JP2008279330A - Treating method and treatment apparatus of exhaust gas containing perfruoride - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treating method and a treatment apparatus of perfruoride decomposition gas with little drain, for efficiently removing high concentration HF gas by using a Ca salt, recovering CaF<SB>2</SB>of a high purity. <P>SOLUTION: Exhaust gas containing perfluoride discharged from a semiconductor manufacturing apparatus, a liquid crystal manufacturing apparatus, or a solar cell manufacturing apparatus is decomposed in a perfluoride decomposition apparatus 1, high concentration HF gas formed by decomposition is removed in first and second acidic gas removing apparatus 2, 3. The Ca salt is used for HF gas, low concentration HF gas is reacted with the Ca salt in the second acidic gas removing apparatus 3, the Ca salt containing low purity CaF<SB>2</SB>produced in the reaction is fed to the first acidic gas removing apparatus 2, and is reacted with the highly concentrated HF to obtain high purity CaF<SB>2</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and apparatus for treating exhaust gas containing perfluoride discharged without being used or a reaction product produced by decomposition of perfluoride, and more particularly to a semiconductor manufacturing apparatus or liquid crystal manufacturing apparatus, solar Exhaust gas treatment method including perfluoride suitable for efficiently removing perfluoride discharged from battery manufacturing equipment and acid gas components in exhaust gas including reaction products generated by decomposition of perfluoride and its The present invention relates to a processing apparatus.

Perfluoro compounds are CF ₄ , CHF ₃ , C ₂ F ₆ , CH ₂ F ₂ , C ₃ F ₈ ,
A generic term for compounds of carbon and fluorine, carbon and hydrogen and fluorine, sulfur and fluorine, and nitrogen and fluorine, such as C ₅ F ₈ , SF ₆ and NF ₃ . Perfluoride (referred to as PFC) is used as an etching gas, a cleaning gas, and an ashing gas in a semiconductor manufacturing process, a liquid crystal manufacturing process, or a solar cell manufacturing process. Perfluoride is stable in the atmosphere for a long period of time, and has the property of absorbing thousands of times the infrared rays of carbon dioxide. Therefore, it is designated as a regulated gas in the Kyoto Protocol, and it is required to reduce the amount released to the atmosphere.

  In order to reduce the perfluoride emission to the atmosphere, various detoxification methods have been studied. There are a catalytic method using a catalyst, a plasma method using plasma, and a combustion method in which combustion is performed in a high-temperature combustion gas. However, in any of these treatment methods, hydrogen fluoride (HF), which is a highly corrosive gas, is generated after the decomposition of perfluoride. As for the treatment of hydrogen fluoride gas when the concentration of hydrogen fluoride is high, a removal method by wet cleaning is mainly used.

  Removal by wet cleaning has the advantage of simultaneously cooling the high-temperature gas and removing the generated high-concentration hydrogen fluoride gas, but on the other hand, wet cleaning produces a large amount of acidic wastewater, so it is acidic. Wastewater treatment equipment is required.

  In order to discharge wastewater containing fluorine into rivers and the sea, the fluorine concentration must be below the legal regulation value, and the fluorine in the wastewater must be separated and removed almost 100%. As the amount of wastewater to be treated increases and the concentration of fluorine contained in the wastewater increases, the wastewater treatment facility for treating the fluorine concentration in the wastewater to be below the legal regulation value becomes larger.

  In order to almost completely remove fluorine from wastewater using calcium hydroxide, calcium hydroxide several times the theoretical reaction amount must be added. At that time, calcium fluoride produced by reacting with fluorine in waste water and excessively added calcium hydroxide contain excessive moisture, and therefore cannot be reused, resulting in industrial waste.

  As a method for treating perfluoride from an etcher using a catalyst in a semiconductor manufacturing process or a liquid crystal manufacturing process in order to suppress the release of perfluoride to the atmosphere, a method described in [Patent Document 1] is known. As a method for removing HF gas generated by PFC decomposition with a Ca salt, a method described in [Patent Document 2] is known.

Japanese Patent No. 3237651 JP 2003-340239 A

  Perfluoride is a stable gas and must be burned at a high temperature of about 1200 ° C. or higher to be decomposed by a combustion method. Moreover, when decomposing | disassembling by a catalyst system, it is necessary to heat to about 700 degreeC. In addition, perfluoride has a plurality of fluorine atoms, and the concentration of hydrogen fluoride produced after decomposition is several times the concentration of perfluoride supplied to the cracking unit. It becomes a gas containing acidic gas (HF) with high concentration at high temperature.

  In order to cool this exhaust gas and remove acidic gas, water is generally used because of its large specific heat and large latent heat of vaporization. However, the higher the decomposition temperature of the gas to be treated, the more water is required.

  Semiconductor manufacturing plants and liquid crystal manufacturing plants consume a large amount of water in the cleaning process and the like, and the amount of wastewater treated is also increasing. Recently, semiconductor manufacturing factories and liquid crystal manufacturing factories are working to reduce the amount of waste from the factories, and reducing the amount of wastewater generated has become a major issue. In particular, in semiconductor manufacturing plants and liquid crystal manufacturing factories, since there are many processes in which wastewater containing fluorine is generated, it is necessary to reduce the amount of wastewater containing fluorine.

  At existing semiconductor and liquid crystal manufacturing plants, PFC gas is prevented from being released to the atmosphere in the future, so when a perfluoride decomposition device is introduced into the entire PFC-using manufacturing process, it is generated by decomposition of PFC gas. When all high-concentration acid gases are treated by a wet cleaning method, there is a problem that the treatment of wastewater containing fluorine approaches a limit.

In general, when high concentration HF gas is removed by contact with Ca salt in a dry process, the reaction efficiency with Ca salt is low, and therefore low purity CaF ₂ containing 50% or more of unused Ca salt. Is discharged as a reaction product.

If the purity of CaF ₂ is low, it is difficult to recycle it into PFC gas raw material or fluororesin raw material, and there is a problem that the use value is low, such as having the cement factory collect it for a fee as a waste, and the utility value is low. is there. Therefore, if the generation amount increases in the future, there will be no take-up destination, and eventually landfill processing will be performed, resulting in an increase in processing cost and a new problem.

  The object of the present invention is to reduce the amount of water used when treating exhaust gas containing high-concentration hydrogen fluoride gas produced by the decomposition of perfluoride, to efficiently react Ca salt and hydrogen fluoride, and to achieve high purity. It is an object to provide an exhaust gas treatment method and apparatus for a perfluoride decomposition apparatus for obtaining calcium fluoride.

  In order to achieve the above object, the present invention removes the acid gas contained in the exhaust gas generated by the decomposition treatment of perfluoride by reacting with Ca salt, and makes contact with Ca salt in two stages. This is done separately.

  Further, the process of removing the high concentration hydrogen fluoride gas generated by the decomposition of perfluoride is made into two stages, and in the first stage removal process, the high concentration hydrogen fluoride gas and Ca salt are reacted, In the removing step, low concentration hydrogen fluoride gas and Ca salt are reacted.

In addition, a new Ca salt is supplied in the second stage removal process, and in the second stage removal process, a low concentration HF gas discharged from the first stage is processed, and a Ca salt containing low purity CaF ₂ is obtained. The Ca salt containing low-purity CaF ₂ generated in the second-stage removal step is partially or entirely supplied intermittently or continuously to the first-stage removal step. A high-concentration HF gas is removed using a Ca salt containing pure CaF ₂ .

  According to the present invention, since the treatment using a dry method using Ca salt is performed to remove the acidic gas contained in the exhaust gas, the amount of waste water can be reduced as compared with conventional moisture cleaning. In addition, the reaction between the high-concentration hydrogen fluoride contained in the exhaust gas and the Ca salt can be efficiently performed, and the produced calcium fluoride can be obtained with a high purity, and the utility value of calcium fluoride can be increased. is there.

  Each embodiment will be described with reference to the drawings.

  A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. The structure of the perfluoride decomposition apparatus 1 using a catalyst is shown in FIG. The perfluoride decomposition apparatus 1 can be applied to a combustion method or a plasma method in addition to a catalyst method.

  Exhaust gas containing perfluoride discharged from an etching apparatus, ashing apparatus, or CVD apparatus (not shown) is supplied to the perfluoride decomposition apparatus 1.

  As shown in FIG. 8, the perfluoride decomposition apparatus 1 is connected to a first heating device 11 into which exhaust gas and water are introduced, a heater 14 installed outside the first heating device 11, and the first heating device 11. The second heating device 12, the heater 15 installed outside the second heating device 12, and the catalyst 13 provided in the subsequent stage of the second heating device. When the amount of the processing gas is small, the first heating device 11 can be heated up to the temperature until the decomposition reaction, and the second heating device 12 may be omitted.

  The first heating device 11 is supplied with exhaust gas containing perfluoride and is heated from 300 ° C. to 500 ° C. by the heater 14. The first heating device 11 is supplied with water or steam necessary for the perfluoride decomposition reaction at the catalyst 13 and is mixed with the exhaust gas containing the perfluoride.

  The exhaust gas containing perfluoride to which water or steam is added is heated from 500 to 750 ° C. by the heater 15 in the second heating device 12. Exhaust gas containing perfluoride heated to 500 to 750 ° C. is supplied to the catalyst 13, where the perfluoride and water react to decompose the perfluoride. An example of the perfluoride decomposition reaction formula is shown in Equation 1.

  The catalyst 13 may be structured such that a removable container can be filled and the entire container can be taken out so that the catalyst can be easily replaced.

The cracked gas produced by the cracking reaction at the catalyst 13 contains a high concentration of HF gas. In the reaction formula shown in Formula 1, when the exhaust gas containing CF ₄ 1 vol%, since four times the HF of CF ₄ is produced by the decomposition reaction, the decomposition gas, contains 4 vol% as high a concentration of HF Discharged.

  The cracked gas containing high-concentration HF is supplied to the first acid gas removal device 2 connected to the perfluoride cracking device 1. Even if the cracked gas contains an acid gas such as SOx or NOx other than HF, the treatment is possible.

As shown in FIG. 2, the first acid gas removal device 2 reacts with the Ca salt from the pipe 26 that supplies Ca salt from the second acid gas removal device 3 to the first acid gas removal device 2. A first acid gas reaction unit 21 to be reacted, a first discharge device 22 for discharging Ca salt containing CaF ₂ produced by reacting with high concentration HF with high purity, and a Ca salt containing CaF ₂ discharged with high purity. The first storage tank 23 for storage and the first transfer device 24 for discharging Ca salt containing CaF ₂ with high purity from the first storage tank 23 are configured. Here, as a Ca salt, can be used _{Ca (OH) 2, CaCO 3} , CaO.

In the first acid gas removal device 2, Ca salt containing CaF ₂ discharged from the second acid gas removal device 3 at a low purity upstream of the first acid gas reaction unit 21 is supplied through the pipe 26, and has a high concentration of HF. In the first acidic gas reaction unit 21, the high-concentration HF gas reacts with a Ca salt containing low-purity CaF ₂ to increase the purity of CaF ₂ to 60 to 80%. . Since the removal rate of high-concentration HF in the first acidic gas reaction unit 21 is about 90 to 95%, 4 vol% of HF gas is converted from the first acidic gas removal device 2 as low-concentration HF gas of 2000 to 4000 ppm. Discharged.

In the first acidic gas reaction unit 21, a Ca salt containing CaF ₂ with high purity is collected by the filter 25. Ca salt containing CaF ₂ collected by the filter 25 with high purity is dropped from the downstream of the filter 25 to the lower part of the first acidic gas reaction section 21 by jetting compressed air to the filter 25 and performing backwashing. be able to. A first discharge device 22 is installed below the first acidic gas reaction unit 21, and Ca salt containing CaF ₂ with high purity is discharged to the first storage tank 23 by the first discharge device 22. The Ca salt containing CaF ₂ stored in the first storage tank 23 with high purity is discharged out of the system by the first transfer device 24.

  The cracked gas containing the low-concentration HF gas discharged from the first acid gas removal device 2 is supplied to the second acid gas removal device 3 connected to the first acid gas removal device 2. A pipe 41 for supplying Ca salt from the Ca salt supply device 4 is provided on the upstream side of the second acid gas removal device 3, and the Ca salt is mixed with cracked gas containing low-concentration HF gas, The diacid gas removal device 3 is supplied.

As shown in FIG. 2, the second acidic gas removal device 3 includes a second acidic gas reaction unit 31 that reacts Ca salt with low-concentration HF, and CaF ₂ that is generated by reacting with low-concentration HF with low purity. second discharge device for discharging the Ca salt 32, to discharge the Ca salt containing CaF ₂ discharged second storage tank 33 for storing a Ca salt comprising at low purity, the CaF ₂ from the second storage tank 33 at a low purity The second transfer device 34 is configured.

In the second acid gas removing device 3, Ca salt and cracked gas containing low concentration HF are mixed, and low concentration HF and Ca salt react in the second acid gas reaction section, and CaF ₂ is 20 to 40%. Contains Ca salt.

Since the removal rate of the low concentration HF in the second acidic gas reaction unit 31 is 99% or more, 2000 to 2000
The HF gas having a low concentration of 4000 ppm can react with the Ca salt to make the HF concentration below the emission regulation value to the atmosphere.

  The exhaust gas from which the HF gas has been removed by the second acid gas reaction unit 31 is sent to the exhaust gas treatment facility (not shown) of the semiconductor manufacturing plant, liquid crystal manufacturing plant, or solar cell manufacturing plant via the suction device 5. Discharged.

In the second acidic gas reaction unit 31, the Ca salt containing CaF ₂ with low purity is collected by the filter 35. The Ca salt containing low-purity CaF ₂ collected by the filter 35 is dropped from the downstream of the filter 35 to the lower part of the second acid gas reaction unit 31 by jetting compressed air onto the filter 35 and backwashing. be able to.

A second discharge device 32 is installed below the second acid gas reaction unit 31, and Ca salt containing CaF ₂ with low purity is discharged to the second storage tank 33 by the second discharge device 32.

The Ca salt containing CaF ₂ stored in the second storage tank 33 with low purity is supplied to the first acid gas removal device 2 by the second transfer device 34.

  In order to remove the low concentration hydrogen fluoride gas in the exhaust gas by reacting with the Ca salt, it is necessary to increase the purity of the Ca salt and the contact area of the Ca surface in order to improve the contact efficiency with HF. is there. It is also important to increase the amount of Ca salt to increase the contact time with the exhaust gas. On the other hand, when removing high-concentration hydrogen fluoride gas, even if the Ca salt contains impurities, the contact with HF increases, so that it can be reacted easily.

  However, when removing high-concentration HF gas using Ca salt, the removal rate can only be about 90 to 99 in the one-stage removal process. Become.

  For this reason, in order to reduce the consumption of the Ca salt and increase the calcium fluoride purity in the Ca salt, the high-concentration HF gas is treated in the first-stage removal process by the two-stage removal process. The low concentration HF gas is processed in the removing step. At this time, the Ca salt containing low-purity calcium fluoride produced in the second-stage removal step is supplied to the first-stage removal step and used for removing the high-concentration HF gas produced by the decomposition of perfluoride. Can recover a high concentration of calcium fluoride.

According to this embodiment, the process of removing the high concentration hydrogen fluoride gas generated by the decomposition of perfluoride is made into two stages, and in the first stage of removal process, the high concentration hydrogen fluoride gas and Ca salt are reacted. In the second removal step, since the low concentration hydrogen fluoride gas and Ca salt are reacted, the contact efficiency between the high concentration HF gas and the Ca salt can be increased, and high purity CaF ₂ can be obtained. .

In addition, a new Ca salt is supplied in the second stage removal process, and in the second stage removal process, a low concentration HF gas discharged from the first stage is processed, and a Ca salt containing low purity CaF ₂ is obtained. The Ca salt containing low-purity CaF ₂ generated in the second-stage removal step is partially or entirely supplied intermittently or continuously to the first-stage removal step. By removing a high concentration of HF gas using a Ca salt containing pure CaF ₂ , a Ca salt containing high purity CaF ₂ can be recovered.

  An exhaust gas treatment system for perfluoride decomposition treatment that is Embodiment 2 of the present invention will be described with reference to FIG. FIG. 3 shows an example in which the first acidic gas removing device 2 and the second acidic gas removing device 3 are HF gas removed by a Ca salt fixed layer.

A Ca salt containing low-purity CaF ₂ is continuously or intermittently supplied from the second transfer device 34 to the upper portion of the first acidic gas removal device 2. The cracked gas containing high-concentration HF discharged from the perfluoride cracking apparatus 1 is supplied to the lower part of the first acid gas reaction unit 21 of the first acid gas removing apparatus 2 and is a fixed layer of Ca salt containing low-purity CaF _2. By passing through the inside, the high-concentration HF gas in the cracked gas reacts with the Ca salt. By reacting with the Ca salt, the high-concentration HF gas becomes a low-concentration HF gas, is discharged from the upper part of the first acidic gas reaction unit 21, and is supplied to the second acidic gas removal device 3.

In the first acidic gas removal apparatus 2, the first acidic gas reaction unit 21 is provided with a Ca salt containing high-purity CaF ₂ formed by a reaction between a high concentration of HF gas and a Ca salt. Then, a constant amount is discharged continuously or intermittently to the first storage tank 23.

  In the second acid gas removing device 3, the Ca salt is continuously or intermittently supplied from the Ca salt supply device 4 to the upper part of the second acid gas reaction unit 31. The cracked gas containing low-concentration HF discharged from the first acid gas removal device 2 is supplied to the lower part of the second acid gas reaction unit 31 and passes through the Ca salt fixed layer, so that the cracked gas in the cracked gas is contained. A low concentration of HF gas reacts with Ca salt. The low-concentration HF gas is removed by reacting with the Ca salt, and is discharged from the upper part of the second acidic gas reaction unit 31.

In the second acid gas removal device 3, a Ca salt containing low-purity CaF ₂ produced by the reaction of a low-concentration HF gas and a Ca salt is used in the second discharge device 32 provided in the second acid gas reaction unit 31. A constant amount is discharged to the second storage tank 33 continuously or intermittently. The Ca salt containing low-purity CaF ₂ discharged to the second storage tank 33 is continuously or intermittently supplied to the first acidic gas removal device 2 by the second transfer device 34.

  In addition, the 1st acidic gas reaction part and the 2nd acidic gas reaction part may combine the filter system shown in FIG. 2, and the fixed layer shown in FIG. 3, and can acquire the same effect.

  According to this example, there is an effect similar to that of Example 1, and sufficient contact can be made by passing through the Ca salt fixed layer.

A perfluoride decomposition treatment exhaust gas treatment system that is Embodiment 3 of the present invention will be described with reference to FIG. FIG. 4 shows an example in which a Ca salt containing low-purity CaF ₂ is supplied continuously or intermittently to the first acidic gas removal device 2 without using the second storage tank 33 and the second transfer device 34. In the present embodiment, the second acidic gas removal device 3 is disposed above the first acidic gas removal device 2. In the 2nd acid gas removal apparatus 3, the 2nd discharge device 32 provided in the 2nd acid gas reaction part 31 and the 2nd acid gas reaction part 31 is provided, and the 2nd discharge device 32 is the 1st acid gas removal. It is connected to the upper part of the first acidic gas reaction part 21 in the apparatus 2.

The cracked gas containing the low-concentration HF gas supplied to the second acidic gas removal device 3 reacts with the Ca salt in the second acidic gas reaction unit 31 to generate a Ca salt containing low-purity CaF ₂ . By opening the second discharge device 32 at the lower part of the second acidic gas reaction unit 31, it is possible to supply Ca salt containing low-purity CaF ₂ to the first acidic gas removal device 2 by using gravity.

  According to the present embodiment, there are the same effects as in the first embodiment, the second storage tank 33 and the second transfer device 34 of the second acidic gas removal device 3 can be omitted, and the system can be simplified.

  An exhaust gas treatment system for perfluoride decomposition treatment that is Embodiment 4 of the present invention will be described with reference to FIGS. When the temperature at which perfluoride is decomposed by the perfluoride decomposition apparatus 1 is high, the decomposition gas is discharged at a high temperature. In order to efficiently perform the reaction between the Ca salt and the high-concentration HF gas in the first acid gas removal device 2, a cooling device 6 is provided between the perfluoride decomposition device 1 and the first acid gas removal device 2. Yes.

  FIG. 5 shows a cooling device 6 that performs heat exchange with air as an example of efficiently lowering the cracked gas temperature. External air is taken in by the blower 65 and supplied to the cooling unit 64. The amount of air supplied to the blower 65 is variable by measuring the cracked gas temperature at the outlet of the cooling unit 64 and changing the rotational speed of the blower by inverter control or the like based on the measured cracked gas temperature.

  The cooling unit 64 is provided with fins in order to improve heat exchange between the high-temperature cracked gas and air, so that the high-temperature cracked gas efficiently reacts with Ca salt and high-concentration HF gas. The temperature can be lowered to the required temperature.

  In FIG. 6, as an example of efficiently reducing the cracked gas temperature, a cooling device 6 that performs heat exchange with water is shown. Cooling water is supplied from the cooling tower 61 to the cooling unit 64 by the pump 62. The cooling unit 64 is provided with a coil 63 through which cooling water flows in order to exchange heat with the high-temperature cracked gas. As the cooling water flows through the coil 63, the high-temperature cracked gas can be lowered to a temperature at which the reaction between the Ca salt and the high-concentration HF gas is efficiently performed.

  A perfluoride decomposition treatment exhaust gas treatment system that is Embodiment 5 of the present invention will be described with reference to FIG.

  FIG. 7 shows a perfluoride decomposition processing system for large-scale processing for processing perfluoride in the entire semiconductor manufacturing plant or liquid crystal manufacturing plant. In FIG. 7, the processing in three perfluoride decomposing apparatuses is illustrated, but the present invention can be similarly applied to the processing in more perfluorinated decomposing apparatuses.

The cracked gas containing high-concentration HF gas discharged from the perfluoride decomposing apparatuses 1a, 1b, 1c is converted into first acid gas removing apparatuses 2a, 2a, 2c connected to the first perfluoride decomposing apparatuses 1a, 1b, 1c.
2b and 2c. A Ca salt containing low-purity CaF ₂ is continuously or intermittently supplied from one second acidic gas removing device 3 to each acidic gas removing device 2a, 2b, 2c.

In each first acidic gas removal device 2a, 2b, 2c, a Ca salt containing high-concentration HF and low-purity CaF ₂ reacts to produce a Ca salt containing high-purity CaF ₂ . The cracked gas containing low-concentration HF discharged from each first acid gas removal device 2a, 2b, 2c is supplied to one second acid gas removal device 3. The second acidic gas removal device 3 is supplied with Ca salt from the Ca salt supply device 4 to remove low-concentration HF.

A Ca salt containing low-purity CaF ₂ produced by reacting with a low concentration of HF and Ca salt is supplied to each of the first acidic gas removal devices 2a, 2b, and 2c. This makes it possible to remove high-concentration HF from a plurality of perfluoride decomposition apparatuses with a small equipment configuration.

  An exhaust gas treatment system for decomposition of perfluoride which is Embodiment 6 of the present invention will be described with reference to FIG. FIG. 9 shows an example in which a third acidic gas removal device 9 is provided upstream of the perfluoride decomposition device 1.

  An exhaust gas containing perfluoride discharged from an etching apparatus, an ashing apparatus, or a CVD apparatus (not shown) may contain powder, acid, or the like. When these components are contained, clogging inside the perfluoride decomposition apparatus 1 and corrosion due to acid gas occur. To prevent this, the third acid gas removal apparatus 9 is disposed upstream of the perfluoride decomposition apparatus 1. Is provided.

The exhaust gas containing the powder or the substance that generates the powder and the acid gas is supplied to the third acid gas removing device 9. A part or all of the Ca salt containing high-purity CaF ₂ from the first acid gas removal device 2 is supplied to the third acid gas removal device 9 continuously or intermittently. In the third acidic gas removing device 9, the perfluoride decomposition device is removed by removing the gas or the substance that generates the powder and the gas containing the acidic gas by reacting or adsorbing with the Ca salt containing high-purity CaF _2. It is possible to prevent clogging inside 1 and corrosion by acid gas. The 3rd acidic gas removal apparatus 9 can be comprised by the filter system of the same apparatus structure as the 1st acidic gas removal apparatus 2 shown in FIG. 2, FIG. 3, and a fixed layer system.

1 is a configuration diagram of an exhaust gas treatment system for perfluoride decomposition that is Embodiment 1 of the present invention. FIG. The longitudinal cross-sectional view which shows the acidic gas removal apparatus using a filter. The block diagram of the exhaust gas processing system of the perfluoride decomposition | disassembly which is Example 2 of this invention. The block diagram of the waste gas processing system of the perfluoride decomposition | disassembly which is Example 3 of this invention. The block diagram of the waste gas processing system of the perfluoride decomposition | disassembly which is Example 4 of this invention. The block diagram of the waste gas treatment system of the perfluoride decomposition | disassembly which shows the example which provided the cooling device of water cooling. The block diagram of the waste gas processing system of the perfluoride decomposition | disassembly which is Example 5 of this invention. The block diagram of the perfluoride decomposition | disassembly apparatus using a catalyst. The block diagram of the waste gas treatment system of perfluoride decomposition which is Example 6 of this invention.

Explanation of symbols

1, 1a, 1b, 1c Perfluoride decomposing device 2, 2a, 2b, 2c First acid gas removing device 3 Second acid gas removing device 4 Ca salt supply device 5 Suction device 6 Cooling device 11 First heating device 12 Second heating device 13 Catalyst 14, 15 Heater 21 First acid gas reaction unit 22 First discharge device 23 First storage tank 24 First transfer device 25, 35 Filter 26, 41 Pipe 31 Second acid gas reaction unit 32 Second discharge Device 33 Second storage tank 34 Second transfer device 61 Cooling tower 62 Pump 63 Cooling coil 64 Cooling unit 65 Blower

Claims (12)

  A method for exhaust gas treatment of perfluoride, which removes acid gas contained in exhaust gas generated by the decomposition treatment of perfluoride by reacting with Ca salt and performing contact with Ca salt in two stages.   The process of removing the high concentration hydrogen fluoride gas generated by the decomposition of perfluoride is made into two stages, and the first stage of the removal process is the reaction of the high concentration hydrogen fluoride gas and Ca salt to the second stage of removal process. Then, an exhaust gas treatment method for perfluoride, in which low concentration hydrogen fluoride gas and Ca salt are reacted. The new Ca salt is supplied in the second stage removal process, and in the second stage removal process, the low concentration HF gas discharged from the first stage is processed to produce a Ca salt containing low purity CaF _2. The Ca salt containing low-purity CaF ₂ generated in the second-stage removal process is partially or entirely supplied intermittently or continuously to the first-stage removal process. An exhaust gas treatment method for perfluoride in which high-concentration HF gas is removed using a Ca salt containing CaF ₂ .   Two-stage contact between the acid gas and the Ca salt is performed in the first acid gas removal step and the second acid gas removal step, and part or all of the Ca salt in the second acid gas removal step is transferred to the first acid gas removal step. The perfluoride exhaust gas treatment method according to claim 1 to be supplied.   5. The perfluoride exhaust gas treatment method according to claim 1, wherein the exhaust gas generated by the decomposition treatment of perfluoride is cooled and then reacted with Ca salt.   A perfluoride decomposing apparatus for decomposing perfluoride, a first acid gas removing apparatus and a second acid gas removing apparatus for removing acid gas contained in the exhaust gas generated by the decomposition of the perfluoride. Fluoride exhaust gas treatment equipment.   The exhaust gas treatment apparatus for perfluoride according to claim 6, wherein a Ca salt supply device for supplying Ca salt to the second acid gas removal device is provided.   The perfluoride exhaust gas treatment device according to claim 6, wherein a cooling device for cooling the exhaust gas discharged from the perfluoride decomposition device is provided between the perfluoride decomposition device and the first acidic gas removal device.   The exhaust gas treatment apparatus for perfluoride according to claim 6, further comprising a Ca salt transfer device for transferring part or all of the Ca salt discharged from the second acid gas removal device to the first acid gas removal device.   A third acidic gas removal device is provided in the preceding stage of the perfluoride decomposition device, and Ca salt discharged from the first acidic gas removal device is supplied to the third acidic gas removal device to remove powder or acidic gas. The apparatus for treating exhaust gas of perfluoride according to claim 5, wherein:   Two or more perfluoride decomposing apparatuses for decomposing perfluoride, two or more first acid gas removing apparatuses and one for removing acid gas contained in the exhaust gas generated by the decomposition of perfluoride An apparatus for treating exhaust gas from perfluoride characterized by comprising the second acid gas removal apparatus.   A Ca salt supply device that supplies Ca salt to the one second acid gas removal device and a portion of Ca salt discharged from the second acid gas removal device to two or more first acid gas removal devices or 12. The perfluoride exhaust gas treatment apparatus according to claim 11, further comprising a Ca salt transfer device for transferring the whole.

Images