WO2024111441A1 - Glass production method and glass production device - Google Patents

Abstract

The glass production method generates at least CO gas from CO₂ gas and H₂ gas by an overall reaction represented by formula (1) or formula (2) in the specification and forms a flame within a glass melting furnace by burning, by a burner, a combustion-supporting gas and a combustible gas containing the generated CO gas.

Description

Glass manufacturing method and glass manufacturing apparatus

This disclosure relates to a glass manufacturing method and a glass manufacturing apparatus.

The glass manufacturing apparatus includes a burner that forms a flame inside a glass melting furnace. The burner forms the flame by burning a combustible gas and a combustion supporting gas. The combustible gas is, for example, natural gas. The natural gas contains _CH4 gas as a main component. The combustion supporting gas is, for example, pure oxygen gas or air. The flame heats glass raw materials and molten glass obtained by melting the glass raw materials.

As mentioned above, air may be used as the combustion supporting gas. In this case, since the _N2 gas, which occupies most of the air, does not contribute to combustion, a large amount of air is used and a large amount of combustion gas is discharged from the glass melting furnace. Combustion gas refers to the gas remaining after the combustion reaction between the combustible gas and the combustion supporting gas (including _N2 gas that does not contribute to the combustion reaction). In order to recover the heat of the combustion gas discharged in large quantities, a first heat regenerator and a second heat regenerator may be provided next to the glass melting furnace.

The first and second heat storage chambers are used in combination with the first and second burners. The glass manufacturing apparatus alternately repeats the process of the first burner forming a flame inside the glass melting furnace and the second burner forming a flame inside the glass melting furnace.

The first heat storage chamber recovers heat from the combustion gas discharged from the glass melting furnace while the second burner forms a flame inside the glass melting furnace. The first heat storage chamber releases the heat previously recovered to heat at least one of the combustible gas and the combustion supporting gas while the first burner forms a flame inside the glass melting furnace. The first burner forms a flame inside the glass melting furnace by combusting the combustible gas and the combustion supporting gas, at least one of which has been heated in the first heat storage chamber.

Similarly, the second heat storage chamber recovers heat from the combustion gas discharged from the glass melting furnace while the first burner forms a flame inside the glass melting furnace. The second heat storage chamber releases the heat previously recovered to heat at least one of the combustible gas and the combustion supporting gas while the second burner forms a flame inside the glass melting furnace. The second burner forms a flame inside the glass melting furnace by combusting the combustible gas and the combustion supporting gas, at least one of which has been heated in the second heat storage chamber.

The first heat storage chamber of Patent Document 1 releases heat while the first burner forms a flame inside the glass melting furnace to promote an endothermic reaction. As an example of the endothermic reaction, a reaction is disclosed in which CO gas and H2 gas are generated from _CH4 gas, _H2O gas _, and _CO2 gas. The CO gas and _H2 gas generated in the first heat storage chamber are supplied to the first burner as combustible gas.

As mentioned above, pure oxygen gas may be used as the combustion supporting gas. In this case, the combustion supporting gas does not contain _N2 gas. Therefore, the amount of combustion gas discharged is small and a heat regenerator is not required, so that the design freedom of the glass melting furnace is increased. In addition, the _N2 gas that does not contribute to combustion is not heated unnecessarily, and the glass can be efficiently heated by the combustion heat. Furthermore, the generation of _NOx gas can be suppressed.

In place of a regenerator, a recuperator is sometimes used as a means of recovering heat from the combustion gases discharged from the glass melting furnace.

The recuperator of Patent Document 2 heats air by heat exchange with combustion gas. The air transports heat from the recuperator to a reactor. The reactor heats natural gas by heat exchange with the air heated by the recuperator, and promotes an endothermic reaction that produces _CH4 gas from _CmHn gas (m and n are integers of ₂ or more) contained in the natural gas.

Patent Document 3 discloses that if the H ₂ O gas concentration in the atmosphere inside a glass melting furnace is too high, the moisture concentration in the molten glass will be too high, resulting in poor glass quality (for example, defects will occur on the bottom surface of float glass).

Japanese Patent No. 3705713 Japanese Patent No. 6980795 Japanese Patent No. 6144622

Natural gas is generally used as a combustible gas burned in a burner. Natural gas contains _CH4 gas as a main component. When _CH4 gas is burned, _CO2 gas is generated. Therefore, in order to reduce the amount of _CO2 gas generated and thus the amount of _CO2 gas discharged, it is conceivable to use _H2 gas instead of _CH4 gas.

When _H2 gas is burned instead of _CH4 gas, _H2O gas is generated by the reaction between _H2 gas and _O2 gas, and _CO2 gas is not generated. However, the _H2O gas concentration in the furnace atmosphere increases because _CO2 gas is not generated. This is remarkable when pure oxygen gas is used as the combustion supporting gas. When pure oxygen gas is used, the _H2O gas concentration in the furnace atmosphere can theoretically be 100% by volume.

In addition, the glass frit may release gas when melted. For example, if the glass frit contains carbonate such as calcium carbonate or magnesium carbonate, the glass frit will release _CO2 gas when melted. Therefore, the _H2O gas concentration in the furnace atmosphere is actually less than 100% by volume.

If the _H2O gas concentration in the furnace atmosphere is too high, NaOH gas derived from Na contained in the molten glass is likely to be generated, and furnace materials such as bricks are likely to corrode. Alternatively, if the _H2O gas concentration in the furnace atmosphere is too high, the moisture concentration in the molten glass may be too high, resulting in a deterioration in the quality of the glass.

One aspect of the present disclosure provides a technique for reducing the H ₂ O gas concentration in the furnace atmosphere of a glass melting furnace when H ₂ gas is used as a combustible gas.

A glass manufacturing method according to one embodiment of the present disclosure includes generating at least CO gas from _CO2 gas and _H2 gas by an overall reaction represented by the following formula (1) or the following formula (2), and burning the generated flammable gas containing the CO gas and a combustion-supporting gas with a burner to form a flame inside a glass melting furnace.

According to one aspect of the present disclosure, when _H2 gas is used as a combustible gas, _H2 gas and _CO2 gas are converted to generate at least CO gas, and the generated combustible gas containing CO gas and combustion supporting gas are burned by a burner. This can reduce the _H2O gas concentration in the combustion gas and the _H2O gas concentration in the furnace atmosphere of a glass melting furnace.

FIG. 1 is a diagram showing a glass manufacturing apparatus according to an embodiment. FIG. 2 is a diagram showing an example of a reaction (x=0.5) in which the overall reaction is represented by formula (1). FIG. 3 is a diagram showing examples 1 to 14 of combinations of a combustible gas, a combustion supporting gas, an H ₂ O gas concentration in the combustion gas, and an H ₂ O gas concentration in the furnace atmosphere. FIG. 4 shows a first embodiment of a glass manufacturing apparatus including a recuperator and a reactor. FIG. 5 shows a second embodiment of a glass manufacturing apparatus including a recuperator and a reactor. FIG. 6 shows a third embodiment of a glass manufacturing apparatus including a recuperator and a reactor. FIG. 7 is a diagram showing a first embodiment of a glass manufacturing apparatus including a first heat accumulation chamber and a second heat accumulation chamber.

Below, an embodiment of the present disclosure will be described with reference to the drawings. Note that the same or corresponding configurations in each drawing will be given the same reference numerals, and descriptions may be omitted. In the specification, "~" indicating a numerical range means that the numerical values before and after it are included as the lower and upper limits.

With reference to FIG. 1, a glass manufacturing apparatus 1 according to one embodiment will be described. The glass manufacturing apparatus 1 includes a glass melting furnace 10. The glass melting furnace 10 contains glass raw materials and molten glass obtained by melting the glass raw materials. After being removed from the glass melting furnace 10, the molten glass is formed into a desired shape and slowly cooled. In this way, a glass product is obtained.

The glass raw material is prepared by mixing a plurality of types of materials. The glass raw material may contain a clarifier. The glass raw material may contain glass cullet in order to recycle the glass. The glass raw material may be a powder raw material or a granulated raw material obtained by granulating the powder raw material. The glass raw material is determined according to the composition of the glass product.

The glass melting furnace 10 is made of firebricks. Firebricks include, for example, zirconia-based electrocast bricks, alumina-based electrocast bricks, alumina-zirconia-based electrocast bricks, AZS (Al-Zr-Si)-based electrocast bricks, dense fired bricks, etc. The glass melting furnace 10 may be made of multiple types of firebricks.

The glass manufacturing apparatus 1 includes a burner 20. The burner 20 forms a flame inside the glass melting furnace 10. The flame heats the glass raw materials and the molten glass. The glass raw materials are added from above to the liquid surface of the molten glass, forming a layer on at least a portion of the liquid surface. The glass raw materials gradually melt into the molten glass. Although only one burner 20 is shown in FIG. 1, there are usually multiple burners 20.

The glass manufacturing apparatus 1 may also use multiple electrodes (not shown) as a heat source. The multiple electrodes apply an AC voltage to the molten glass, thereby electrically heating the molten glass. In this case, the molten glass generates heat. The glass manufacturing apparatus 1 may also use an electric heater (not shown) as a heat source. The electric heater generates heat by itself. It is sufficient that the glass manufacturing apparatus 1 is equipped with at least a burner 20 as a heat source.

The burner 20 forms a flame by burning a combustible gas and a combustion-supporting gas. In this embodiment, _H2 gas (more specifically, a gas obtained by transforming _H2 gas as described later) is used as at least a part of the combustible gas. By using _H2 gas, the amount of _CO2 gas generated and therefore the amount of _CO2 gas emitted can be reduced compared to the case of using _CH4 gas.

In addition, _H2 gas may be used as at least a part of the combustible gas, and natural gas may be used in combination. Since natural gas contains _CH4 gas as a main component, the less natural gas used, the better. From the viewpoint of reducing the amount of _CO2 gas generated, the amount of natural gas used is preferably 0% by volume to 50% by volume, more preferably 0% by volume to 25% by volume, and even more preferably 0% by volume.

When _H2 gas is burned instead of _CH4 gas, _H2O gas is generated by the reaction between _H2 gas and _O2 gas, and _CO2 gas is not generated. However, the _H2O gas concentration in the furnace atmosphere increases because _CO2 gas is not generated. This is remarkable when pure oxygen gas is used as the combustion supporting gas. When pure oxygen gas is used, the _H2O gas concentration in the furnace atmosphere can theoretically be 100% by volume.

In addition, the glass frit may release gas when melted. For example, if the glass frit contains carbonate such as calcium carbonate or magnesium carbonate, the glass frit will release _CO2 gas when melted. Therefore, the _H2O gas concentration in the furnace atmosphere is actually less than 100% by volume.

If the _H2O gas concentration in the furnace atmosphere is too high, NaOH gas derived from Na contained in the molten glass is likely to be generated, and furnace materials such as bricks are likely to corrode. Alternatively, if the _H2O gas concentration in the furnace atmosphere is too high, the moisture concentration in the molten glass is too high, which may result in a deterioration in the quality of the glass.

If air is used as the combustion supporting gas instead of pure oxygen gas, the _H2O gas concentration in the furnace atmosphere can be reduced. In this case, since _N2 gas, which occupies most of the air, does not contribute to combustion, a large amount of air is used and a large amount of combustion gas is discharged from the glass melting furnace. Combustion gas refers to the gas (including _N2 gas that does not contribute to combustion) remaining after the combustion reaction between combustible gas and combustion supporting gas. In order to recover the heat of the combustion gas discharged in large amounts, a heat regenerator is provided next to the glass melting furnace 10.

On the other hand, if pure oxygen gas is used as the combustion supporting gas, the combustion supporting gas does not contain _N2 gas. Therefore, the amount of combustion gas discharged is small and a heat regenerator is not required, so that the degree of freedom in designing the glass melting furnace 10 is increased. In addition, the _N2 gas that does not contribute to combustion is not heated unnecessarily, and the glass can be efficiently heated by the combustion heat. Furthermore, the generation of _NOx gas can be suppressed.

However, if pure oxygen gas is used as the combustion supporting gas, the _H2O gas concentration in the furnace atmosphere will be higher than when air is used. If oxygen-enriched air is used as the combustion supporting gas instead of pure oxygen gas, the _H2O gas concentration will also be higher than when air is used. Oxygen-enriched air is a mixed gas of pure oxygen gas and air, and has a higher oxygen gas concentration than air.

The glass manufacturing apparatus 1 of the present embodiment includes a gas transformation unit 30 that transforms _H2 gas in order to reduce the _H2O gas concentration in the furnace atmosphere. One or more gas transformation units 30 (one in FIG. 1) are provided. The gas transformation unit 30 generates at least CO gas and H2O gas from _CO2 gas and _H2 gas by a general reaction represented by the following formula (1) or (2). _CO2 gas and _H2 gas are reactants, and CO gas and _H2O gas are products. The products may further include _H2 gas or _{CO2 gas} .

　式（１）及び式（２）において、ｘは、ガス変成部３０に対して供給される、Ｈ_２ガスに対するＣＯ_２ガスのモル比を表す。モル比ｘは０．００よりも大きい。一般的に、モル比は体積比と一致する。

In formulas (1) and (2), x represents the molar ratio of _CO2 gas to _H2 gas supplied to the gas shifter 30. The molar ratio x is greater than 0.00. In general, the molar ratio corresponds to the volume ratio.

The gas shifting unit 30 may simultaneously proceed with a reaction whose overall reaction is represented by formula (1) or formula (2). Therefore, the gas shifting unit 30 may be supplied with _CO2 gas and _H2 gas as reactants, and may be supplied with other gases.

FIG. 2 shows an example of a reaction (x=0.5) in which the overall reaction is represented by formula (1). In FIG. 2, ΔH is the amount of change in enthalpy (kJ/mol). Enthalpy is also called heat content. As is clear from FIG. 2, the reaction in which the overall reaction is represented by formula (1) or formula (2) is an endothermic reaction. The product of the endothermic reaction (CO gas) potentially contains a larger amount of heat than the reactant of the endothermic reaction ( _H2 gas).

The overall reaction represented by formula (1) or formula (2) includes, for example, at least one of the following: (A) a reverse water gas shift (RWGS) reaction; (B) a combination of a methanation reaction and a dry reforming (DRM) reaction; and (C) a combination of a methanation reaction and a steam reforming (STR) reaction.

Compared to (B) and (C), (A) can reduce the number of reactions used and simplify the device configuration. On the other hand, (B) and (C) can lower the reaction temperature compared to (A). Incidentally, the reverse shift reaction is represented by the following formula (3). The methanation reaction is represented by the following formula (4). The DRM reaction is represented by the following formula (5). Furthermore, the STR reaction is represented by the following formula (6).

　式（３）から、逆シフト反応が吸熱反応であることが分かる。式（４）から、メタネーション反応が発熱反応であることが分かる。式（５）から、ＤＲＭ反応が吸熱反応であることが分かる。式（６）から、ＳＴＲ反応が吸熱反応であることが分かる。吸熱反応の生成物（ＣＯガス）は、吸熱反応の反応物（Ｈ_２ガス又はＣＨ_４ガス）よりも大きな熱量を潜在的に含んでいる。それゆえ、吸熱反応の生成物（ＣＯガス）を燃焼すれば、吸熱反応の反応物（Ｈ_２ガス又はＣＨ_４ガス）を燃焼するよりも、大きな燃焼熱を得ることができる。

From equation (3), it can be seen that the reverse shift reaction is an endothermic reaction. From equation (4), it can be seen that the methanation reaction is an exothermic reaction. From equation (5), it can be seen that the DRM reaction is an endothermic reaction. From equation (6), it can be seen that the STR reaction is an endothermic reaction. The endothermic reaction product (CO gas) potentially contains a larger amount of heat than the endothermic reaction reactant ( _H2 gas or _CH4 gas). Therefore, by burning the endothermic reaction product (CO gas), it is possible to obtain a larger combustion heat than by burning the endothermic reaction reactant ( _H2 gas or _CH4 gas).

The gas transformation unit 30 supplies products such as CO gas to the burner 20. The gas supplied includes, for example, CO gas and _H2O gas (see formula (1) and formula (2)). The gas supplied may further include _H2 gas (see formula (1)) or _CO2 gas (see formula (2)). The gas supplied may include both _H2 gas and _CO2 gas.

The burner 20 combusts the flammable gas containing the CO gas generated in the gas shifting section 30 and the combustion supporting gas to form a flame inside the glass melting furnace 10. By burning the CO gas, the combustion heat per mole can be improved compared to burning the _H2 gas.

The combustion reaction of CO gas is expressed by the following formula (7), and the combustion reaction of _H2 gas is expressed by the following formula (8). Here, the lower heating value is used as the combustion heat of _H2 gas.

　式（７）と式（８）から、ＣＯガスを燃焼することで、Ｈ_２ガスを燃焼するよりも、１モル当たりの燃焼熱を向上できることが分かる。

From equations (7) and (8), it can be seen that by burning CO gas, the heat of combustion per mole can be improved compared to burning _H2 gas.

The combustion reaction of the combustible gas and the combustion supporting gas by the burner 20 is expressed, for example, by the following formula (9) or the following formula (10).

　式（９）は、式（１）で得られた生成物の燃焼反応を表す。一方、式（１０）は、式（２）で得られた生成物の燃焼反応を表す。式（９）及び式（１０）において、ｘは、ガス変成部３０に対して供給される、Ｈ_２ガスに対するＣＯ_２ガスのモル比を表す。モル比ｘは０．００よりも大きい。

Equation (9) represents the combustion reaction of the product obtained by equation (1). Meanwhile, equation (10) represents the combustion reaction of the product obtained by equation (2). In equations (9) and (10), x represents the molar ratio of _CO2 gas to _H2 gas supplied to the gas shift converter 30. The molar ratio x is greater than 0.00.

The combustion reaction between the combustible gas and the combustion-supporting gas needs to include at least the combustion reactions represented by formulas (9) and (10), and may further include other combustion reactions.

As described above, the burner 20 burns the combustible gas containing CO gas generated in the gas shifter 30 and the combustion supporting gas. Therefore, the combustion gas contains not only _H2O gas but also _CO2 gas. This is also clear from formulas (9) and (10). _{The H2O} gas can be diluted with the CO2 gas, and the _H2O gas concentration in the furnace atmosphere can be reduced.

3 shows examples 1 to 14 of combinations of combustible gas, combustion supporting gas, _H2O gas concentration in combustion gas, and _H2O gas concentration in furnace atmosphere. The furnace atmosphere includes the gas released by the glass frit when melting the glass frit in addition to the combustion gas. Therefore, the _H2O gas concentration in the furnace atmosphere is lower than the _H2O gas concentration in the combustion gas.

As shown in Fig. 3, when _H2 gas is used as the combustible gas instead of _CH4 gas, _CO2 gas is not generated, and the _H2O gas concentration in the furnace atmosphere is increased. This is remarkable when pure oxygen gas is used as the combustion supporting gas. When pure oxygen gas is used, the _H2O gas concentration in the combustion gas is 100 volume %, and the _H2O gas concentration in the furnace atmosphere is 88 volume %.

The _H2O gas concentration in the furnace atmosphere depends on the type of glass raw material, but is mainly determined by the types of combustible gas and combustion supporting gas. Therefore, in this embodiment, the _H2O gas concentration in the combustion gas is adopted as a parameter to be controlled.

The _H2O gas concentration in the combustion gas is preferably 67% by volume or less. Conventionally, molten glass has been produced by burning _CH4 gas and _O2 gas (pure oxygen gas), and it has been confirmed that if the _H2O gas concentration in the combustion gas is 67% by volume or less, there is no problem with the quality of glass products or corrosion of furnace materials.

The molar ratio x is preferably 0.50 or more so that the _H2O gas concentration in the combustion gas is 67 volume % or less (see FIG. 3). The _H2O gas concentration in the combustion gas is more preferably 65 volume % or less. The molar ratio x is more preferably 0.55 or more so that the _H2O gas concentration in the combustion gas is 65 volume % or less (see FIG. 3).

The lower limit of the _H2O gas concentration in the combustion gas is not particularly limited, but from the viewpoint of feasibility, it is preferable that it is 20% by volume or more. In order to make the _H2O gas concentration in the combustion gas 20% by volume or more, it is preferable that the molar ratio x is 4.00 or less (see FIG. 3).

It is more preferable that the molar ratio x is 1.00 or less. If the molar ratio x is 1.00 or less, the combustion reaction is expressed by formula (9). On the other hand, if the molar ratio x exceeds 1.00, the combustion reaction is expressed by formula (10). As is clear from formula (10), if the molar ratio x exceeds 1.00, there is (x-1) moles of _CO2 gas that does not contribute to combustion. This _CO2 gas not only does not generate combustion heat, but also consumes combustion heat in vain. If the molar ratio x is 1.00 or less, there is no need to heat the (x-1) moles of _CO2 gas that does not contribute to combustion in vain, and the glass can be efficiently heated by the combustion heat.

A dedicated supply source such as a gas cylinder (not shown) may be used to supply _CO2 gas to the gas shift converter 30, but in this embodiment, a circulation line 50 is used. The circulation line 50 supplies at least a portion of the _CO2 gas contained in the combustion gas from the glass melting furnace 10 to the gas shift converter 30. At least a portion of the _CO2 gas discharged from the glass melting furnace 10 can be used as a reactant for the overall reaction. _{The CO2} gas can be circulated, and the amount of _CO2 gas discharged can be reduced.

A dehydration tank 51 is preferably provided in the middle of the circulation line 50. The dehydration tank 51 separates H ₂ O gas and CO ₂ gas by removing H ₂ O gas from the combustion gas. At least a part of the separated CO ₂ gas can be used as a reactant for the overall reaction. The supply of H ₂ O gas to the gas shifter 30 can be restricted, and the H ₂ O gas concentration in the furnace atmosphere of the glass melting furnace 10 can be reduced. The dehydration tank 51 only needs to remove at least a part of the H ₂ O gas, but in this embodiment, it removes substantially all of the H ₂ O gas.

The glass manufacturing apparatus 1 preferably recovers heat from the combustion gas burned by the burner 20 and uses the recovered heat to advance the overall reaction represented by formula (1) or formula (2). By recovering heat from the burned combustion gas, energy waste can be reduced. As a means for recovering heat, a recuperator or a heat storage chamber, which will be described later, is used. The heat recovery means and the like will be described below.

With reference to FIG. 4, a first embodiment of a glass manufacturing apparatus 1 including a recuperator 60 and a reactor 70 will be described. The glass manufacturing apparatus 1 includes a glass melting furnace 10, a burner 20, a recuperator 60, and a reactor 70. The reactor 70 is an example of a gas transformation section 30, and for example, advances a reverse shift reaction. Below, differences from the glass manufacturing apparatus 1 shown in FIG. 1 will be mainly described.

The recuperator 60 heats the heat medium by heat exchange with the combustion gas discharged from the glass melting furnace 10. The heat medium may be gas or liquid, but since the temperature of the combustion gas is high, it is preferable that the heat medium is gas in order to prevent boiling. The heat medium is preferably air. The recuperator 60 transfers heat between the combustion gas and the heat medium (e.g., air) without mixing them. The recuperator 60 is provided outside the glass melting furnace 10 in FIG. 4, but may be provided inside the glass melting furnace 10. One or more recuperators 60 (one in FIG. 4) are provided. The recuperator 60 is thermally connected to the reactor 70 via a heat transport line 80. The heat transport line 80 transports the heat medium from the recuperator 60 to the reactor 70.

The reactor 70 heats the _CO2 gas and _H2 gas by heat exchange with the heat medium heated by the recuperator 60 to promote the reverse shift reaction, and generates at least CO gas from the CO2 gas and _H2 gas. _{The CO2} gas and _H2 gas are reactants, and the CO gas and _H2O gas are products (see formula (3)). The products may further include _H2 gas or _CO2 gas (see formulas (1) and (2)). The reactor 70 transfers heat between the reactants and products of the reverse shift reaction without mixing them with a heat medium (e.g., air).

Since the reverse shift reaction is an endothermic reaction, heat can be efficiently recovered from the heat medium, and the heat recovered from the combustion gas can be efficiently used. In addition, the product of the endothermic reaction (CO gas) potentially contains a larger amount of heat than the reactant of the endothermic reaction ( _H2 gas). Therefore, by burning CO gas, the combustion heat per mole can be improved compared to burning _H2 gas (see formulas (7) and (8)). As a result, the energy consumption rate of molten glass can be reduced. The energy consumption rate is the amount of energy consumed from outside the system to produce one ton of molten glass.

The reactions occurring in the reactor 70 may be endothermic reactions overall, and may include reactions other than the reverse shift reaction. Therefore, the reactants and products in the reactor 70 are not particularly limited. The products (i.e., combustible gas) generated in the reactor 70 are supplied to the burner 20 via the first supply line 21. On the other hand, the combustion supporting gas is supplied to the burner 20 via the second supply line 22.

The glass manufacturing apparatus 1 preferably includes a circulation line 50. The circulation line 50 supplies at least a part of the _CO2 gas contained in the combustion gas burned by the burner 20 from the glass melting furnace 10 to the reactor 70. At least a part of the _CO2 gas discharged from the glass melting furnace 10 can be used as a reactant for the reverse shift reaction. _{The CO2} gas can be circulated, and the amount of _CO2 gas discharged can be reduced.

More preferably, the glass manufacturing apparatus 1 includes a dehydration tank 51 in the circulation line 50. The dehydration tank 51 separates H ₂ O gas and CO ₂ gas by removing H ₂ O gas from the combustion gas. The circulation of H _{2 O gas can be restricted while allowing the circulation of CO 2 gas. H 2 O gas} not only does not generate combustion heat, but also consumes the combustion heat in vain. If the circulation of H ₂ O gas can be restricted, the H ₂ O gas that does not contribute to combustion is not heated in vain, and the glass can be efficiently heated by the combustion heat. In addition, if the circulation of H ₂ O gas can be restricted, the H ₂ O gas concentration in the furnace atmosphere can be reduced. The dehydration tank 51, for example, removes substantially all H ₂ O gas from the combustion gas.

It is more preferable to provide a desulfurization tank 52 in the circulation line 50. The desulfurization tank 52 removes sulfur-containing gas from the combustion gas. The sulfur contained in the sulfur-containing gas originates from the glass raw materials, for example, from the fining agent. By providing the desulfurization tank 52 in the circulation line 50, the supply of sulfur-containing gas to the reactor 70 can be restricted. This allows the reactor 70 to be maintained in a clean state.

Unlike the heat storage chamber described below, the recuperator 60 and reactor 70 use a heat medium to recover heat from the combustion gas, so they can restrict the combustion gas from flowing directly into the reactor 70, and can keep the reactor 70 clean. Therefore, if the reactor 70 contains a metal catalyst, deterioration of the metal catalyst can be suppressed.

The reactor 70 may have a metal catalyst. The metal catalyst promotes the reverse shift reaction. The metal catalyst increases the reaction rate of the reverse shift reaction, allowing the reaction to reach equilibrium in a short time. By increasing the reaction rate of the reverse shift reaction, the metal catalyst can also reduce the volume of the reactor 70. As the metal catalyst, copper (Cu) or nickel (Ni) is used. Note that if the reaction rate is sufficiently fast, the metal catalyst may not be necessary.

With reference to FIG. 5, a second embodiment of the glass manufacturing apparatus 1 including a recuperator 60 and a reactor 70 will be described. Below, differences from the glass manufacturing apparatus 1 shown in FIG. 4 will be mainly described. As shown in FIG. 5, the glass manufacturing apparatus 1 preferably includes a heat exchanger 23.

The heat exchanger 23 is provided midway along the second supply line 22, and preheats the combustion-supporting gas (e.g., pure oxygen gas) by heat exchange with the heat medium heated in the recuperator 60. This allows for effective use of the heat recovered from the combustion gas, and reduces the energy consumption rate of the molten glass. The heat exchanger 23 transfers heat between the combustion-supporting gas and the heat medium (e.g., air) without mixing them.

The heat transport line 80 transports the heat transfer medium from the recuperator 60 to the heat exchanger 23. Preferably, the heat transport line 80 transports the heat transfer medium from the recuperator 60 to the reactor 70, and then transports the heat transfer medium from the reactor 70 to the heat exchanger 23. The reactants of the reverse shift reaction can be heated before the combustion-supporting gas is heated, making it easier to secure the heat required to advance the reverse shift reaction.

With reference to FIG. 6, a third embodiment of the glass manufacturing apparatus 1 including a recuperator 60 and a reactor 70 will be described. Below, differences from the glass manufacturing apparatus 1 shown in FIG. 4 will be mainly described. As shown in FIG. 6, the glass manufacturing apparatus 1 preferably includes a second heat exchanger 24 and a second dehydration tank 25.

The second heat exchanger 24 transfers heat from the product of the reactor 70 to the combustion supporting gas at a first point where the first supply line 21 overlaps with the second supply line 22. The second heat exchanger 24 transfers heat between the product of the reactor 70 and the combustion supporting gas without mixing them. The second dehydration tank 25 removes H ₂ O gas from the product of the reactor 70 at a second point downstream of the first point of the first supply line 21. The second dehydration tank 25 only needs to remove at least a portion of the H ₂ O gas, but in this embodiment, it removes substantially all of the H ₂ O gas.

The second dehydration tank 25 removes H ₂ O gas from the product of the reactor 70, for example, by cooling the product of the reactor 70. H ₂ O gas not only does not generate combustion heat, but also wastes the combustion heat. The second dehydration tank 25 limits the supply of H ₂ O gas to the burner 20. This avoids wasteful heating of H ₂ O gas that does not contribute to combustion, and allows the glass to be efficiently heated by the combustion heat. In addition, the H ₂ O gas concentration in the furnace atmosphere can be reduced.

Before the second dehydration tank 25 cools the product of the reactor 70, the second heat exchanger 24 transfers heat from the product of the reactor 70 to the combustion-supporting gas. This allows the heat recovered from the combustion gas to be used efficiently, reducing the energy consumption of the molten glass.

With reference to FIG. 7, a first embodiment of a glass manufacturing apparatus 1 including a first heat storage chamber 90A and a second heat storage chamber 90B will be described. The glass manufacturing apparatus 1 includes a glass melting furnace 10, a first burner 20A, a second burner 20B, a first heat storage chamber 90A, and a second heat storage chamber 90B. The first heat storage chamber 90A and the second heat storage chamber 90B are an example of a gas transformation section 30, and promote, for example, a reverse shift reaction. Below, differences from the glass manufacturing apparatus 1 shown in FIG. 1 will be mainly described.

The first heat storage chamber 90A and the second heat storage chamber 90B are used in combination with the first burner 20A and the second burner 20B. Note that while there is one first heat storage chamber 90A in FIG. 7, there may be more than one. Similarly, the number of second heat storage chambers 90B, the number of first burners 20A, and the number of second burners 20B may be one or more.

The glass manufacturing apparatus 1 alternately repeats the process of the first burner 20A forming a flame inside the glass melting furnace 10 and the second burner 20B forming a flame inside the glass melting furnace 10. Figure 7 shows the state in which the first burner 20A forms a flame inside the glass melting furnace 10.

The first heat regenerator 90A recovers heat from the combustion gas discharged from the glass melting furnace 10 while the second burner 20B forms a flame inside the glass melting furnace 10. The first heat regenerator 90A releases the previously recovered heat to promote a reverse shift reaction that generates at least CO gas from _CO2 gas and _H2 gas while the first burner 20A forms a flame inside the glass melting furnace 10. The first burner 20A forms a flame inside the glass melting furnace 10 by combusting the combustible gas containing CO gas and the combustion supporting gas generated in the first heat regenerator 90A.

Similarly, the second heat regenerator 90B recovers heat from the combustion gas discharged from the glass melting furnace 10 while the first burner 20A forms a flame inside the glass melting furnace 10. The second heat regenerator 90B releases the previously recovered heat to promote a reverse shift reaction that produces at least CO gas from _CO2 gas and _H2 gas while the second burner 20B forms a flame inside the glass melting furnace 10. The second burner 20B forms a flame inside the glass melting furnace 10 by combusting the combustible gas containing CO gas and the combustion supporting gas produced in the second heat regenerator 90B.

Unlike the recuperator 60 and reactor 70, the combustion gas flows directly into the first heat storage chamber 90A and the second heat storage chamber 90B. The heat of the combustion gas is stored in the hearths of the first heat storage chamber 90A and the second heat storage chamber 90B.

The first heat storage chamber 90A and the second heat storage chamber 90B heat the _CO2 gas and the _H2 gas to promote a reverse shift reaction, and generate at least CO gas from the _CO2 gas and the _H2 gas. The _CO2 gas and the _H2 gas are reactants, and the CO gas and the _H2O gas are products (see formula (3)). The products may further include _H2 gas or _CO2 gas (see formula (1) and formula (2)).

Since the reverse shift reaction is an endothermic reaction, it is possible to efficiently recover heat from the combustion gas and efficiently utilize the heat of the combustion gas. In addition, the product of the endothermic reaction (CO gas) potentially contains a larger amount of heat than the reactant of the endothermic reaction ( _H2 gas). Therefore, by burning CO gas, the combustion heat per mole can be improved compared to burning _H2 gas (see formulas (7) and (8)). As a result, the energy consumption rate of molten glass can be reduced.

The reactions occurring in the first heat storage chamber 90A and the second heat storage chamber 90B may be endothermic reactions overall, and may include reactions other than the reverse shift reaction. Therefore, there are no particular limitations on the reactants and products in the first heat storage chamber 90A and the second heat storage chamber 90B.

The glass manufacturing apparatus 1 preferably includes a circulation line 50. The circulation line 50 supplies at least a part of the _CO2 gas contained in the combustion gas discharged from the glass melting furnace 10 from the second heat storage chamber 90B to the first heat storage chamber 90A while the first burner 20A forms a flame inside the glass melting furnace 10. At least a part of the _CO2 gas discharged from the glass melting furnace 10 can be used as a reactant for the reverse shift reaction. The _CO2 gas can be circulated, and the amount of _CO2 gas discharged can be reduced.

The circulation line 50 may supply at least a part of the _CO2 gas contained in the combustion gas discharged from the glass melting furnace 10 from the first heat regenerator 90A to the second heat regenerator 90B while the second burner 20B forms a flame inside the glass melting furnace 10. Note that the circulation line 50 for circulating the _CO2 gas while the first burner 20A forms a flame inside the glass melting furnace 10 and the circulation line 50 for circulating the _CO2 gas while the second burner 20B forms a flame inside the glass melting furnace 10 are the same in this embodiment, but may be different or may be provided separately.

More preferably, the glass manufacturing apparatus 1 includes a dehydration tank 51 in the middle of the circulation line 50. The dehydration tank 51 separates H ₂ O gas and CO ₂ gas by removing H ₂ O gas from the combustion gas. The circulation of H ₂ O gas can be restricted while allowing the circulation of CO ₂ gas. H ₂ O gas not only does not generate combustion heat, but also consumes the combustion heat in vain. If the circulation of H ₂ O gas can be restricted, the H ₂ O gas that does not contribute to combustion is not heated in vain, and the glass can be efficiently heated by the combustion heat. In addition, if the circulation of H ₂ O gas can be restricted, the H ₂ O gas concentration in the furnace atmosphere can be reduced. Although the dehydration tank 51 only needs to remove at least a part of the H ₂ O gas, in this embodiment, substantially all of the H ₂ O gas is removed.

It is more preferable to provide a desulfurization tank 52 in the circulation line 50. The desulfurization tank 52 removes sulfur-containing gas from the combustion gas. The sulfur contained in the sulfur-containing gas originates from the glass raw materials, for example, from the fining agent. By providing the desulfurization tank 52 in the circulation line 50, the supply of sulfur-containing gas to the first heat storage chamber 90A or the second heat storage chamber 90B can be restricted.

The following supplementary notes are disclosed regarding the above-described embodiments.
[Appendix 1]
Producing at least CO gas from CO ₂ gas and H ₂ gas by a reaction represented by the overall reaction formula (1) or formula (2) described in the specification;
The generated flammable gas containing CO gas and the combustion supporting gas are combusted by a burner to form a flame inside the glass melting furnace;
The method for producing glass comprising the steps of:
[Appendix 2]
The glass manufacturing method according to claim 1, wherein a H ₂ O gas concentration in the combustion gas combusted in the burner is 67 volume % or less.
[Appendix 3]
The glass manufacturing method according to claim 1 or 2, wherein at least a portion of the _CO2 gas contained in the combustion gas burned by the burner is used as a reactant for the overall reaction.
[Appendix 4]
H ₂ O gas is removed from the combustion gas burned by the burner to separate H ₂ O gas and CO ₂ gas;
4. The method of claim 3, wherein at least a portion of the separated _CO2 gas is used as a reactant in the overall reaction.
[Appendix 5]
The method for producing glass according to any one of claims 1 to 4, wherein in the overall reaction, a molar ratio x of _CO2 gas to _H2 gas is greater than 0.00 and less than or equal to 1.00.
[Appendix 6]
The method for producing a glass according to any one of Appendices 1 to 5, wherein the overall reaction represented by formula (1) or formula (2) includes at least one of (A) a reverse shift reaction, (B) a combination of a methanation reaction and a dry reforming reaction, and (C) a combination of a methanation reaction and a steam reforming reaction.
[Appendix 7]
The method for producing glass according to any one of Appendices 1 to 6, wherein heat recovered from a combustion gas combusted in the burner is used for the overall reaction represented by the formula (1) or the formula (2).
[Appendix 8]
A gas conversion unit that generates at least CO gas from _CO2 gas and _H2 gas by an overall reaction represented by formula (1) or formula (2) described in the specification;
a burner that forms a flame inside the glass melting furnace by combusting the flammable gas containing the CO gas generated in the gas shifting unit and a combustion supporting gas;
A glass manufacturing apparatus comprising:
[Appendix 9]
The glass manufacturing apparatus according to claim 8, wherein a H ₂ O gas concentration in the combustion gas combusted by the burner is 67 volume % or less.
[Appendix 10]
The glass manufacturing apparatus according to claim 8 or 9, further comprising a circulation line for supplying at least a portion of the _CO2 gas contained in the combustion gas burned by the burner from the glass melting furnace to the gas transformer.
[Appendix 11]
The glass manufacturing apparatus according to claim 10, further comprising a dehydration tank disposed in the circulation line for removing H ₂ O gas from the combustion gas.
[Appendix 12]
The glass manufacturing apparatus according to any one of claims 8 to 11, wherein the molar ratio x of _CO2 gas to _H2 gas in the overall reaction is greater than 0.00 and less than or equal to 1.00.
[Appendix 13]
The overall reaction represented by the formula (1) or the formula (2) includes at least one of (A) a reverse shift reaction, (B) a combination of a methanation reaction and a dry reforming reaction, and (C) a combination of a methanation reaction and a steam reforming reaction.
[Appendix 14]
The glass manufacturing apparatus according to any one of Appendices 8 to 13, wherein heat recovered from a combustion gas combusted in the burner is used for the overall reaction represented by the formula (1) or the formula (2).

The above describes the glass manufacturing method and glass manufacturing apparatus according to the present disclosure, but the present disclosure is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. Naturally, these also fall within the technical scope of the present disclosure.

This application claims priority based on Patent Application No. 2022-188268, filed with the Japan Patent Office on November 25, 2022, and the entire contents of Patent Application No. 2022-188268 are incorporated herein by reference.

Reference Signs List 1 Glass manufacturing apparatus 10 Glass melting furnace 20 Burner 30 Gas transformer

Claims (14)

The overall reaction is represented by the following formula (1) or the following formula (2), and at least CO gas is produced from _CO2 gas and _H2 gas;
The generated flammable gas containing CO gas and the combustion supporting gas are combusted by a burner to form a flame inside the glass melting furnace;
The method for producing glass comprising the steps of:

The glass manufacturing method according to claim 1 , wherein the H ₂ O gas concentration in the combustion gas combusted in the burner is 67% by volume or less. The glass manufacturing method according to claim 1 or 2, wherein at least a portion of _CO2 gas contained in the combustion gas burned in the burner is used as a reactant in the overall reaction. H ₂ O gas is removed from the combustion gas burned by the burner to separate H ₂ O gas and CO ₂ gas;
4. The method of claim 3, wherein at least a portion of the separated _CO2 gas is used as a reactant in the overall reaction. 3. The method for producing glass according to claim 1 or 2, wherein the molar ratio x of _CO2 gas to _H2 gas in the overall reaction is greater than 0.00 and less than or equal to 1.00. The method for producing glass according to claim 1 or 2, wherein the overall reaction represented by formula (1) or formula (2) includes at least one of (A) a reverse shift reaction, (B) a combination of a methanation reaction and a dry reforming reaction, and (C) a combination of a methanation reaction and a steam reforming reaction. The glass manufacturing method according to claim 1 or 2, wherein the overall reaction represented by formula (1) or formula (2) uses heat recovered from the combustion gas burned by the burner. A gas conversion unit that generates at least CO gas from _CO2 gas and _H2 gas by an overall reaction represented by the following formula (1) or the following formula (2);
a burner that forms a flame inside the glass melting furnace by combusting the flammable gas containing the CO gas generated in the gas shifting unit and a combustion supporting gas;
A glass manufacturing apparatus comprising:

The glass manufacturing apparatus according to claim 8 , wherein a H ₂ O gas concentration in the combustion gas combusted by the burner is 67% by volume or less. The glass manufacturing apparatus according to claim 8 or 9, further comprising a circulation line for supplying at least a portion of CO ₂ gas contained in the combustion gas combusted by the burner from the glass melting furnace to the gas transformer unit. The glass manufacturing apparatus according to claim 10, further comprising a dehydration tank disposed in the circulation line for removing H ₂ O gas from the combustion gas. The glass manufacturing apparatus according to claim 8 or 9, wherein a molar ratio x of _CO2 gas to _H2 gas in the overall reaction is greater than 0.00 and less than or equal to 1.00. The glass manufacturing apparatus according to claim 8 or 9, wherein the overall reaction represented by formula (1) or formula (2) includes at least one of (A) a reverse shift reaction, (B) a combination of a methanation reaction and a dry reforming reaction, and (C) a combination of a methanation reaction and a steam reforming reaction. The glass manufacturing apparatus according to claim 8 or 9, wherein the overall reaction represented by formula (1) or formula (2) uses heat recovered from the combustion gas burned by the burner.

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