Exhaust gas treatment method and method for manufacturing glass article

Abstract

The present invention relates to a waste gas treatment method and a method for manufacturing a glass article. The object of the present invention is to provide a waste gas treatment method capable of significantly suppressing the problem of neutralizer adhesion on the wall surface of a stabilizing device. A waste gas treatment method is a waste gas treatment method for treating waste gas generated in the process of manufacturing a glass article, wherein the waste gas treatment method has the following steps: a first step in which waste gas generated when a glass raw material is melted is brought into contact with a cooling aqueous solution to thereby generate a first treated gas; a second step in which the first treated gas is brought into contact with an alkali metal salt or an alkaline earth metal salt to thereby generate a second treated gas; and a third step in which the second treated gas is brought into contact with nitrogen oxide (NO x ) with a reducing agent; and the cooling aqueous solution used in the first step contains urea or ammonia.

Description

Technical Field

[0001] This invention relates to a method for treating waste gas and a method for manufacturing glass articles. Background Technology

[0002] During the manufacturing process of glass products, especially during the formation of molten glass, substances containing hydrogen chloride (HCl) and sulfur oxides (SO₄) are sometimes produced. x ) and nitrogen oxides (NO) x Exhaust gases such as [list of gases]. These exhaust gases need to be properly treated before being released into the atmosphere.

[0003] In the past, exhaust gas treatment equipment was used to treat such exhaust gases. For example, Patent Document 1 describes an exhaust gas treatment device that includes a stabilizing device, a bag filter, and a denitrification device.

[0004] The exhaust gas is cooled in a stabilizing unit, and some of the hydrogen chloride and sulfur oxides contained in the exhaust gas are removed. Additionally, hydrogen chloride and sulfur oxides contained in the exhaust gas are removed in a bag filter. Furthermore, nitrogen oxides contained in the exhaust gas are reduced and removed in a denitrification unit. Therefore, by using such exhaust gas treatment equipment, exhaust gas can be properly treated.

[0005] It should be noted that in previous waste gas treatment equipment, in order to remove acid from the waste gas, neutralizing agents such as sodium hydroxide aqueous solution were sprayed in the stabilization device to neutralize the acid.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-184308 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In recent years, with the increase in glass production capacity, the amount of waste gas emitted from manufacturing equipment has also tended to increase. Therefore, there is a need to further improve the efficiency of waste gas treatment.

[0011] To improve the efficiency of waste gas treatment, it is advisable to increase the amount and / or concentration of the neutralizing agent sprayed in the stabilizing device.

[0012] However, sodium hydroxide aqueous solution, used as a neutralizing agent, has a high viscosity. Therefore, when spraying high concentrations or large quantities of neutralizing agent (sodium hydroxide aqueous solution) into the stabilization unit, the risk of sodium hydroxide adhering to the walls increases. Furthermore, if such adhesion becomes significant, it may block the exhaust gas flow path.

[0013] This invention was made in view of the following background, and its object is to provide a waste gas treatment method that can significantly suppress the problem of neutralizing agent adhesion on the wall surface of a stabilizing device. Furthermore, an object of this invention is to provide a method for manufacturing glass articles utilizing such a waste gas treatment method.

[0014] means for solving problems

[0015] This invention provides a waste gas treatment method for treating waste gas generated during the manufacturing process of glass articles. The waste gas treatment method includes the following steps: a first step, wherein waste gas generated during the melting of glass raw materials is contacted with a cooling aqueous solution to generate a first treated gas; a second step, wherein the first treated gas is contacted with an alkali metal salt or an alkaline earth metal salt to generate a second treated gas; and a third step, wherein the second treated gas is contacted with nitrogen oxides (NOx). x The solution is contacted with a reducing agent, and the cooling aqueous solution used in the first step contains urea or ammonia.

[0016] Invention Effects

[0017] This invention provides a waste gas treatment method that can significantly suppress the adhesion of neutralizing agents to the walls of a stabilizing device. Furthermore, this invention provides a method for manufacturing glass articles utilizing such a waste gas treatment method. Attached Figure Description

[0018] Figure 1 A flowchart illustrating a waste gas treatment method according to an embodiment of the present invention is provided.

[0019] Figure 2 The diagram illustrates, schematically, an example of the configuration of an exhaust gas treatment apparatus for implementing an exhaust gas treatment method according to an embodiment of the present invention.

[0020] Figure 3 A flowchart illustrating a method for manufacturing a glass article according to an embodiment of the present invention is provided.

[0021] Figure 4 A graph summarizing the results of ammonia measurements in the exhaust gas obtained in each example is provided.

[0022] Figure 5 A graph showing the chlorine levels measured at the outlet of the stabilizing unit in each example is provided for summary purposes.

[0023] Figure 6 A graph showing the amount of sulfur dioxide measured at the outlet of the stabilizing device in each example is provided for summary purposes.

[0024] Figure 7A graph summarizing the dechlorination rates obtained in the stabilizing devices in each example is shown.

[0025] Figure 8 A graph summarizing the desulfurization rates obtained in the stabilization units in each example is provided.

[0026] Figure 9 A graph summarizing the denitrification rates obtained in the denitrification devices in each example is provided.

[0027] Figure Labels

[0028] 100 Waste Gas Treatment Equipment

[0029] 110 Melting Furnace

[0030] 120 Stabilizer

[0031] 122 Nozzle

[0032] 126 First Recycling Unit

[0033] 140 bag filter

[0034] 142 Main body

[0035] 146 Second Recycling Unit

[0036] 150 Powder Feeding Device

[0037] 152 Powder Supply Chamber

[0038] 160 Denitrification Unit

[0039] 170 Wet scrubber

[0040] 174 Pipeline

[0041] 180 chimney

[0042] G exhaust gas

[0043] G1~G4 First Processing Gas~Fourth Processing Gas

[0044] S1 First reaction product

[0045] S2, the second reaction product Detailed Implementation

[0046] Hereinafter, one embodiment of the present invention will be described.

[0047] As mentioned earlier, conventional waste gas treatment methods use sodium hydroxide aqueous solution as a neutralizing agent sprayed into the stabilization unit. However, sodium hydroxide aqueous solution has a high viscosity, and spraying high concentrations or large quantities of sodium hydroxide aqueous solution increases the risk of sodium hydroxide adhering to the walls of the stabilization unit.

[0048] Therefore, in one embodiment of the present invention, a waste gas treatment method is provided, which is a waste gas treatment method for treating waste gas generated during the manufacturing process of glass articles, wherein the waste gas treatment method comprises the following steps: a first step, wherein waste gas generated during the melting of glass raw materials is contacted with a cooling aqueous solution to generate a first treated gas; a second step, wherein the first treated gas is contacted with an alkali metal salt or an alkaline earth metal salt to generate a second treated gas; and a third step, wherein the second treated gas is contacted with nitrogen oxides (NOx) x It is in contact with a reducing agent; and the cooling aqueous solution used in the first step contains urea or ammonia.

[0049] In a waste gas treatment method according to an embodiment of the present invention, a cooling aqueous solution containing urea or ammonia (hereinafter collectively referred to as "ammonia-containing aqueous solution") is used in the first step.

[0050] Urea and ammonia solutions have lower viscosity than sodium hydroxide solutions. Therefore, in the first process, when using an ammonia solution as a neutralizing agent, even if the concentration of the ammonia solution is high and / or the quantity is relatively large, the problem of the neutralizing agent adhering to the walls of the stabilizing device can be significantly reduced.

[0051] Therefore, the waste gas treatment method according to one embodiment of the present invention can treat waste gas more effectively than in the past.

[0052] It should be noted that, in one embodiment of the present invention, the ammonia-containing aqueous solution can be used alone or in combination with a sodium hydroxide aqueous solution. In the latter case, a mixed aqueous solution containing urea or ammonia and sodium hydroxide can be used, or the ammonia-containing aqueous solution and the sodium hydroxide aqueous solution can be used separately. Furthermore, the latter case can significantly reduce the concentration and / or spray volume of the sodium hydroxide aqueous solution compared to using the sodium hydroxide aqueous solution alone.

[0053] (A waste gas treatment method according to an embodiment of the present invention)

[0054] Hereinafter, a waste gas treatment method according to one embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

[0055] Figure 1 The diagram schematically illustrates the flow of a waste gas treatment method according to an embodiment of the present invention.

[0056] like Figure 1As shown, a waste gas treatment method according to one embodiment of the present invention includes the following steps: a first step (step S110), wherein the first step is a step of contacting waste gas generated during the melting of glass raw materials with a cooling aqueous solution to generate a first reaction product and a first treated gas, wherein the cooling aqueous solution contains urea or ammonia; a second step (S120), wherein the first treated gas is contacted with an alkali metal salt or an alkaline earth metal salt to generate a second reaction product and a second treated gas; and a third step (S130), wherein the second treated gas is contacted with nitrogen oxides (NOx) x Contact with a reducing agent.

[0057] Figure 2 The diagram schematically illustrates an example of the configuration of an exhaust gas treatment apparatus (hereinafter referred to as "treatment apparatus") for implementing an exhaust gas treatment method according to an embodiment of the present invention.

[0058] like Figure 2 As shown, the processing equipment 100 includes: a melting furnace 110, a stabilizing device 120, a bag filter 140, a denitrification device 160, a wet scrubbing device 170, and a chimney 180.

[0059] The melting furnace 110 is used to melt glass raw materials to form molten glass.

[0060] The stabilizing device 120 is located downstream of the melting furnace 110 and is provided for cooling the waste gas G generated in the melting furnace 110. In addition, the stabilizing device 120 has one or more nozzles 122 capable of spraying a neutralizing agent and a first recovery unit 126 for recovering the product generated by the reaction of the waste gas G with the neutralizing agent (hereinafter referred to as "first reaction product S1").

[0061] A bag filter 140 is disposed downstream of the stabilizing device 120. The bag filter 140 is provided to process the process gas (hereinafter referred to as "first process gas") G1 discharged from the stabilizing device 120. In addition, the bag filter 140 includes: a plurality of main bodies 142, a powder supply device 150 for supplying powder to each main body 142, and a second recovery unit 146 for recovering the product generated in the main body 142 (hereinafter referred to as "second reaction product S2").

[0062] Each main body 142 is provided with a filter cloth (not shown) for forming a flow path of the first processed gas G1. The filter cloth is made of resin such as polytetrafluoroethylene. The powder supply device 150 has multiple powder supply chambers 152, each powder supply chamber 152 being connected to its corresponding main body 142. It should be noted that in Figure 2 In the example shown, the main body 142 and the powder supply chamber 152 are each composed of three sections. However, there is no particular limitation on the number of sections.

[0063] The denitrification unit 160 is located downstream of the bag filter 140. The denitrification unit 160 is provided to treat the processed gas (hereinafter referred to as "second processed gas") G2 discharged from the bag filter 140. Additionally, the denitrification unit 160 has a reducing agent injection nozzle and a catalyst (neither shown). The catalyst may, for example, contain vanadium pentoxide (V₂O₅).

[0064] A wet scrubbing unit 170 is located downstream of the denitrification unit 160. The wet scrubbing unit 170 functions to recover water-soluble components contained in the treated gas (hereinafter referred to as "third treated gas") G3 discharged from the denitrification unit 160. Additionally, the wet scrubbing unit 170 has a nozzle for spraying liquid and a tank for recovering waste liquid (neither shown). The liquid can be, for example, water or an aqueous solution. Furthermore, the wet scrubbing unit 170 may be connected to a pipe 174 for returning the waste liquid recovered into the tank to the stabilization unit 120. It should be noted that the wet scrubbing unit 170 may be omitted in the treatment equipment 100.

[0065] Chimney 180 is provided for discharging the treated gas (hereinafter referred to as "fourth treated gas") G4 from the wet scrubbing unit 170 into the atmosphere. However, in the case where the treatment equipment 100 does not have a wet scrubbing unit 170, third treated gas G3 from the denitrification unit 160 is introduced into chimney 180.

[0066] The following is for reference Figure 2 Each step in a waste gas treatment method (hereinafter referred to as the "first method") according to an embodiment of the present invention will be described.

[0067] (Process S110)

[0068] First, glass raw materials are melted in melting furnace 110 to form molten glass. Waste gas G is generated during the melting of the glass raw materials. This waste gas G contains various components such as chlorine, sulfur, and nitrogen. The chlorine component is mainly hydrogen chloride (HCl), and the sulfur component is mainly sulfur oxides (SO₄). x The nitrogen component is mainly nitrogen oxides (NO). x Exhaust gas G cannot be discharged directly, therefore it should be treated appropriately in the following manner.

[0069] Exhaust gas G is supplied to stabilizing device 120. Exhaust gas G is cooled by passing through stabilizing device 120. The inlet temperature of stabilizing device 120 is, for example, in the range of 700°C to 900°C, and the outlet temperature is, for example, in the range of 200°C to 220°C.

[0070] Additionally, as previously described, one or more nozzles 122 are provided in the stabilizing device 120, and a cooling aqueous solution serving as a neutralizing agent is sprayed from these nozzles 122. The neutralizing agent comprises an "ammonia-containing aqueous solution," that is, an aqueous solution containing urea or ammonia. The "ammonia-containing aqueous solution" has a low viscosity, making it less likely to cause the aforementioned problem, namely, the problem of the neutralizing agent adhering to the inner wall of the stabilizing device 120. Therefore, a higher concentration of the ammonia-containing aqueous solution or a relatively large amount of the ammonia-containing aqueous solution can be used.

[0071] Furthermore, compared to the sodium hydroxide aqueous solution, the ammonia-containing aqueous solution, as the first reaction product S1 generated by the reaction with waste gas G, is less likely to adhere to the inner wall of the stabilizing device 120. Specifically, the ammonia-containing aqueous solution reacts with the chlorine and sulfur components contained in waste gas G to generate ammonium chloride and ammonium sulfate (see reaction formulas (1) to (4) described later). On the other hand, the sodium hydroxide aqueous solution reacts with the chlorine and sulfur components contained in waste gas G to generate sodium chloride and sodium sulfate (see reaction formulas (5) and (6) described later). Moreover, compared to the first reaction product S1 containing sodium chloride and sodium sulfate, the first reaction product S1 containing ammonium chloride and ammonium sulfate has a smaller particle size and better flowability, and therefore is less likely to adhere to the inner wall of the stabilizing device 120.

[0072] The concentration of urea or ammonia in the cooling aqueous solution is preferably 3% to 30% by mass. When the concentration of urea or ammonia is 3% by mass or higher, it can effectively treat hydrogen chloride (HCl) and sulfur oxides (SO₄) contained in waste gas G. x When the concentration of urea or ammonia is below 30% by mass, the viscosity of the cooling aqueous solution is low, making it less likely for the neutralizing agent to adhere to the inner wall of the stabilizing device 120. A more preferable concentration of urea or ammonia is 5% to 25% by mass.

[0073] The cooling aqueous solution preferably also contains sodium hydroxide or magnesium hydroxide. In this case, the concentration of sodium hydroxide or magnesium hydroxide is more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less. At concentrations above this, the viscosity of the cooling aqueous solution increases, which may cause problems with adhesion to the wall surface.

[0074] Furthermore, the molar ratio (hereinafter referred to as "urea addition rate") of the total amount of urea added to the sprayed neutralizing agent (cooling aqueous solution) relative to the total amount of alkali added to the sprayed neutralizing agent (cooling aqueous solution) is preferably 20% or more, more preferably 30% or more. Here, the total amount of alkali added refers to the total number of moles of urea, ammonia, sodium hydroxide, and magnesium hydroxide added to the neutralizing agent. When the urea addition rate is 20% or more, it is possible to effectively treat hydrogen chloride (HCl) and sulfur oxides (SO₄) contained in the waste gas G. x ).

[0075] Furthermore, the molar ratio (hereinafter referred to as "ammonia addition rate") of the total ammonia content in the sprayed neutralizing agent (cooling aqueous solution) to the total alkali content in the sprayed neutralizing agent (cooling aqueous solution) is preferably 30% or more, more preferably 50% or more. When the ammonia addition rate is 30% or more, it is possible to effectively treat hydrogen chloride (HCl) and sulfur oxides (SO₄) contained in the waste gas G. x ).

[0076] It should be noted that different neutralizing agents can be sprayed from each nozzle 122. Alternatively, the same neutralizing agent can be sprayed from each nozzle 122. For example, one nozzle 122 can be used for spraying an ammonia-containing aqueous solution, and another nozzle 122 can be used for spraying a sodium hydroxide aqueous solution. Alternatively, a mixed aqueous solution containing urea or ammonia and sodium hydroxide can be sprayed from a single nozzle 122.

[0077] The sprayed neutralizing agent vaporizes within the stabilizing unit 120 and comes into contact with the chlorine and sulfur components contained in the waste gas G. As a result, a first reaction product S1 and a first treated gas G1 are generated.

[0078] For example, in the case where the neutralizing agent contains urea, it is assumed that hydrogen chloride and sulfur oxides are separated from waste gas G by the following reaction formulas (1) and (2).

[0079] 2HCl+(NH2)2CO+H2O=2NH4Cl+CO2 (1)

[0080] SO3+(NH2)2CO+2H2O=(NH4)2SO4+CO2 (2)

[0081] In addition, when the neutralizing agent contains ammonia, it is believed that hydrogen chloride and sulfur oxides are separated from waste gas G by the following reaction formulas (3) and (4).

[0082] HCl + NH3 = NH4Cl (3)

[0083] SO3 + 2NH3 + H2O = (NH4)2SO4 (4)

[0084] Furthermore, in the case where the neutralizing agent contains sodium hydroxide, it is believed that hydrogen chloride and sulfur oxides are separated from waste gas G by the following reaction formulas (5) and (6), respectively.

[0085] HCl + NaOH = NaCl + H₂O (5)

[0086] SO3 + 2NaOH = Na2SO4 + H2O (6)

[0087] In this manner, a portion of the chlorine and sulfur components are removed from the exhaust gas G in the form of a first reaction product S1 via a stabilizing device 120, and the first treated gas G1 is discharged.

[0088] The first reaction product S1 generated is recovered using the first recovery unit 126.

[0089] (Process S120)

[0090] Next, the first processing gas G1 discharged from the stabilizing device 120 is supplied to the main body 142 of the bag filter 140. The temperature of the main body 142 is, for example, in the range of 180°C to 220°C. As mentioned above, the main body 142 is connected to each powder supply chamber 152 of the powder supply device 150, and powder is supplied from these powder supply chambers 152 to the main body 142.

[0091] The powder is composed of alkali metal salts and / or alkaline earth metal salts. The alkali metal salt is preferably sodium bicarbonate or sodium carbonate. The alkaline earth metal salt is preferably calcium hydroxide, calcium carbonate, or a double salt of calcium carbonate and magnesium carbonate. It should be noted that, in this specification, alkaline earth metal salts are defined as hydroxides containing alkaline earth metals.

[0092] The powder supplied to the main body 142 comes into contact with the chlorine and sulfur components contained in the first processing gas G1. As a result, a second reaction product S2 and a second processing gas G2 are generated. For example, in the case where the powder contains calcium hydroxide, hydrogen chloride and sulfur oxides are separated from the first processing gas G1 by the following reaction formulas (7) and (8), respectively.

[0093] 2HCl + Ca(OH)₂ = CaCl₂ + 2H₂O (7)

[0094] SO3 + Ca(OH)2 = CaSO4 + H2O (8)

[0095] In this manner, a portion of the chlorine and sulfur components are removed from the first processed gas G1 as a second reaction product S2 via a bag filter 140, and the second processed gas G2 is discharged. The second reaction product S2 is recovered using a second recovery unit 146.

[0096] Here, as shown in reaction formula (1) above, the first processing gas G1 contains ammonium chloride (NH4Cl) generated by reaction in step S110. In bag filter 140, the ammonium chloride reacts with the supplied powder (calcium hydroxide) as shown in reaction formula (9) below, thereby converting it into calcium chloride and ammonia.

[0097] 2NH4Cl+Ca(OH)2=CaCl2+2NH3+2H2O (9)

[0098] Therefore, when using calcium hydroxide as a powder, it is assumed that the second processing gas G2 contains ammonia generated through this reaction. This ammonia can then be used in the subsequent process S130.

[0099] Furthermore, as can be seen from reaction formula (9), when the powder supplied to the bag filter 140 is calcium hydroxide, the supplied calcium hydroxide is also consumed during the generation of ammonia. It is known that most of the calcium hydroxide normally supplied to the bag filter 140 remains in an unreacted state. However, in the first method, for example, by using reaction formula (9), the amount of calcium hydroxide remaining in the bag filter 140 in an unreacted state can be significantly suppressed. Therefore, the powder supplied to the bag filter 140 can be utilized more effectively.

[0100] The concentration of sulfur in the second treated gas G2 discharged from bag filter 140, converted to sulfur dioxide (SO2), is, for example, 100 mg / Nm³. 3 The following is a separate point. Additionally, the concentration of chlorine in the second treated gas G2, converted to hydrogen chloride (HCl), is, for example, 100 mg / Nm³. 3 the following.

[0101] (Process S130)

[0102] Next, the second processing gas G2 discharged from the bag filter 140 is supplied to the denitrification unit 160.

[0103] It should be noted that the second processing gas G2 can be heated before being supplied to the denitrification unit 160. Heating the second processing gas G2 can improve the reaction efficiency within the denitrification unit 160. The heating temperature can be, for example, in the range of 250°C to 300°C.

[0104] When the second processing gas G2 is supplied to the denitrification unit 160, a reducing agent is injected through the injection nozzle. The reducing agent is preferably ammonia, ammonia water, or an aqueous solution of urea. When the second processing gas G2 comes into contact with the reducing agent (ammonia or ammonia water), for example, the reactions shown in the following reaction formulas (10) and (11) occur.

[0105] NO + NO₂ + 2NH₃ = 2N₂ + 3H₂O (10)

[0106] SO3 + 2NH3 + H2O = (NH4)2SO4 (11)

[0107] Thus, nitrogen oxides and sulfur oxides in the second processing gas G2 are removed, and the third processing gas G3 is generated.

[0108] It should be noted that, as mentioned above, the second processing gas G2 sometimes contains ammonia (see reaction formula (9)). This ammonia can be used for reactions with nitrogen oxides and sulfur oxides. In this case, the amount of reducing agent supplied from the injection nozzle can be suppressed in the denitrification unit 160.

[0109] The temperature of the third treated gas G3 discharged from the denitrification unit 160 is, for example, in the range of 250°C to 300°C. Furthermore, the concentration of nitrogen oxides contained in the third treated gas G3 is, for example, 800 mg / Nm³. 3 the following.

[0110] Then, if necessary, the third treatment gas G3 discharged from the denitrification unit 160 can be supplied to the wet scrubbing unit 170. By using the wet scrubbing unit 170, residual sulfur and chlorine components that could not be removed in the upstream unit are removed. Specifically, when the third treatment gas G3 is supplied to the wet scrubbing unit 170, a liquid such as water is sprayed from a nozzle. As a result, sulfur and chlorine components dissolve in the water, allowing these residual components to be recovered into a tank. The aqueous solution recovered into the tank can be returned to the stabilization unit 120 via pipe 174. In this case, the amount of waste liquid from waste treatment can be reduced.

[0111] Then, the fourth processing gas G4 discharged from the wet scrubbing unit 170 is released into the atmosphere via the chimney 180. To prevent condensation, the fourth processing gas G4 may also be supplied to the chimney 180 after being heated to 200°C to 250°C.

[0112] However, as mentioned above, the wet scrubbing unit 170 is not a necessary component and can be omitted. In this case, the third processing gas G3 from the denitrification unit 160 is directly supplied to the chimney 180, or the third processing gas G3 from the denitrification unit 160 is heated before being supplied to the chimney 180 to prevent condensation.

[0113] The above describes how, through this process, waste gas G can be appropriately treated. Taking the first method as an example, a waste gas treatment method according to an embodiment of the present invention has been described.

[0114] However, the above description is only one example, and the waste gas treatment method according to one embodiment of the present invention may also have other steps. For example, the second reaction product S2 recovered by the second recovery unit 146 in step S120 of the first method can be returned to the melting furnace 110 and melted together with the glass raw material. In this case, the amount of waste discharged from the treatment equipment 100 can be significantly reduced. In addition, modifications, changes, and additions to each step can be made.

[0115] (A method for manufacturing a glass article according to an embodiment of the present invention)

[0116] Next, refer to Figure 3 A method for manufacturing a glass article according to one embodiment of the present invention will be described. Figure 3 The diagram schematically illustrates the process of a method for manufacturing a glass article according to one embodiment of the present invention.

[0117] like Figure 3 As shown, a method for manufacturing a glass article according to an embodiment of the present invention (hereinafter referred to as the "manufacturing method") includes the following steps: a step of melting glass raw materials to form molten glass (S210); a step of shaping the molten glass to form shaped glass (S220); and a step of slowly cooling the shaped glass to obtain a glass article (S230).

[0118] The following is a description of each process.

[0119] (Process S210)

[0120] First, use as described above Figure 2 The melting furnace 110 shown melts the glass raw material to form molten glass.

[0121] (Process S220)

[0122] Next, the molten glass is shaped. There are no particular restrictions on the shaping method; conventional methods can be used. For example, the float glass method or the fusion method can be used to shape the glass ribbon.

[0123] (Process S230)

[0124] Next, the shaped glass is slowly cooled to room temperature. Then, the slowly cooled glass is cut to the desired size to produce a glass article.

[0125] Here, waste gas is generated during the implementation of the manufacturing method, particularly in the process of forming molten glass (step S210). This waste gas is treated using a waste gas treatment method according to an embodiment of the present invention. For example, the waste gas can be treated using the aforementioned first method. By treating the waste gas using the waste gas treatment method according to an embodiment of the present invention, the chlorine, sulfur, and nitrogen components contained in the waste gas can be appropriately removed.

[0126] There are no particular restrictions on the composition of the glass articles to be manufactured. However, the manufacturing method is suitable for the manufacture of alkali-free glass for the following reasons: Alkali-free glass refers to glass in which the total content of alkali metal oxides is less than 0.1% by mass.

[0127] In the manufacture of alkali-free glass, in step S210, glass raw materials containing a chlorine-containing clarifying agent are added to the melting furnace 110 to remove air bubbles contained in the molten glass. Therefore, waste gas containing the corresponding chlorine component may be generated in the manufacturing process of alkali-free glass.

[0128] Therefore, in the manufacturing method, an ammonia-containing aqueous solution that does not easily adhere to the wall surface is used as a cooling aqueous solution sprayed in the stabilizing device 120. Thus, even when the exhaust gas contains a high concentration of chlorine, the exhaust gas can be effectively treated by using a higher concentration and / or a relatively large amount of ammonia-containing aqueous solution.

[0129] For example, alkali-free glass, expressed as a percentage by mass based on oxides, contains: 54%–66% SiO2, 10%–23% Al2O3, 6%–12% B2O3, and 8%–26% MgO+CaO+SrO+BaO.

[0130] To obtain a high strain point, for example, alkali-free glass contains, by mass % based on oxides, 54%–68% SiO2, 10%–25% Al2O3, 0.1%–5.5% B2O3, and 8%–26% MgO+CaO+SrO+BaO.

[0131] The Cl content in alkali-free glass is, for example, 0.1% to 0.35% by mass.

[0132] [Example]

[0133] The embodiments of the present invention will be described below. It should be noted that in the following description, Examples 1 to 5 are embodiments, and Example 11 is a comparative example.

[0134] (Example 1)

[0135] Waste gas discharged from the melting furnace is treated using waste gas treatment equipment. The aforementioned equipment is used as the waste gas treatment equipment. Figure 2 The equipment shown is configured as follows. The operating conditions of each component of the waste gas treatment equipment are described below.

[0136] [Melting Furnace]

[0137] Glass melting temperature: 1600℃

[0138] Glass raw materials: Raw materials for manufacturing alkali-free glass (AN100 from AGC Corporation).

[0139] Exhaust gas temperature: 1200℃

[0140] [Stabilizing device]

[0141] Inlet temperature of the exhaust gas stabilization device: 750℃

[0142] Neutralizing agent 1: A 10% by mass urea aqueous solution

[0143] Neutralizer 1 flow rate: 5L / hour

[0144] Moles of neutralizing agent 1: 505 moles / hour

[0145] Neutralizing agent 2: 0.61% by mass sodium hydroxide aqueous solution

[0146] Neutralizer 2 flow rate: 3300 L / hour

[0147] Moles of neutralizing agent 2: 503 moles / hour

[0148] Total alkali addition: 1008 moles / hour

[0149] Urea addition rate: 50%

[0150] Exhaust gas stabilization device outlet temperature: 210℃

[0151] [Bag Filter]

[0152] Inlet temperature of the bag filter for exhaust gas: 210℃

[0153] Powder material: calcium hydroxide

[0154] Powder supply rate: 1.5 tons / day

[0155] Exhaust gas bag filter outlet temperature: 190℃

[0156] [Denitrification unit]

[0157] Inlet temperature of the denitrification unit for exhaust gas: 280℃

[0158] Reducing agent: Ammonia (supply rate = 300L / min)

[0159] The outlet temperature of the denitrification unit for exhaust gas is 280℃.

[0160] [Wet Filter Unit]

[0161] Inlet temperature of the wet scrubbing unit for exhaust gas: 80℃

[0162] Spray liquid: Water (supply rate = 3000L / hour)

[0163] The outlet temperature of the wet scrubbing unit for exhaust gas is 70℃.

[0164] (Example 2~Example 5)

[0165] The exhaust gas was treated using the same equipment as in Example 1. However, in Examples 2 to 5, the conditions of the neutralizing agent sprayed in the stabilizing device were changed, as shown in Table 1 below.

[0166] Other operating conditions are the same as in Example 1.

[0167] (Example 11)

[0168] The exhaust gas was treated using the same equipment as in Example 1. However, in Example 11, neutralizing agent 1 (urea aqueous solution) was not sprayed into the stabilizing unit. That is, only neutralizing agent 2 (sodium hydroxide aqueous solution) was sprayed under the conditions specified in Table 1 below.

[0169] Other operating conditions are the same as in Example 1.

[0170] Table 1

[0171]

[0172] (result)

[0173] In each example, the following items were evaluated.

[0174] (The behavior of ammonia)

[0175] In Examples 1 through 5, the ammonia content in the waste gas was measured at various locations within the waste gas treatment equipment. The waste gas referred to here is waste gas G, the first treated gas G1, the second treated gas G2, and the fourth treated gas G4.

[0176] exist Figure 4 The results of ammonia concentration measurements in exhaust gases obtained in each example are shown. The measurement locations are set as the inlet of the stabilizer (hereinafter referred to as "Location A"), the outlet of the stabilizer (hereinafter referred to as "Location B"), the outlet of the bag filter (hereinafter referred to as "Location C"), and immediately in front of the chimney (hereinafter referred to as "Location D").

[0177] like Figure 4 As shown, the amount of ammonia in the exhaust gas exhibits characteristic behavior. That is, the amount of ammonia decreases from position A to position B, then increases again at position C, and then decreases again at position D.

[0178] The behavior from position A to position B corresponds to the reaction within the stabilizing device. That is, the urea aqueous solution sprayed within the stabilizing device decomposes into ammonia immediately after spraying. Therefore, at position A, the ammonia level is high. However, the generated ammonia reacts with the chlorine and sulfur components contained in the exhaust gas, for example, as in the aforementioned reactions (3) and (4), and the generated ammonia is consumed. Therefore, at position B, the ammonia level decreases.

[0179] On the other hand, the behavior from position B to position C corresponds to the reaction within the bag filter. That is, within the bag filter, for example, as in the aforementioned reaction formula (9), the ammonium salt reacts with calcium hydroxide to generate ammonia. Therefore, at position C, the amount of ammonia increases again.

[0180] Furthermore, the behavior from position C to position D corresponds to the reaction within the denitrification unit. That is, as in the aforementioned reaction formulas (10) and (11), the ammonia regenerated at position C is consumed by the reaction within the denitrification unit. Therefore, at position D, the amount of ammonia decreases.

[0181] Therefore, it can be seen that in the waste gas treatment processes of Examples 1 to 5, the ammonia gas undergoes characteristic increases and decreases repeatedly along the flow of the waste gas.

[0182] (Effect of waste gas treatment)

[0183] exist Figure 5 The table summarizes the chlorine levels measured at the stabilization unit outlet (location B) for each example. Figure 5 In the diagram, the horizontal axis represents the total amount of urea and sodium hydroxide added during spraying within the stabilizing unit, i.e., the total alkali addition (mol / h). The vertical axis represents the amount of chlorine (mol / h) at the stabilizing unit outlet (position B).

[0184] Depend on Figure 5 It can be seen that the more the total alkali added, the lower the chlorine content in the exhaust gas (first treated gas G1) at location B becomes. The same tendency was observed when the neutralizing agent used in the spray was only sodium hydroxide (Example 11). Therefore, based on this result, it can be said that urea sprayed within the stabilizing unit has at least the same effect on chlorine removal as sodium hydroxide.

[0185] exist Figure 6 The table summarizes the sulfur dioxide levels measured at the stabilization unit outlet (location B) for each example. Figure 6 In the diagram, the horizontal axis represents the total amount of alkali added within the stabilizing unit (mol / h). The vertical axis represents the amount of sulfur dioxide (mol / h) at the stabilizing unit outlet (position B).

[0186] Depend on Figure 6 It can be seen that, regarding the sulfur dioxide contained in the exhaust gas at location B, the more the total alkali added, the more the sulfur dioxide content tends to decrease. Therefore, based on this result, it can be said that the urea sprayed in the stabilizing device has at least the same effect as sodium hydroxide in removing sulfur dioxide.

[0187] exist Figure 7 The diagram shows the dechlorination rates obtained in the stabilizing units in each example. Figure 7 It can be seen that in Examples 1 to 5, where urea was sprayed, a dechlorination rate equal to or higher than that in Example 11, where sodium hydroxide was sprayed only, was obtained. It should be noted that the dechlorination rate was calculated according to the following formula (12).

[0188] Dechlorination rate (%) = 1 - Cl concentration at the bag filter inlet / Cl concentration at the stabilization device inlet

[0189] ………(12)

[0190] exist Figure 8 The figure shows the desulfurization rates obtained in the stabilization units in each example. Figure 8 It can be seen that in Examples 1 to 5, where urea was sprayed, a desulfurization rate equal to or higher than that in Example 11, where sodium hydroxide was sprayed only, can be obtained. It should be noted that the desulfurization rate is calculated according to the following formula (13).

[0191] Desulfurization rate (%) = 1 - SO2 concentration at the inlet of the bag filter / SO2 concentration at the inlet of the stabilization unit………(13)

[0192] exist Figure 9 The denitrification rates obtained in the denitrification devices in each example are shown. It should be noted that the denitrification rate is calculated according to the following formula (14).

[0193] Denitrification rate (%) = 1 - NO immediately preceding the chimney x NO concentration at bag filter outlet x Concentration………(14)

[0194] Depend on Figure 9 It is evident that in Examples 1 to 5, where urea was sprayed, a higher denitrification rate was obtained than that in Example 11, where only sodium hydroxide was sprayed. This is believed to be because, as mentioned earlier, ammonia gas was generated in the bag filter in Examples 1 to 5. That is, it is believed that in the denitrification unit, in addition to the sprayed ammonia gas, the ammonia gas generated in the previous process also contributes to the denitrification reaction, thus enabling a high denitrification rate.

[0195] The following Table 2 summarizes the dechlorination rate, desulfurization rate, and denitrification rate obtained in each example in the stabilization unit.

[0196] Table 2

[0197]

[0198] Therefore, it can be seen that in the waste gas treatment processes of Examples 1 to 5, the same or better effects as the waste gas treatment process of Example 11 can be achieved for any one of the dechlorination rate, desulfurization rate and denitrification rate.

[0199] The above confirms that even when using an ammonia-containing aqueous solution as a neutralizing agent sprayed in the stabilizing device, the exhaust gas can be properly treated.

Claims

1. A waste gas treatment method, which is a waste gas treatment method for treating waste gas generated during the manufacturing process of glass articles, wherein, The waste gas treatment method includes the following steps: In the first process, the waste gas generated during the melting of glass raw materials is brought into contact with an aqueous cooling solution to generate a first processing gas. The second process involves contacting the first processed gas with an alkali metal salt or an alkaline earth metal salt to generate a second processed gas. and The third step involves reacting the second processing gas with nitrogen oxides (NO). x Contact with a reducing agent, and The cooling aqueous solution used in the first process contains urea or ammonia. The temperature of the first processed gas after the first step is in the range of 200℃ to 220℃. In the first step, the urea or ammonia reacts with the chlorine contained in the waste gas. The concentration of urea or ammonia in the cooling aqueous solution is 3% to 30% by mass.

2. A waste gas treatment method, which is a waste gas treatment method for treating waste gas generated during the manufacturing process of glass articles, wherein, The waste gas treatment method includes the following steps: In the first process, the waste gas generated during the melting of glass raw materials is brought into contact with an aqueous cooling solution to generate a first processing gas. The second process involves contacting the first processed gas with an alkali metal salt or an alkaline earth metal salt to generate a second processed gas. and The third step involves reacting the second processing gas with nitrogen oxides (NO). x Contact with a reducing agent, and The cooling aqueous solution used in the first process contains urea or ammonia. In the first step, the urea or ammonia reacts with the chlorine contained in the waste gas. The concentration of urea or ammonia in the cooling aqueous solution is 3% to 30% by mass.

3. The waste gas treatment method as described in claim 1 or 2, wherein, The cooling aqueous solution also contains sodium hydroxide or magnesium hydroxide.

4. The waste gas treatment method as described in claim 3, wherein, The concentration of sodium hydroxide or magnesium hydroxide is less than 2.0% by mass.

5. The waste gas treatment method as described in claim 1 or 2, wherein, The molar ratio of urea added to the cooling aqueous solution to the total alkali added in the cooling aqueous solution is more than 20%.

6. The waste gas treatment method as described in claim 1 or 2, wherein, The alkali metal salt is sodium bicarbonate or sodium carbonate.

7. The waste gas treatment method as described in claim 1 or 2, wherein, The alkaline earth metal salt is calcium hydroxide, calcium carbonate, or a double salt of calcium carbonate and magnesium carbonate.

8. The waste gas treatment method as described in claim 1 or 2, wherein, The reducing agent is ammonia gas, ammonia water, or an aqueous solution of urea.

9. The waste gas treatment method as described in claim 1 or 2, wherein, The reaction products generated in the second step are melted together with the glass raw material.

10. A manufacturing method for a glass article, wherein, The manufacturing method comprises the following steps: The process of melting glass raw materials to form molten glass; The process of shaping the molten glass to form shaped glass; and The process of slowly cooling the shaped glass to obtain a glass article, and The waste gas generated in the process of forming molten glass is treated using the waste gas treatment method according to any one of claims 1 to 9.

11. The manufacturing method as described in claim 10, wherein, The glass article is made of alkali-free glass.

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