WO2017094417A1 - フッ素元素を含有する排ガスの処理方法 - Google Patents
フッ素元素を含有する排ガスの処理方法 Download PDFInfo
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- WO2017094417A1 WO2017094417A1 PCT/JP2016/082239 JP2016082239W WO2017094417A1 WO 2017094417 A1 WO2017094417 A1 WO 2017094417A1 JP 2016082239 W JP2016082239 W JP 2016082239W WO 2017094417 A1 WO2017094417 A1 WO 2017094417A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1406—Multiple stage absorption
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1456—Removing acid components
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1493—Selection of liquid materials for use as absorbents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/68—Halogens or halogen compounds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/75—Multi-step processes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/77—Liquid phase processes
- B01D53/79—Injecting reactants
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
- B01D2252/10—Inorganic absorbents
- B01D2252/103—Water
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
- B01D2252/20—Organic absorbents
- B01D2252/205—Other organic compounds not covered by B01D2252/00 - B01D2252/20494
- B01D2252/2056—Sulfur compounds, e.g. Sulfolane, thiols
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/20—Halogens or halogen compounds
- B01D2257/202—Single element halogens
- B01D2257/2027—Fluorine
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/20—Halogens or halogen compounds
- B01D2257/204—Inorganic halogen compounds
- B01D2257/2047—Hydrofluoric acid
Definitions
- the present invention treats an exhaust gas containing elemental fluorine and discharges a treatment gas in which fluorine-based gases such as fluorine gas (F 2 ), oxygen difluoride (OF 2 ), and hydrogen fluoride (HF) are reduced. Further, the present invention relates to a method for treating exhaust gas containing elemental fluorine.
- fluorine-based gases such as fluorine gas (F 2 ), oxygen difluoride (OF 2 ), and hydrogen fluoride (HF) are reduced.
- fluorine-based gases such as fluorine gas (F 2 ), oxygen difluoride (OF 2 ), and hydrogen fluoride (HF) are reduced. Further, the present invention relates to a method for treating exhaust gas containing elemental fluorine.
- Fluorine compounds are used in large amounts in various fields in the production of semiconductors, liquid crystals, etc., as raw materials for chemicals and polymer materials, or for the purpose of surface modification.
- fluorine-based gases In particular, in manufacturing processes of semiconductors and liquid crystals, etching, cleaning gases, and the like have conventionally been used as F 2 , NF 3 , SiF 4 , COF 2 , SF 6 , fluorocarbon (CF 4 , C 2 F 6 , C 4 F 6, etc. ) And other fluorine-based gases are used.
- a gas derived from the used fluorine-based gas or a gas containing a fluorine element generated by a reaction is discharged as exhaust gas.
- a gas containing a very high concentration of fluorine element may be discharged as exhaust gas.
- a wet scrubber using an aqueous alkali solution such as water or sodium hydroxide is excellent as a method for treating a large amount of gas at a low cost.
- a more toxic oxygen difluoride (OF 2 ) is used. It is known to be a by-product.
- Oxygen difluoride has an ACGIH permissible concentration (TLV) of 0.05 ppm, which is very toxic, and once produced, it is difficult to remove with water or an aqueous alkaline solution, resulting in a problem that it is discharged from exhaust gas.
- Patent Document 1 discloses a method using a mixed liquid of alkali sulfite and caustic alkali as an absorbing liquid
- Patent Document 2 discloses sodium hydroxide or the like.
- a method using an absorbing solution containing a mixture of a basic compound and a sulfur-based reducing agent such as sodium thiosulfate is disclosed.
- Patent Document 3 discloses a base such as an alkali metal hydroxide and a thiosulfate or A method using a liquid containing an alkali metal nitrite is disclosed.
- Patent Document 4 discloses that an oxidizing gas such as chlorine gas or fluorine gas is exhausted by using a wet treatment in a packed tower packed with water-insoluble sulfite without using a compound containing sodium ions or the like. Is disclosed.
- Patent Document 5 discloses a method in which exhaust gas is reacted with water vapor under heating to decompose it into hydrogen fluoride and oxygen.
- the reaction since the reaction is performed at a high temperature of 300 to 400 ° C., the influence of corrosion by high-temperature hydrogen fluoride gas or the like is large, the material of the reactor is limited, and it is difficult to adopt industrially. It was.
- JP-A-2-233122 JP 2006-231105 A Special table 2013-539717 gazette JP 2000-176243 A JP 2006-289238 A
- the present invention efficiently treats exhaust gas containing elemental fluorine by a wet method to sufficiently remove toxic fluorine-based gases such as fluorine gas, oxidizing gas such as oxygen difluoride, and acidic gas such as hydrogen fluoride. It is an object of the present invention to provide a method for treating exhaust gas containing elemental fluorine, which is a reduced treatment gas.
- the present invention relates to the following items [1] to [7].
- [1] having a first step of contacting an exhaust gas containing elemental fluorine with water, and a second step of contacting a gas component discharged from the first step with a basic aqueous solution containing a reducing agent.
- [2] Treatment of exhaust gas containing fluorine element as described in [1], wherein the exhaust gas containing elemental fluorine contains fluorine gas (F 2 ) and / or hydrogen fluoride (HF) Method.
- [3] The method for treating an exhaust gas containing elemental fluorine according to [1] or [2], wherein the reducing agent is a sulfur-based reducing agent.
- the method for treating exhaust gas containing elemental fluorine when exhaust gas containing elemental fluorine is efficiently treated by a wet method, and exhaust gas containing fluorine-based gas such as fluorine gas at a high concentration is treated.
- fluorine-based gas such as fluorine gas
- oxidizing gas such as oxygen difluoride
- acidic gas such as hydrogen fluoride
- the treatment of the exhaust gas containing elemental fluorine is performed in two specific steps, so that the fluorine-based gas in the exhausted treatment gas can be reduced to a high level and includes a reducing agent used as a chemical solution.
- the amount of basic aqueous solution used can be greatly reduced, and it is economical and efficient. Further, in the present invention, even when hydrogen fluoride is contained at a high concentration in the exhaust gas containing elemental fluorine, the amount of chemical solution used can be suppressed to a small amount.
- a fluorine gas (F 2) concentration in the exhaust gas when contacted with water in the first step was 40% by volume or less, difluoride gas component discharged from the first step
- the oxygen (OF 2 ) concentration can be suppressed, the processing load in the second step can be further reduced, and the exhaust gas can be processed efficiently.
- FIG. 1 shows a schematic diagram of an example of an apparatus for carrying out the method for treating an exhaust gas containing elemental fluorine according to the present invention.
- the method for treating exhaust gas containing elemental fluorine comprises a first step of contacting exhaust gas containing elemental fluorine with water, and a gas component discharged from the first step, a basic aqueous solution containing a reducing agent. And a second step of contacting with.
- First step In the first step, the exhaust gas containing elemental fluorine is brought into contact with water.
- exhaust gas containing a fluorine element such as industrial exhaust gas generated in a process using a fluorine-based gas or a process involving generation of a fluorine-based gas can be treated without any particular limitation.
- the exhaust gas to be treated in the present invention may contain an oxidizing gas such as oxygen difluoride (OF 2 ) and / or an acidic gas such as hydrogen fluoride (HF).
- the fluorine gas and water in the exhaust gas react rapidly to generate hydrogen fluoride and oxygen as shown in the reaction formula (1).
- the exhaust gas when contacting with water preferably has a fluorine gas (F 2 ) concentration of 40% by volume or less, more preferably 30% by volume or less.
- F 2 fluorine gas
- the fluorine gas (F 2 ) concentration in the exhaust gas is within the above range, the fluorine gas (F 2 ) in the exhaust gas can be sufficiently removed in the first step, and ozone (O 3 ) or oxygen difluoride can be removed.
- Generation of (OF 2 ) can be suitably suppressed, and a sufficient exhaust gas treatment can be achieved by reducing the load of the second step described later.
- the fluorine gas (F 2 ) concentration in the exhaust gas is diluted with an inert gas such as air before contacting with water. It is preferable to adjust to 40 volume% or less by the method.
- the inert gas means a gas that does not substantially react with the basic aqueous solution containing the components in the exhaust gas, water, and the reducing agent used in the second step described later, and does not hinder the reaction. Examples thereof include air, nitrogen, and rare gas.
- a conventionally known method for bringing the gas and liquid into contact with each other can be adopted without any particular limitation.
- a method using an apparatus such as an absorption tower in which at least a part of the gas component is absorbed by the liquid component by bringing the liquid component into contact with each other can be preferably employed.
- a method using a known absorption tower equipped with devices such as a spray tower, a plate tower, a packed tower, and a jet scrubber can be preferably adopted, because the structure is simple and the absorption efficiency is good.
- a method using a packed tower is particularly preferred. The method using such an apparatus can be similarly employed in the second step described later.
- fluorine gas (F 2 ) contained in the exhaust gas reacts with water by bringing the exhaust gas containing elemental fluorine into contact with water, so that hydrogen fluoride (HF) or two Converted to fluorinated oxygen (OF 2 ). Further, hydrogen fluoride (HF) contained in the exhaust gas and hydrogen fluoride (HF) generated by the reaction of fluorine gas (F 2 ) and water are easily absorbed by water.
- the exhaust gas to be treated contains a high concentration of hydrogen fluoride (HF)
- the use of a basic aqueous solution containing a reducing agent used in the second step can be largely removed in the first step. The amount can be suppressed.
- the gas containing a fluorine gas and / or hydrogen fluoride can be used suitably as exhaust gas containing a fluorine element.
- fluorine gas (F 2 ), hydrogen fluoride (HF) and the like in the exhaust gas are reduced, and the gas component containing the generated oxygen difluoride (OF 2 ) and the like is discharged. .
- the gas component discharged in the first process is sent to the second process.
- the water in contact with the exhaust gas can be circulated and used.
- the concentration of absorbed hydrogen fluoride (HF) increases as the exhaust gas is treated, the exhaust gas is used in large quantities or continuously.
- the method for exchanging the water as the absorbing solution may be batch or continuous, but in order to stabilize the conditions in the second step, it is preferable to keep the concentration of hydrogen fluoride (HF) in the absorbing solution constant. It is preferable to perform water exchange continuously.
- oxygen difluoride (OF 2) increased concentrations of are suitably suppressed.
- concentration of oxygen difluoride (OF 2 ) in the gas component discharged from the first step is preferably 5% by volume or less, more preferably 1% by volume or less.
- ⁇ Second step> the gas component discharged from the first step is brought into contact with a basic aqueous solution containing a reducing agent.
- the gas component discharged from the first step to be subjected to the second step usually includes oxygen difluoride (OF 2 ) contained in the exhaust gas or generated in the first step, and entrained hydrogen fluoride (HF) and the like.
- the gas component discharged from the first step may include fluorine gas (F 2 ) that has not been reacted or is entrained in the first step.
- the concentration of fluorine gas in the gas component introduced into the second step is preferably 5% by volume or less, and more preferably 1% by volume or less.
- the concentration of oxygen difluoride (OF 2 ) in the gas component introduced into the second step is not particularly limited, but is preferably 5% by volume or less, and preferably 1% by volume or less. More preferred.
- the fluorine gas (F 2 ) concentration in the exhaust gas when contacting with water is 40% by volume or less, the OF 2 concentration in the gas component discharged from the first step is sufficiently set.
- the initial exhaust gas does not contain oxygen difluoride (OF 2 )
- it can be usually 5% by volume or less.
- the concentration of oxygen difluoride (OF 2 ) in the gas component discharged from the first process is high, the gas component may be appropriately diluted with an inert gas and then introduced into the second process.
- oxygen difluoride (OF 2 ) in the introduced gas component reacts with the reducing agent to form hydrogen fluoride (HF), and HF and oxygen difluoride (HF) in the introduced gas component ( Hydrogen fluoride (HF) produced from OF 2 ) is removed by reaction with a base.
- the basic aqueous solution containing the reducing agent used in the second step is an aqueous solution in which the reducing agent and the base are dissolved in water, and is used as an absorbing solution.
- a reducing agent capable of reducing oxygen difluoride (OF 2 ) can be used without particular limitation.
- thiosulfates such as sodium thiosulfate, ammonium thiosulfate, and potassium thiosulfate
- sodium sulfite, sulfite Sulfites such as potassium and ammonium sulfite
- chlorides such as potassium chloride and sodium chloride
- bromides such as potassium bromide
- iodides such as potassium iodide
- nitrites such as sodium nitrite and potassium nitrite
- formic acid and sodium formate It can be selected from formate such as potassium formate; oxalic acid, hydrazine and the like.
- a sulfur-based reducing agent is preferably used, and thiosulfate and sulfite are more
- the concentration of the reducing agent depends on conditions such as oxygen difluoride (OF 2 ) concentration in the gas component to be contacted, but is preferably 1 to 20% by mass in the basic aqueous solution containing the reducing agent. More preferably, it is ⁇ 10% by mass.
- OF 2 oxygen difluoride
- a base capable of removing hydrogen fluoride (HF) can be used without particular limitation, but a metal hydroxide is preferably used, and sodium hydroxide or potassium hydroxide is more preferably used.
- the concentration of the base depends on conditions such as the concentration of hydrogen fluoride (HF) in the gas component to be contacted, but the liquidity of the basic aqueous solution containing the reducing agent is preferably maintained alkaline, preferably pH 8 As described above, it is more preferable that the pH is 9 or more.
- HF hydrogen fluoride
- a conventionally known method of bringing the gas and liquid into contact is not particularly limited, as in the first step.
- a method using an apparatus such as an absorption tower that allows the liquid component to absorb at least a part of the gas component by contacting the gas and liquid can be preferably employed.
- a method using a known absorption tower equipped with devices such as a spray tower, a plate tower, a packed tower, and a jet scrubber can be preferably adopted, because the structure is simple and the absorption efficiency is good.
- a method using a packed tower is particularly preferred.
- a method using the same device may be adopted, or a method using different devices may be adopted.
- a basic aqueous solution containing a reducing agent used as an absorbing solution can usually be circulated and used in an absorption tower.
- concentration of the reducing agent and the base in the aqueous solution decreases and the absorbed reaction product concentration increases as the processing of the introduced gas components proceeds.
- Exchanges may be made.
- the exchange of the basic aqueous solution containing the reducing agent may be performed in a batch or continuously, but the concentration of the fluorine-based harmful gas contained in the gas introduced into the second step is originally low. Since the change of the reducing agent concentration or the base concentration in the basic aqueous solution containing the reducing agent is small, the exchange in a batch is usually economical.
- the gas component (process gas) discharged from the second step of the present invention is sufficiently a fluorine-based harmful gas such as fluorine gas (F 2 ), oxygen difluoride (OF 2 ), hydrogen fluoride (HF), etc. It has been removed and can be substantially free of fluorine-based gas.
- the oxygen difluoride (OF 2 ) concentration in the gas component discharged from the second step of the present invention is preferably 1 ppm by volume or less, more preferably 0.5 ppm by volume or less.
- the fluorine gas (F 2 ) concentration in the gas component discharged from the second step of the present invention is preferably 1 ppm by volume or less, more preferably 0.5 ppm by volume or less.
- the hydrogen fluoride (HF) concentration in the gas component discharged from the second step of the present invention is preferably 3 ppm by volume or less, more preferably 1.5 ppm by volume or less.
- the total concentration of fluorine gas (F 2 ) and oxygen difluoride (OF 2 ) in the gas is analyzed by a method in which a specified amount of gas is absorbed in an aqueous potassium iodide solution and titrated with sodium thiosulfate (iodine titration method). Asked.
- the lower limit of quantification can be adjusted by increasing the amount of gas to be absorbed, and 0.05 ppm by volume or more was measured as the combined concentration of fluorine and oxygen difluoride.
- the oxygen difluoride is quantified using the FT-IR (Fourier transform infrared absorption photometry) method, and the fluorine gas and difluoride are analyzed.
- the fluorine gas concentration was determined by subtracting the oxygen difluoride concentration from the total concentration of oxygen.
- the lower limit of quantification of the oxygen difluoride concentration is 0.5 ppm by volume.
- the hydrogen fluoride concentration was quantified using the FT-IR method.
- the lower limit of quantification of the hydrogen fluoride concentration is 0.5 ppm by volume using a 15 cm gas cell.
- Example 1 A first absorption tower (2) having a diameter of 500 mm in which packed bed 1 (3) is packed with a cascade mini-ring as a packing height of 4 m, and packed bed 2 (11) is packed with a cascade mini-ring as a packing height.
- the exhaust gas was treated using an apparatus including a second absorption tower (10) having a diameter of 500 mm and filled with 4 m.
- a schematic diagram is shown in FIG.
- the circulating liquid tank 2 (12) has a KOH concentration of 2 mass% as a base and potassium sulfite (K 2 SO 3 ) as a reducing agent at a concentration of 12 mass%.
- K 2 SO 3 potassium sulfite
- the exhaust gas to be treated was a gas containing 25% by volume of F 2 , 10% by volume of HF, and not containing OF 2 , and the balance was nitrogen gas. This was introduced at 30 m 3 / hr from the exhaust gas introduction pipe (1) into the first absorption tower (2) performing the first step.
- the exhaust gas introduced into the first absorption tower (2) is in sufficient contact with the water released from the shower nozzle 1 (8) in the first absorption tower (2) having the packed bed 1 (3), The gas component after contact is discharged from the top of the first absorption tower (2), and the discharged gas component is introduced into the second absorption tower (10) performing the second step through the exhaust gas introduction pipe 9. .
- Gas component introduced into the second absorption tower is discharged (10) from the first absorption tower (2), the F 2 2,000 ppm by volume, 1,300 ppm by volume of HF, OF 2 4,100 volumes The gas contained ppm.
- the gas component introduced into the second absorption tower (10) includes a basic aqueous solution containing a reducing agent released from the shower nozzle 2 (14) in the second absorption tower (10) having the packed bed 2 (11). Full contact.
- the gas component after contacting with the basic aqueous solution containing the reducing agent was discharged from the top of the second absorption tower (10) through the processing gas discharge pipe (15) as a processing gas.
- the concentration of each fluorine-based gas component in the processing gas discharged from the processing gas discharge pipe (15) and the chemical solution (basic aqueous solution containing a reducing agent) in the second step performed on the second absorption tower (10) side The amount used is shown in Table 1. F 2 , OF 2 and HF were not detected from the processing gas.
- the amount of the chemical solution consumed in the second absorption tower (10) was 0.7 kg / hr for the base KOH and 1.9 kg / hr for the reducing agent K 2 SO 3 .
- Example 2 In Example 1, except that the F 2 concentration in the exhaust gas to be treated was 40 vol%, was performed in the same manner as in Example 1. Gas component introduced into the second absorption tower is discharged (10) from the first absorption tower (2), the F 2 20,000 ppm by volume, 1,300 ppm by volume of HF, OF 2 42,000 volumes The gas contained ppm.
- Table 1 shows the concentration of each fluorine-based gas component in the processing gas discharged from the processing gas discharge pipe (15) and the amount of chemical solution (basic aqueous solution containing a reducing agent) used in the second step. From the process gas, F 2 and HF were not detected, and OF 2 was detected at 1 ppm by volume. The amount of the chemical solution consumed in the second absorption tower (10) was 6.7 kg / hr for the base KOH and 18 kg / hr for the reducing agent K 2 SO 3 .
- Example 3 In Example 1, the reducing agent in the chemical solution (basic aqueous solution containing a reducing agent) used in the second step was replaced with potassium sulfite (K 2 SO 3 ) and sodium thiosulfate (Na 2 S 2 O 3 ). The exhaust gas was treated in the same manner as in Example 1 except that the concentration was 3% by mass.
- K 2 SO 3 potassium sulfite
- Na 2 S 2 O 3 sodium thiosulfate
- Table 1 shows the concentration of each fluorine-based gas component in the processing gas discharged from the processing gas discharge pipe (15) and the amount of chemical solution (basic aqueous solution containing a reducing agent) used in the second step.
- F 2 , HF and OF 2 were not detected from the processing gas.
- the amount of the chemical solution consumed in the second absorption tower (10) was 0.7 kg / hr for the base KOH and 1.9 kg / hr for the Na 2 S 2 O 3 reducing agent.
- Example 4 In Example 1, the reducing agent in the chemical solution (basic aqueous solution containing a reducing agent) used in the second step was replaced by potassium iodide (KI) instead of potassium sulfite (K 2 SO 3 ), and the concentration was 3 Exhaust gas was treated in the same manner as in Example 1 except that the mass% was used.
- KI potassium iodide
- K 2 SO 3 potassium sulfite
- Table 1 shows the concentration of each fluorine-based gas component in the processing gas discharged from the processing gas discharge pipe (15) and the amount of chemical solution (basic aqueous solution containing a reducing agent) used in the second step. F 2 , HF and OF 2 were not detected from the processing gas. The amount of the chemical solution consumed in the second absorption tower (10) was 0.7 kg / hr for the base KOH and 2.0 kg / hr for the reducing agent KI.
- Example 5 In Example 1, the reducing agent in the chemical solution (basic aqueous solution containing the reducing agent) used in the second step was replaced with potassium sulfite (K 2 SO 3 ) and potassium chloride (KCl), and the concentration was 10 mass. % Exhaust gas treatment was performed in the same manner as in Example 1 except that the percentage was changed to%.
- Table 1 shows the concentration of each fluorine-based gas component in the processing gas discharged from the processing gas discharge pipe (15) and the amount of chemical solution (basic aqueous solution containing a reducing agent) used in the second step. From the process gas, F 2 and HF were not detected, and OF 2 was detected at 0.3 volume ppm. The amount of the chemical solution consumed in the second absorption tower (10) was 0.7 kg / hr for the base KOH and 1.8 kg / hr for the reducing agent KCl.
- Example 1 A device similar to the device used in the first step of Example 1 and provided with the first absorption tower (2) and the circulating fluid tank 1 (6) was used to circulate water in the same manner as in Example 1 to circulate the circulating fluid. The introduction amount of water and the drainage amount of the circulating fluid were adjusted so that the HF concentration in the tank 1 (6) was 1% by mass. Exhaust gas similar to that in Example 1 was introduced from the exhaust gas introduction pipe 1 (1) and treated, and the gas component discharged from the top of the first absorption tower (2) was used as the treatment gas. As shown in Table 1, the concentration of each fluorine-based gas component in the treatment gas was 980 ppm by volume for F 2 , 670 ppm by volume for HF, and 4,050 ppm by volume for OF 2 .
- Example 2 In Example 1, the first step is bypassed, and the exhaust gas to be treated is introduced from the exhaust gas introduction pipe 2 (9) into the second absorption tower (10), and the exhaust gas is treated in the same manner as in the second step of Example 1. went.
- Table 1 shows the concentration of each fluorine-based gas component in the processing gas discharged from the processing gas discharge pipe (15) and the amount of chemical solution (basic aqueous solution containing a reducing agent).
- F 2 , HF and OF 2 were not detected from the processing gas, but the amount of chemical consumed in the second absorption tower (10) was 53 kg / hr for the base KOH and K 2 SO 3 for the reducing agent. It was 127 kg / hr, and the amount of chemical used was larger than that in Example 1.
- the exhaust gas treatment method of the present invention treats an exhaust gas containing elemental fluorine generated in a process using a fluorine-based gas or a process for producing a fluorine-based gas as an etching or cleaning gas, thereby substantially treating the fluorine-based gas. It is suitable as a method for obtaining a processing gas not contained in the above.
- Exhaust gas introduction pipe 1 2 First absorption tower 3: Packed bed 1 4: Water supply pipe 5: HF aqueous solution discharge pipe 6: Circulating fluid tank 1 7: Circulation pump 1 8: shower nozzle 1 9: Exhaust gas introduction pipe 2 10: Second absorption tower 11: Packed bed 2 12: Circulating fluid tank 2 13: Circulation pump 2 14: shower nozzle 2 15: Process gas discharge pipe
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Abstract
Description
〔1〕フッ素元素を含有する排ガスと、水とを接触させる第一工程と、第一工程から排出されたガス成分を、還元剤を含む塩基性水溶液と接触させる第二工程とを有することを特徴とするフッ素元素を含有する排ガスの処理方法。
〔2〕前記フッ素元素を含有する排ガスが、フッ素ガス(F2)および/またはフッ化水素(HF)を含有することを特徴とする前記〔1〕に記載のフッ素元素を含有する排ガスの処理方法。
〔3〕前記還元剤が、硫黄系還元剤であることを特徴とする前記〔1〕または〔2〕に記載のフッ素元素を含有する排ガスの処理方法。
〔4〕前記硫黄系還元剤が、亜硫酸塩および/またはチオ硫酸塩であることを特徴とする前記〔3〕に記載のフッ素元素を含有する排ガスの処理方法。
〔5〕前記第一工程において、水と接触させる際の排ガス中のフッ素ガス濃度が、40体積%以下であることを特徴とする前記〔1〕~〔4〕のいずれかに記載のフッ素元素を含有する排ガスの処理方法。
〔6〕前記第一工程から排出されたガス成分中の二フッ化酸素(OF2)濃度が、5体積%以下であることを特徴とする前記〔1〕~〔5〕のいずれかに記載のフッ素元素を含有する排ガスの処理方法。
〔7〕前記第二工程から排出されたガス成分中の二フッ化酸素(OF2)濃度が、1体積ppm以下であることを特徴とする前記〔1〕~〔6〕のいずれかに記載のフッ素元素を含有する排ガスの処理方法。
第一工程では、フッ素元素を含有する排ガスと、水とを接触させる。
フッ素ガスと水との接触では、フッ素ガスの反応性が高いことから、前記反応式(1)の主反応の他に、条件によってはオゾン(O3)や二フッ化酸素(OF2)を生成する副反応が生じることが知られている。しかしながら本発明者は、水と接触させる際の排ガス中のフッ素ガス濃度を40体積%以下とした場合には、副反応が抑制され、オゾン(O3)はほとんど生成せず、二フッ化酸素(OF2)の生成も低く抑えられることを見出した。
第二工程では、第一工程から排出されたガス成分を、還元剤を含む塩基性水溶液と接触させる。
以下の実施例および比較例において、各フッ素系ガス成分の濃度は次のようにして測定し、定量した。
充填層1(3)に充填物としてカスケードミニリングを充填高さ4mで充填した直径500mmの第1吸収塔(2)と、充填層2(11)に充填物としてカスケードミニリングを充填高さ4mで充填した直径500mmの第2吸収塔(10)とを備えた装置を用いて排ガスの処理を行った。図1に概略図を示す。
実施例1において、処理する排ガス中のF2濃度を40体積%としたこと以外は、実施例1と同様に行った。第1吸収塔(2)から排出されて第2吸収塔(10)に導入されるガス成分は、F2を20,000体積ppm、HFを1,300体積ppm、OF2を42,000体積ppm含むガスであった。
実施例1において、第二工程で用いた薬液(還元剤を含む塩基性水溶液)中の還元剤を、亜硫酸カリウム(K2SO3)に代えてチオ硫酸ナトリウム(Na2S2O3)とし、その濃度を3質量%としたことの他は、実施例1と同様にして排ガスの処理を行った。
実施例1において、第二工程で用いた薬液(還元剤を含む塩基性水溶液)中の還元剤を、亜硫酸カリウム(K2SO3)に代えてヨウ化カリウム(KI)とし、その濃度を3質量%としたことの他は、実施例1と同様にして排ガスの処理を行った。
実施例1において、第二工程で用いた薬液(還元剤を含む塩基性水溶液)中の還元剤を、亜硫酸カリウム(K2SO3)に代えて塩化カリウム(KCl)とし、その濃度を10質量%としたことの他は、実施例1と同様にして排ガスの処理を行った。
第1吸収塔(2)および循環液タンク1(6)を備えた、実施例1の第一工程で用いた装置と同様の装置を用い、実施例1と同様に水を循環させ、循環液タンク1(6)内のHF濃度が1質量%となるように水の導入量および循環液の排液量を調整した。実施例1と同様の排ガスを排ガス導入管1(1)より導入して処理し、第1吸収塔(2)の塔頂から排出されるガス成分を処理ガスとした。処理ガス中の各フッ素系ガス成分の濃度は、表1に示すとおり、F2が980体積ppm、HFが670体積ppm、OF2が4,050体積ppmであった。
実施例1において、第一工程をバイパスし、処理する排ガスを排ガス導入管2(9)から第2吸収塔(10)に導入し、実施例1の第二工程と同様にして排ガスの処理を行った。
2:第1吸収塔
3:充填層1
4:給水管
5:HF水溶液排出管
6:循環液タンク1
7:循環ポンプ1
8:シャワーノズル1
9:排ガス導入管2
10:第2吸収塔
11:充填層2
12:循環液タンク2
13:循環ポンプ2
14:シャワーノズル2
15:処理ガス排出管
Claims (7)
- フッ素元素を含有する排ガスと、水とを接触させる第一工程と、
第一工程から排出されたガス成分を、還元剤を含む塩基性水溶液と接触させる第二工程とを有することを特徴とするフッ素元素を含有する排ガスの処理方法。 - 前記フッ素元素を含有する排ガスが、フッ素ガスおよび/またはフッ化水素を含有することを特徴とする請求項1に記載のフッ素元素を含有する排ガスの処理方法。
- 前記還元剤が、硫黄系還元剤であることを特徴とする請求項1または2に記載のフッ素元素を含有する排ガスの処理方法。
- 前記硫黄系還元剤が、亜硫酸塩および/またはチオ硫酸塩であることを特徴とする請求項3に記載のフッ素元素を含有する排ガスの処理方法。
- 前記第一工程において、水と接触させる際の排ガス中のフッ素ガス濃度が、40体積%以下であることを特徴とする請求項1~4のいずれかに記載のフッ素元素を含有する排ガスの処理方法。
- 前記第一工程から排出されたガス成分中の二フッ化酸素濃度が、5体積%以下であることを特徴とする請求項1~5のいずれかに記載のフッ素元素を含有する排ガスの処理方法。
- 前記第二工程から排出されたガス成分中の二フッ化酸素濃度が、1体積ppm以下であることを特徴とする請求項1~6のいずれかに記載のフッ素元素を含有する排ガスの処理方法。
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EP3384975A4 (en) | 2019-08-07 |
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