for example. Therefore, for example, the desired metaboric acid, which in this embodiment is monoclinic metaboric acid, can be produced satisfactorily.

(7) By adjusting the exhaust volume of the branch exhaust section 18b, the temperature around the heat exchanger 16 can be adjusted, for example, to an optimal temperature. Therefore, for example, the desired metaboric acid, which in this embodiment is monoclinic metaboric acid, can be more effectively produced.

(8) Since metaboric acid is generated while the inside of the dryer 17 is coated with metaboric acid, for example, the metal components that make up the dryer 17 are prevented from being mixed into the generated metaboric acid.

(9) The metaboric acid produced is monoclinic, so it is stable and easy to handle. In other words, if the metaboric acid is orthorhombic, it is prone to absorbing moisture and is unstable, and if the metaboric acid is cubic, it is prone to becoming sticky when produced and is difficult to handle, but these problems can be avoided.

This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.
In the above embodiment, the glass manufacturing apparatus 11 that melts the glass raw material including metaboric acid to produce molten glass and the glass manufacturing apparatus 11 that produces metaboric acid from orthoboric acid are the same, but they may be different glass manufacturing apparatuses. In other words, the exhaust heat used in the preparation step may be exhaust heat based on a melting step different from the melting step in the same manufacturing method.

In this way, for example, even in glass manufacturing equipment where it is difficult to utilize exhaust heat, metaboric acid can be used to reduce energy consumption in the melting process. For example, in a glass manufacturing equipment that melts glass raw materials containing halogens to produce molten glass, it is difficult to utilize exhaust heat because there is a risk of corrosion of the metal heat exchanger 16 of the above embodiment. Even in such glass manufacturing equipment where it is difficult to utilize exhaust heat, it is possible to reduce energy consumption in the melting process by using metaboric acid generated by utilizing the exhaust heat of another glass manufacturing equipment 11. In addition, the problem of a significant decrease in the flow rate described above can be avoided.

- In the above embodiment, the exhaust heat used in the preparation process is the exhaust heat from the flue 18 of the feeder 13, but this is not limited to this, and the exhaust heat from the flue provided in the melting furnace 12, the forming section 14, or the annealer 15 may be used. In addition, the exhaust heat used in the preparation process may be from a source other than the flue 18. For example, the exhaust heat may be used by contacting a dryer that produces metaboric acid with part of the housing that constitutes the glass manufacturing apparatus 11.

- In the above embodiment, a heat exchanger 16 is placed in the flue 18, and the thermal energy of the exhaust heat is transferred to the dryer 17 via the heat exchanger 16, but this is not limited to this. For example, the exhaust gas passing through the flue 18 may be directly directed at the dryer to utilize the exhaust heat.

- In the above embodiment, the air that has passed through the inside of the heat exchanger 16 is directly introduced into the drying container 19 of the dryer 17 and passed through the drying container 19, but this is not limited to this and may be changed to another configuration. For example, the heat exchanger 16 may be a heat exchanger of another configuration as long as it can transfer the thermal energy of the exhaust heat to the dryer 17.

- In the above embodiment, the temperature around the heat exchanger 16 is adjusted by exhausting a portion of the exhaust heat from the branch exhaust section 18b provided upstream of the heat exchanger 16 in the flue 18, but this is not limited to this, and the temperature may be adjusted using other structures or methods. For example, the temperature around the heat exchanger 16 may be adjusted by arranging a water-cooled cooling member upstream of the heat exchanger 16 in the flue 18.

- In the above embodiment, the temperature around the heat exchanger 16 is adjusted by adjusting the exhaust volume of the branch exhaust section 18b, but this is not limited to this. For example, the branch exhaust section 18b may not have an adjustment valve 18c and may exhaust a constant volume.

- In the above embodiment, metaboric acid is generated when the inside of the dryer 17 is coated with metaboric acid, but this is not limited thereto, and metaboric acid may be generated in an uncoated state.

In the above embodiment, the metaboric acid produced is a monoclinic crystal. However, the present invention is not limited to this. The metaboric acid produced may be an orthorhombic crystal or a cubic crystal.
In the above embodiment, the dryer 17 has the drying container 19, the stirring rod 20, and the motor 21, but may be changed to a dryer with another configuration. For example, the drying container may rotate without the stirring rod 20. Also, for example, a continuous dryer may be used in which heat is applied while the orthoboric acid is moved horizontally. Also, the drying container itself may be used as a storage container for storing the generated metaboric acid. In this case, for example, by filling the storage container with an inert gas such as nitrogen or creating a reduced pressure environment inside the storage container, it is possible to make it difficult for the metaboric acid to absorb moisture, and the metaboric acid can be stored stably. In this case, the dryer 17 can be connected and separated from the flue 18, and a large amount of metaboric acid can be stored by using multiple dryers.

- In the above embodiment, 15 kilograms of orthoboric acid is put into the drying container 19, and the dryer 17 is operated for 8 hours while 70 liters of air per minute is supplied from the air pump AP to the heat exchanger 16, but these numerical values may be changed. For example, 10 kilograms or 30 kilograms of orthoboric acid may be put in depending on the size of the drying container 19, etc. Also, for example, 50 liters or 100 liters of air per minute may be supplied from the air pump AP to the heat exchanger 16, which is made of a metal pipe, etc. Also, for example, the dryer 17 may be operated for 6 hours or 10 hours depending on the amount of orthoboric acid put in, etc.

11...glass manufacturing apparatus, 12...melting furnace, 12a...feeding port, 12b...outlet, 13...feeder, 14...molding section, 15...annealer, 16...heat exchanger, 16a...first end, 16b...second end, 16c...main body, 17...dryer, 18...flue, 18a...exhaust section, 18b...branched exhaust section, 18c...regulating valve, 19...drying vessel, 19a...cylindrical section, 19b...first blocking section, 19c...second blocking section, 19d...inlet tube section, 19e...outlet tube section, 19f...feeding port, 19g...removal port, 20...stirring rod, 20a...shaft section, 20b...blade section, 21...motor, AP...air pump.

Claims (13)

A method for producing glass, comprising: a preparation step of preparing a glass frit; and a melting step of melting the prepared glass frit to produce molten glass,
In the preparation step, metaboric acid is produced from orthoboric acid by utilizing exhaust heat from a glass manufacturing apparatus, and the metaboric acid is added to the glass raw material.
A method for manufacturing glass. The exhaust heat is generated by utilizing the exhaust heat based on the melting process.
A method for producing the glass according to claim 1 . The exhaust heat is exhaust heat from a melting process other than the melting process.
A method for producing the glass according to claim 1 . The exhaust heat is exhaust heat from any one of a melting furnace, a feeder, a forming unit, and an annealer in the glass manufacturing apparatus.
A method for producing the glass according to any one of claims 1 to 3. A heat exchanger is disposed in the flue, and thermal energy of the exhaust heat is transferred to a dryer for producing the metaboric acid through the heat exchanger.
A method for producing the glass according to claim 4. The air that has passed through the inside of the heat exchanger is directly introduced into a drying container of the dryer and passed through the drying container.
A method for producing the glass according to claim 5. A branch exhaust section is provided upstream of the heat exchanger in the flue, and a part of the exhaust heat is exhausted from the branch exhaust section to adjust the temperature around the heat exchanger.
A method for producing the glass according to claim 5. The temperature around the heat exchanger is adjusted by adjusting the exhaust amount of the branch exhaust section.
A method for producing the glass according to claim 7. The metaboric acid is generated in a state where the inside of the dryer is coated with the metaboric acid.
A method for producing the glass according to claim 5. The metaboric acid is monoclinic.
A method for producing the glass according to any one of claims 1 to 3. a melting furnace for melting glass raw materials to produce molten glass;
A flue for releasing exhaust heat to the outside,
A heat exchanger disposed in the flue;
A dryer connected to the heat exchanger and producing metaboric acid from orthoboric acid by the thermal energy of the exhaust heat transferred through the heat exchanger;
A glass manufacturing apparatus comprising: A branched exhaust section is provided upstream of the heat exchanger in the flue.
The glass manufacturing apparatus of claim 11. The branch exhaust section has an adjustment valve capable of adjusting the exhaust amount.
13. The glass manufacturing apparatus of claim 12.

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