JP6071892B2 - Perfluoride decomposition treatment method and treatment apparatus - Google Patents

Description

  The present invention relates to a perfluoride decomposition processing method and a processing apparatus therefor, and more particularly, the perfluoride discharged from a semiconductor manufacturing apparatus, a liquid crystal manufacturing apparatus, a solar cell manufacturing apparatus, or the like is decomposed efficiently and generated by decomposition. The present invention relates to a perfluoride decomposition method suitable for removing acidic gas components contained in cracked gas and a processing apparatus therefor.

Perfluorinated compounds (perfluoro compounds, PFCs) are carbon such as CF ₄ , CHF ₃ , C ₂ F ₆ , CH ₂ F ₂ , C ₃ F ₈ , C ₄ F ₈ , C ₅ F ₈ , SF ₆ and NF _3. And fluorine, carbon and hydrogen and fluorine, sulfur and fluorine, and nitrogen and fluorine. Perfluoride is used as an etching gas, a cleaning gas, or an ashing gas in a semiconductor manufacturing process, a liquid crystal manufacturing process, or a solar cell manufacturing process.

  The perfluoride is not completely consumed during the production process, but about 10 to 50% of the supplied perfluoride is released into the atmosphere without being consumed in the production process.

  Perfluoride is a stable substance for a long time in the order of tens of thousands of years in the atmosphere, and absorbs infrared rays that are thousands to tens of thousands of times that of carbon dioxide. It is considered as one of The Kyoto Protocol for the prevention of global warming is one of the regulated gases, and there is a strong demand for reducing the amount released to the atmosphere.

  Various detoxification (decomposition) methods have been studied as a measure for suppressing perfluoride release into the atmosphere, such as a combustion method in which combustion is performed in a combustion gas, a catalyst method using a catalyst, and a plasma method using plasma.

However, since perfluoride is a stable substance that is difficult to decompose, the exhaust gas containing perfluoride needs to be heated to a high temperature. In order to obtain a high-temperature gas, in the combustion method, city gas, propane gas, methane gas or the like is directly heated as fuel, and in the catalyst method, indirect heating with an electric heater is performed. For example, when decomposing CF ₄ , the combustion method requires about 1200 ° C. or more, and the catalyst method requires about 700 to 800 ° C.

  In semiconductor manufacturing factories, liquid crystal manufacturing factories, solar cell manufacturing devices, and the like, since a large amount of energy is consumed in the whole factories, further energy saving is required. However, as described above, since perfluoride is a stable substance that is difficult to decompose, it is necessary to input a large amount of energy to decompose perfluoride. Most of the fuel and electricity used to decompose perfluoride are used to heat exhaust gas containing perfluoride.

  For this reason, the gas (decomposition gas) after decomposing | disassembling perfluoride is also discharged | emitted as high temperature gas comparable to decomposition temperature.

On the other hand, perfluoride has a plurality of fluorine atoms, and in any of the above processing methods, hydrogen fluoride generated after decomposition has a concentration several times higher than the concentration of the supplied perfluoride. For example, in the case of CF ₄ , _four fluorine atoms are formed for one carbon, so that hydrogen fluoride four times as much as the supplied CF ₄ is generated after the decomposition treatment. As a result, the decomposition gas after the decomposition treatment becomes a gas containing a high-temperature and high-concentration acidic gas (HF gas).

  Water is generally used to cool the cracked gas and remove acid gases. This is because water has a large specific heat and a large latent heat of vaporization, and hydrogen fluoride is easily dissolved in water. When hydrogen fluoride has a high concentration, a removal method by wet cleaning with a scrubber or the like is the mainstream. In the wet cleaning, the generated high-concentration hydrogen fluoride gas can be removed and the high-temperature gas can be simultaneously cooled.

  In this case, most of the energy input for heating is transferred to wastewater containing hydrofluoric acid after wet cleaning. However, the temperature of the wastewater discharged from the wet cleaning is about 40 to 60 ° C., the utility value as heat is low, and since it contains corrosive hydrofluoric acid, there is a problem that heat recovery is difficult. For this reason, there exists a problem in which the input energy is not effectively used in the wet cleaning.

  Patent Documents 1 to 3 disclose a method of treating exhaust gas containing perfluoride discharged from a semiconductor manufacturing process and a liquid crystal manufacturing process using a catalyst in order to suppress release of perfluoride to the atmosphere. . In Patent Document 1, the heat recovery rate is increased by heat-exchanging the high-temperature cracked gas after decomposition with a catalyst and water for reaction to preheat the water, and the cooled cracked gas after the heat exchanger is further increased. A method of cooling with spray water is described.

  Patent Document 2 describes a method (dry treatment) in which acidic drainage containing fluorine is not generated by adding calcium salt (hereinafter referred to as “Ca salt”) to an acidic gas (HF gas) in the cracked gas and causing the reaction. In this case, the high-temperature cracked gas decomposed by the catalyst and the reaction water are heat-exchanged to preheat water, or the cracked gas and the exhaust gas containing perfluoride are heat-exchanged. A method for increasing the heat recovery rate by preheating the exhaust gas is described.

  However, the methods described in Patent Documents 1 and 2 have the following problems.

When heat is exchanged only between the high-temperature cracked gas and water, the water has a large heat capacity and large latent heat, so the surface temperature of the pipe (heat transfer tube) through which water flows in the heat exchanger (on the side where the high-temperature cracked gas comes into contact) Temperature) is partially 200 ° C. or lower. The cracked gas also contains SO _x produced by the decomposition of SF ₆ . When high-temperature cracked gas containing SO _x and moisture comes into contact with the heat exchanger tube of the heat exchanger having a surface temperature of 200 ° C. or lower, sulfuric acid is generated on the surface of the heat exchanger tube, and dew point corrosion may occur.

  In general, the heat exchanger tube of the heat exchanger needs to be made of metal from the viewpoints of heat resistance and heat conductivity when heat exchange is performed with a high-temperature gas of about 500 to 800 ° C. For this reason, in order to prevent dew point corrosion, it is necessary to take measures so that the surface of the heat transfer tube in contact with the high temperature gas does not become 200 ° C. or less, such as flowing water in the form of water vapor at 100 ° C. or higher. There is a problem that the heat recovery efficiency deteriorates.

  Furthermore, in patent documents 1 and 2, since the high-temperature decomposition gas is cooled by spraying a water spray at the lower part of the heat exchanger, there is a problem that minute splashes from the spray rise to the heat exchanger. is there. When the fine spray droplets adhere to the heat transfer tube of the metal heat exchanger, the acidic gas contained in the cracked gas dissolves in the attached droplets to form an acidic solution. For this reason, the problem that corrosion generate | occur | produces in a metal heat exchanger tube arises.

  In order to prevent the spray from splashing, there is a method of providing a baffle plate in the lower part of the heat exchanger to suppress the rise of the splash, but the pressure loss in the system increases because the flow of the decomposition gas is inhibited. Further, in the baffle plate, the upper surface is heated by a high-temperature gas, and the lower surface is cooled by spray droplets, so that the temperature difference between the upper and lower sides becomes large. Furthermore, the acidic solution is generated by the dissolution of the acidic gas due to the spray droplet adhesion, and the corrosion potential is increased. In order to take measures against these, there is a problem that expensive materials such as ceramics must be used.

  Patent Document 3 describes a method of cooling by exchanging heat between high-temperature cracked gas and external air, and a method of cooling by mixing external air in high-temperature cracked gas. When heat exchange is performed between the high-temperature cracked gas and external air, the heated air is not used and is released to the atmosphere, which is problematic in terms of heat recovery. On the other hand, when air is mixed in the cracked gas, the flow rate of the cracked gas is greatly increased. Since pressure loss and reaction rate depend on the gas flow rate, when trying to optimize the gas flow rate, the installed capacity of the acidic gas processing equipment (alkali scrubber, dry bag filter, etc.) installed downstream increases the exhaust gas. There is a problem that the capacity of the exhaust device (exhaust device, ejector, etc.) for exhausting increases.

In order to remove fluorine from wastewater generated by wet cleaning, a calcium salt (Ca salt), usually calcium hydroxide or calcium carbonate is used. Calcium hydroxide and calcium carbonate react with fluorine in the wastewater to generate poorly soluble calcium fluoride (CaF ₂ ) and precipitate it, thereby removing fluorine in the wastewater. In order to almost completely remove fluorine from the waste water, it is necessary to add calcium hydroxide or calcium carbonate several times the theoretical reaction amount.

  When the decomposition gas is cooled by general wet cleaning to remove acid gas, the higher the decomposition temperature of the exhaust gas, the higher the gas temperature after the decomposition treatment, so a large amount of water is required for cooling. . Semiconductor manufacturing factories and liquid crystal manufacturing factories consume a large amount of water in the cleaning process and the like, and there is a problem that the amount of wastewater further increases by performing the decomposition treatment of perfluoride. In addition, since acidic wastewater containing a large amount of fluorine is generated, a large-scale acidic wastewater treatment facility is required.

  In addition, in order to discharge wastewater containing fluorine to rivers and the sea, the fluorine concentration needs to be lower than the legal regulation value, and the fluorine in the wastewater must be separated and removed almost 100%. In the case where the fluorine concentration in the waste water is set to be lower than the legal regulation value, the waste water treatment facility becomes larger as the amount of waste water to be treated increases and the fluorine concentration contained in the waste water increases.

  In existing semiconductor manufacturing plants and liquid crystal manufacturing plants, if a perfluoride decomposition device is introduced into the production process using all perfluoride in order to suppress the emission of perfluoride to the atmosphere, the decomposition of perfluoride will occur. When all the high-concentration acidic gas to be generated is processed by wet cleaning, there is a problem that the amount of wastewater containing fluorine approaches the limit. In the future, all perfluorides emitted from the entire factories such as semiconductor manufacturing plants, liquid crystal manufacturing plants, and solar cell manufacturing plants will be decomposed, and wet cleaning will be performed on these cracked gases containing high concentrations of hydrogen fluoride. In some cases, a large amount of wastewater is generated, and there is a possibility that the existing wastewater treatment facilities installed in these factories cannot be treated.

  Recently, semiconductor manufacturing factories and liquid crystal manufacturing factories are working to reduce the amount of waste generated 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 plants, there are many processes that generate wastewater containing fluorine, and it is necessary to reduce the amount of wastewater containing fluorine.

In wet cleaning, precipitated calcium fluoride (CaF ₂ ) and excessively added Ca salt are separated from the wastewater as sludge containing excessive moisture. In order to reuse this sludge as a raw material for hydrofluoric acid, it is necessary to remove moisture and to make calcium fluoride contained in the sludge highly pure. For this reason, there is a problem that this sludge is not reused but becomes industrial waste.

  In the dry treatment, there is no problem of moisture removal. However, in order to obtain high-purity calcium fluoride suitable for reuse, supply of Ca salt to an acid gas removal device filled with Ca salt and the acidity It is necessary to appropriately control the discharge of Ca salt from the gas removal device.

  In addition to the above, when supplying Ca salt to two or more perfluoride decomposing apparatuses and recovering Ca salt reacted with acid gas from the apparatus, equipment for supplying and recovering per perfluoride decomposing apparatus ( There is a problem that the equipment capacity and installation space are increased. If the supply and collection frequency is increased as a countermeasure, a problem arises in that a new physical distribution system is constructed or the number of workers for the work is increased.

Japanese Patent Laid-Open No. 11-319485 JP 2003-340239 A JP 2006-312121 A

The object of the present invention is to solve the above-mentioned problems, that is, it is energy efficient and can prevent corrosion of the piping of the heat exchanger, and furthermore, the amount of waste water is greatly reduced and high purity calcium fluoride. An object of the present invention is to provide a perfluoride treatment method and a perfluoride treatment apparatus capable of efficiently recovering (CaF ₂ ). It is another object of the present invention to provide an efficient perfluoride treatment apparatus with a small equipment capacity and installation location.

As a result of intensive studies to solve the above problems, the present inventors have
(1) By exchanging heat between exhaust gas containing perfluoride and water or water vapor and cracked gas, it is possible to increase the heat recovery rate and prevent corrosion of the heat exchanger piping, and at the same time cracked gas Being able to cool the acid gas inside to a temperature suitable for dry processing,
(2) The amount of waste water can be greatly reduced by reacting Ca salt with cracked gas to remove acidic gas in the cracked gas,
(3) Supply of Ca salt to the acid gas removal device and reaction with the acid gas based on the concentration of the acid gas discharged from the acid gas removal device or the temperature of the Ca salt filled in the acid gas removal device By discharging the Ca salt, the amount of Ca salt discharged unreacted can be reduced, and a large amount of Ca salt containing high-purity CaF ₂ can be recovered.
(4) In the discharge / recovery of Ca salt from two or more perfluoride decomposing apparatuses and the supply of Ca salt to the apparatus, the use of a Ca salt discharge or supply apparatus using compressed air makes it possible to use perfluoride. The present inventors have found that the equipment capacity and installation location of the processing apparatus can be reduced and Ca salt can be efficiently discharged, recovered and supplied, and the present invention has been completed. The present invention includes the following items [1] to [15].

[1] (1) a step of preheating exhaust gas containing perfluoride and water or steam;
(2) a step of further heating the exhaust gas preheated in step (1) and water or water vapor;
(3) generating a cracked gas containing an acid gas by decomposing perfluoride contained in the exhaust gas heated in the step (2) with a catalyst;
(4) a step of cooling the cracked gas generated in the step (3) by exchanging heat with the exhaust gas of the step (1) and water or steam;
(5) including removing the acidic gas contained in the cracked gas cooled in the step (4) by contacting with a calcium salt, and the step (1) is generated in the step (3). A method for treating perfluoride, comprising preheating by heat exchange with cracked gas.

  [2] The step (1) is performed by exchanging heat between the exhaust gas containing perfluoride and a mixed gas in which water or water vapor is mixed with the cracked gas generated in the step (3). The method for treating perfluoride according to item [1], wherein:

  [3] The perfluoride treatment method according to [1] or [2], wherein the step (5) is performed using an acid gas removing device filled with a calcium salt.

[4] discharging the calcium salt reacted with the acid gas from the acid gas removing device; and
The perfluoride treatment method according to item [3], wherein a calcium salt is supplied to the acid gas removal device.

  [5] The item [4], wherein the discharge and supply of the calcium salt is performed based on the concentration of the acidic gas contained in the cracked gas after the acidic gas is removed by the acidic gas removing device. A method for treating perfluoride as described.

  [6] The perfluoride treatment method according to [4], wherein the discharge and supply of the calcium salt is performed based on the temperature of the calcium salt filled in the acidic gas removal device.

[7] Exhaust gas containing perfluoride, and a heater for heating water or steam;
A catalyst layer for decomposing the perfluoride;
An acidic gas removing device for removing acidic gas in the cracked gas generated by the decomposition of the perfluoride by contacting with a calcium salt;
A heat exchanger that preheats the exhaust gas and water or water vapor and cools the cracked gas by heat-exchanging the exhaust gas and water or water vapor and the cracked gas. Perfluoride treatment equipment.

  [8] The heat exchanger is a heat exchanger for exchanging heat between exhaust gas containing perfluoride and a mixed gas obtained by mixing water or water vapor and a cracked gas generated by decomposing the perfluoride. The apparatus for treating perfluoride as described in item [7] above.

[9] A calcium salt discharger for discharging the calcium salt reacted with the acid gas contained in the cracked gas from the acid gas removal device,
The apparatus for treating perfluoride according to item [7] or [8], further comprising a calcium salt supplier for supplying calcium salt.

[10] An acid gas concentration detector for detecting the concentration of the acid gas contained in the cracked gas discharged from the acid gas removing device;
The treatment of perfluoride according to item [9], further comprising a controller for controlling the calcium salt discharger and the calcium salt supplier based on the measured concentration of the acid gas concentration detector. apparatus.

[11] A temperature detector for detecting the temperature of the calcium salt filled in the acidic gas removal device;
The perfluoride treatment apparatus according to item [9], further comprising a control device that controls the calcium salt discharger and the calcium salt supply unit based on a temperature measured by the temperature detector.

[12] Two or more perfluoride decomposition apparatuses;
A calcium salt tank for supplying calcium salt to the perfluoride decomposition apparatus;
A calcium salt supply device for supplying a certain amount of calcium salt from the calcium salt tank to the perfluoride decomposition device;
A calcium salt supply pipe provided with a calcium salt supply switching mechanism for supplying calcium salt to two or more perfluoride decomposition apparatuses using compressed air;
A compressed air supply device for supplying compressed air for transferring calcium salt from the calcium salt supply device to the perfluoride decomposition device to a calcium salt supply pipe;
A perfluoride processing apparatus including a calcium salt supply device, a calcium salt supply switching mechanism, and a control device for controlling a compressed air supply device based on a calcium salt supply signal from a perfluoride decomposition device.

  [13] The perfluoride treatment apparatus according to item [12], wherein the perfluoride decomposition apparatus includes a heater, a catalyst layer, a heat exchanger, and an acid gas removal device.

[14] Two or more perfluoride decomposition apparatuses;
A calcium salt recovery tank for recovering calcium salt discharged from the perfluoride decomposition apparatus;
A calcium salt recovery pipe equipped with a calcium salt recovery switching mechanism for recovering calcium salt using compressed air from two or more perfluoride decomposition devices;
A compressed air supply device for supplying compressed air for transferring calcium salt from the perfluoride decomposition apparatus to a calcium salt recovery tank to a calcium salt discharge tank and the calcium salt recovery pipe;
A perfluoride processing apparatus including a calcium salt recovery switching mechanism and a control device for controlling a compressed air supply device based on a calcium salt discharge signal from the perfluoride decomposition apparatus.

  [15] The perfluoride treatment apparatus according to item [14], wherein the perfluoride decomposition apparatus includes a heating device, a catalyst layer, a heat exchanger, and an acid gas removal device.

  According to the method of items [1] and [2], heat exchange is performed between the high-temperature decomposition gas generated by decomposition of perfluoride, the exhaust gas containing perfluoride, and water or water vapor. It is possible to reduce the energy for heating the exhaust gas containing the chemicals, and to cool the cracked gas to a temperature suitable for dry processing using Ca salt without using water or outside air. Corrosion of the piping can be prevented.

  According to the method of the items [3] and [4], in addition to the effects obtained in the above items [1] and [2], dry treatment using a Ca salt is performed to remove the acidic gas contained in the cracked gas Therefore, the amount of drainage can be reduced as compared with conventional wet cleaning.

According to the method of the items [5] and [6], in addition to the effects obtained in the above items [1] to [4], the amount of unreacted Ca salt in the acid gas removal device is further reduced, and the Ca salt it is possible to reduce the consumption of, Ca salt containing CaF ₂ high purity can be more collected, recovered Ca salt containing a high-purity CaF ₂ was as valuable resources such as raw material hydrofluoric acid Can be reused.

  By using the apparatus according to the items [7] and [8], heat exchange is performed between the high-temperature decomposition gas generated by the decomposition of perfluoride, the exhaust gas containing perfluoride, and water or water vapor. The energy for heating the exhaust gas containing the chemical can be reduced, and the decomposition gas can be cooled to a temperature suitable for dry treatment using Ca salt without using water or outside air.

  If the apparatus of the item [9] is used, in addition to the effect obtained by using the apparatus of the above items [7] and [8], a dry treatment using Ca salt is performed to remove the acidic gas contained in the cracked gas. As a result, the amount of drainage can be reduced as compared with conventional wet cleaning.

If the apparatus of item [10] and [11] is used, in addition to the effect acquired by using the apparatus of said [7]-[9], the amount of unreacted Ca salt in an acidic gas removal apparatus will be reduced further. , it is possible to reduce the consumption of Ca salt, Ca salt containing CaF ₂ high purity can be more collected, Ca salt containing high purity CaF ₂ recovered, such as the raw material of hydrofluoric acid It can be reused as a valuable resource.

  If the apparatus of item [12] and [13] is used, the supply of Ca salt to a plurality of perfluoride decomposition apparatuses can be efficiently realized with a simple system configuration.

  If the apparatus of the items [14] and [15] is used, the recovery of the Ca salt reacted with the acid gas from the plurality of perfluoride decomposition apparatuses can be efficiently realized with a simple system configuration.

It is a conceptual diagram of a perfluoride decomposition processing system. It is a block diagram of the processing apparatus of the perfluoride using the exhaust gas and water preheating method containing the perfluoride by a heat exchanger. It is a block diagram of the processing apparatus of the perfluoride using the exhaust gas and water preheating method containing the perfluoride by a heat exchanger. It is a block diagram of the processing apparatus of perfluoride using the water preheating method using a two-fluid nozzle. It is a block diagram of the processing apparatus of perfluoride including the discharge | emission and supply method of Ca salt by HF gas density | concentration detection. It is a block diagram of the processing apparatus of perfluoride including the discharge | emission and supply method of Ca salt by the temperature detection of Ca salt. It is a block diagram of the supply system of Ca salt with respect to several perfluoride decomposition | disassembly apparatuses. It is a block diagram of the supply system of Ca salt with respect to several perfluoride decomposition | disassembly apparatuses. It is a configuration diagram of a discharge-recovery system Ca salt containing CaF ₂ for a plurality of over-fluoride cracker.

  The perfluoride decomposition method of the present invention, the apparatus used in this method, and the Ca salt supply / recovery system for a plurality of perfluoride decomposition apparatuses will be described in detail below.

  In this specification, “exhaust gas” refers to a gas generated and discharged from a semiconductor manufacturing process, a liquid crystal manufacturing process, a solar cell manufacturing process, or the like, and “mixed gas” refers to the exhaust gas, water, Alternatively, a gas mixed with water vapor is referred to, and the “decomposition gas” refers to a gas in which the mixed gas is decomposed by heating and decomposing with a catalyst, “Acid gas” refers to a gas such as hydrogen fluoride (HF) in the cracked gas.

  In the present invention, in order to increase the thermal efficiency of the perfluoride treatment apparatus and prevent corrosion of the piping, a high-temperature cracked gas generated after cracking the exhaust gas containing perfluoride with a catalyst and the exhaust gas containing perfluoride And by exchanging heat with water or water vapor, the exhaust gas and water or water vapor are preheated as part of the heating step necessary for perfluoride decomposition, and at the same time, the cracked gas is cooled. At this time, the exhaust gas containing perfluoride and water or steam may be separately supplied to the heat exchanger and mixed after preheating, and the exhaust gas containing perfluoride and water may be mixed in the heat exchanger. Alternatively, steam may be mixed and preheated.

Further, the acid gas in the cracked gas is removed by an acid gas removing device filled with Ca salt in order to reduce the amount of drainage. At this time, as the Ca salt, for example, Ca (OH) ₂ , CaCO ₃ , CaO, or a mixture thereof can be used. Further, the Ca salt may be powder, but for example, a product molded into a columnar shape, a spherical shape, or the like may be used.

Further, by reducing the amount of Ca salt discharged from the acid gas removal device in an unreacted state, the consumption of Ca salt is reduced, and this acidic salt is recovered in order to recover a large amount of Ca salt containing high-purity CaF _2. The discharge of the Ca salt reacted with the gas and the supply of the Ca salt to the acid gas removal device are adjusted to the concentration of the acid gas discharged from the acid gas removal device or the temperature of the Ca salt filled in the acid gas removal device. Based on.

A method for discharging and supplying Ca salt based on the concentration of acid gas discharged from the acid gas removing device is as follows. The Ca salt filled in the acidic gas removing device comes into contact with the cracked gas containing HF gas supplied from the lower part of the acidic gas removing device, and changes to CaF ₂ by reacting with the HF gas. In the acidic gas removal device, when the decomposition salt gas is supplied from the lower part of the Ca salt, the reaction position of the Ca salt and the HF gas moves from the lower part to the upper part. Low concentration HF gas of several ppm order is discharged from the outlet of the apparatus. The outlet pipe of the acid gas removal device is provided with an HF gas concentration detector. When a certain concentration of HF gas is detected, a detection signal is output to the control device. At this time, the concentration detection of the HF gas may be one that directly detects the HF concentration in the exhaust gas. Once the HF gas is absorbed in water or an alkali solution, it is indirectly detected as the fluorine ion concentration in water. It may be a thing.

The control device transmits an operation signal from the control device to the Ca salt discharger based on the detection signal of the HF gas concentration. In the Ca salt discharger, based on the operation signal, among the Ca salts filled in the acid gas removal device, the Ca salt containing CaF ₂ at a certain height from the lower portion with high purity is passed through the Ca salt discharger. To discharge to the Ca salt discharge tank. An operation signal is transmitted from the control device to the Ca salt supplier. In the Ca salt supply device, the Ca salt is acidified from the Ca salt supply tank connected to the acid gas removal device through the Ca salt supply device so as to be equivalent to the Ca salt containing high purity CaF ₂ discharged. Ca salt is supplied to the gas removal device.

Moreover, the method of discharging | emitting and supplying Ca salt based on the temperature of Ca salt with which the acidic gas removal apparatus was filled is as follows. When the Ca salt filled in the acid gas removing device reacts with HF gas, the temperature rises due to an exothermic reaction. The filled Ca salt changes to CaF ₂ by reacting with HF gas, and the position of the exothermic reaction moves from the lower part to the upper part. Along with this, the temperature rise position of the filled Ca salt also moves. This temperature rise is detected by a temperature detector, and a detection signal is output to the control device. The discharge and supply of Ca salt by the subsequent control device is performed in the same manner as the method based on the HF gas concentration described above. In addition, temperature detection may be performed by outputting the detection signal which detected the temperature fall after reaction of Ca salt and HF gas was complete | finished to a control apparatus.

  A method for supplying Ca salt to two or more perfluoride decomposing apparatuses included in the present invention and discharging / recovering the Ca salt will be described below.

  An apparatus comprising a Ca salt tank, a compressed air supply device, a Ca salt supply device, a Ca salt supply pipe, a Ca salt supply switching mechanism, and a control device for supplying Ca salt to two or more perfluoride decomposition devices. , On the basis of a Ca salt supply signal from the perfluoride decomposition apparatus to the controller, the Ca salt supply switching mechanism switches the Ca salt supply piping, and compressed air is used to supply the Ca salt to the perfluoride decomposition apparatus. Supply.

In addition, a Ca salt recovery tank, a compressed air supply device, a Ca salt recovery pipe, a Ca salt recovery switching mechanism and a control device are used to discharge Ca salt that has reacted with acid gas from two or more perfluoride decomposition devices. In the apparatus, the Ca salt recovery switching mechanism switches the Ca salt recovery pipe based on the Ca salt recovery signal from the perfluoride decomposition apparatus to the control unit, and the compressed air is used to switch from the perfluoride decomposition apparatus. The Ca salt containing CaF ₂ with high purity is recovered.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the scope of the present invention is not limited thereto.

[Example 1]
A perfluoride decomposition treatment system which is a preferred embodiment of the present invention is shown in FIGS.
Exhaust gas containing perfluoride discharged from an etching apparatus, ashing apparatus or CVD apparatus (not shown) in the semiconductor manufacturing process, liquid crystal manufacturing process or solar cell manufacturing process, and water or water vapor used for the decomposition reaction are heated. It is supplied to the exchanger 2.

  In the heat exchanger 2, heat is recovered from the high-temperature cracked gas after decomposing the perfluoride, and the exhaust gas containing the perfluoride and water or water vapor used for the decomposition reaction are preheated to about 200 to 300 ° C. . In addition, the surface of the heat transfer tube in contact with the high-temperature decomposition gas through which the exhaust gas containing perfluoride and water or water vapor used for the decomposition reaction flow becomes 200 ° C. or higher.

  In the heat exchanger, as shown in FIG. 3, exhaust gas containing perfluoride and water or steam may be separately supplied to the heat exchanger and mixed after preheating. Further, in the heat exchanger, the exhaust gas containing perfluoride and water or steam may be mixed and preheated. The heat exchanger may be a plate fin or shell-and-tube, and has a double-pipe structure in which a high-temperature cracked gas flows through the inner pipe, an exhaust gas containing low-temperature perfluoride, and water or steam flow through the outer pipe. Heat exchange may be used. The high-temperature cracked gas, the exhaust gas containing the low-temperature perfluoride, and water or water vapor may flow in the heat exchanger in a counterflow or in parallel flow.

  The mixed gas of the exhaust gas containing perfluoride and water or water vapor preheated by the heat exchanger is supplied to the perfluoride decomposition section 1. The perfluoride decomposition unit 1 includes a first heating device 11, a second heating device 12, and a catalyst 13. When the amount of processing gas is small, it is possible to heat up to a temperature at which the decomposition reaction occurs only with the first heating device 11, and the second heating device 12 can be eliminated. The first heating device 11 is supplied with a preheated mixed gas of exhaust gas containing perfluoride and water or water vapor, and is heated to about 300 ° C. to 600 ° C. by the heater 14. Further, the mixed gas is heated to about 700 to 800 ° C. by the heater 15 in the second heating device 12. The mixed gas heated to about 700 to 800 ° C. is supplied to the catalyst 13. In the catalyst 13, perfluoride and water react to decompose perfluoride. 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. As the catalyst, for example, a catalyst containing aluminum oxide and further containing at least one oxide selected from Zn, Ni, Ti, F, Sn, Co, Zr, Ce and Si can be used.

  An example of a perfluoride decomposition reaction formula is shown in the following formulas (1) to (4).

CF ₄ + 2H ₂ O → CO ₂ + 4HF (Formula 1)
CHF ₃ + 1 / 2O ₂ + H ₂ O → CO ₂ + 3HF (Formula 2)
C ₂ F ₆ + 3H ₂ O + 1 / 2O ₂ → 2CO ₂ + 6HF (Equation 3)
SF ₆ + 3H ₂ O → SO ₃ + 6HF (Formula 4)
The cracked gas generated by the cracking reaction of the catalyst 13 contains a high concentration acidic gas (hydrogen fluoride gas: HF gas). In the above reaction formula (1), when the exhaust gas containing CF ₄ 1 volume%, the 4-fold of HF CF ₄ is produced by the decomposition reaction, the decomposition gas, contains 4 vol% of a high concentration of HF Discharged. The cracked gas is discharged from the catalyst 13 at a high temperature of about 500 to 800 ° C.

  A cracked gas containing a high-temperature and high-concentration acidic gas (HF gas) is supplied to the heat exchanger 2. In the heat exchanger 2, the cracked gas containing high-temperature and high-concentration HF gas is cooled to about 300 to 500 ° C. by exchanging heat with exhaust gas containing perfluoride and water or steam. The cooled cracked gas is supplied to the acid gas removal unit 3 filled with Ca salt.

  The acidic gas removing unit 3 includes an acidic gas removing device 31 filled with a Ca salt 30, a Ca salt supply tank 32, a Ca salt supply device 33 that supplies Ca salt from the Ca salt supply tank 32 to the acidic gas removal device 31, and a high It consists of a Ca salt discharger 34 that discharges Ca salt that has reacted with HF gas at a concentration, and a Ca salt discharge tank 35 that stores Ca salt discharged from the Ca salt discharger.

In the acidic gas removal device 31, the Ca salt 30 is filled, and the HF gas is removed by the reaction of the HF gas and the Ca salt contained in the cracked gas. On the other hand, Ca salt reacts with HF gas to become CaF ₂ (calcium fluoride). The HF gas concentration in the cracked gas discharged from the acid gas removing device 31 is 3 ppm or less, and is exhausted via the ejector 4. In addition, as a method for sucking and discharging the cracked gas other than the ejector, an exhaust fan can be used.

As the Ca salt, for example, Ca (OH) ₂ , CaCO ₃ , CaO, or a mixture thereof can be used. Further, the Ca salt may be powder, but for example, a cylindrical or spherical shape may be used. The Ca salt is a mixture of Ca (OH) ₂ and CaCO ₃ and has a cylindrical shape, and the mixing ratio is Ca (OH) ₂ : CaCO ₃ = 50 to 80% by mass: 20 to 50 The thing of the mass% is preferable. A mixture of Ca (OH) ₂ and CaCO ₃ has an advantage that it is easy to handle because it has good moldability and less pulverization during supply and discharge.

The Ca salt 30 filled in the acid gas removal device 31 reacts with the HF gas to become CaF ₂ and is consumed. Therefore, the Ca salt containing CaF ₂ is discharged from the acid gas removal device 31 continuously or intermittently, And it is necessary to supply Ca salt to the acidic gas removal apparatus 31 continuously or intermittently. The discharge of Ca salt containing CaF ₂ from the acid gas removal device 31 is continuously or intermittently performed to the Ca salt discharge tank 35 via the Ca salt discharger 34. As the Ca salt discharger 34, a discharge device such as a valve, a rotary feeder, a screw feeder or a conveyor can be used. The supply of the Ca salt to the acid gas removing device 31 is performed continuously or intermittently from the Ca salt supply tank 32 via the Ca salt supply unit 33. As Ca salt supply device 33, supply devices, such as a valve, a rotary feeder, a screw feeder, or a conveyor, can be used.

[Example 2]
FIG. 4 shows an embodiment in which water is supplied to the heat exchanger as two fluids, compressed air and water. When the exhaust gas containing perfluoride and water are mixed in the heat exchanger 2 to form water, the water is made into a fine mist so that the water is uniformly mixed with the water in contact with the gas. The surface area of the water becomes large and water is easily vaporized by heat exchange.

  Although it is possible to make water a fine mist by injecting water from a nozzle, there is a method of injecting compressed air and water from a two-fluid nozzle in order to further refine the water. The nozzle 21 is provided in the heat exchanger 2, and compressed air and water are supplied to the nozzle 21 and sprayed from the nozzle 21 as two fluids. The heat exchanger 2 is preheated by mixing fine mist in the exhaust gas containing perfluoride and exchanging heat with the high-temperature cracked gas.

[Example 3]
FIG. 5 shows that an HF gas concentration detector is provided in the exhaust gas pipe discharged from the acidic gas removal device, and a signal from the HF gas concentration detector is output to the control device. The Example which controls Ca salt supply device is shown.

The Ca salt containing CaF ₂ discharged from the acid gas removal device can be reused as a raw material for hydrofluoric acid as the CaF ₂ content is higher, and the consumption of the supplied Ca salt should be reduced. Can do. Therefore, it is necessary to take out the Ca salt from the acidic gas removal device in a state where the content ratio of CaF ₂ is increased.

The Ca salt filled in the acid gas removing device 31 comes into contact with the cracked gas containing HF gas supplied from the lower part of the acid gas removing device, and changes to CaF ₂ by reacting with the HF gas. In the acidic gas removal device 31, the reaction position of the Ca salt and the HF gas moves from the lower part to the upper part, and when it exceeds a certain position, the low concentration HF gas of several ppm order from the outlet of the acidic gas removal device 31. Will be discharged. An HF gas concentration detector 51 is provided at the outlet pipe of the acid gas removal device 31, and outputs a detection signal to the control device 5 when a certain concentration of HF gas is detected. The HF gas concentration detector 51 may directly detect the HF concentration in the exhaust gas, or may temporarily detect the fluorine ion concentration in water by absorbing the HF gas in water or an alkali solution.

In the control device 5, an operation signal is transmitted from the control device 5 to the Ca salt discharger 34 based on the detection signal of the HF gas concentration. In the Ca salt discharger, based on the operation signal, among the Ca salts filled in the acidic gas removal device 31, the Ca salt containing CaF ₂ at a certain height from the lower portion with high purity is replaced with the Ca salt discharger 34. It discharges to Ca salt discharge tank 35 via. At this time, the recovered Ca salt containing CaF ₂ contains 80 to 95% by mass of CaF ₂ .

In addition, an operation signal is transmitted from the control device 5 to the Ca salt supplier 33. In the Ca salt supply device 33, the Ca salt is supplied from the Ca salt supply tank 32 at the upper part of the acidic gas removing device 31 through the Ca salt supply device 33 so as to be equivalent to the Ca salt containing discharged high purity CaF _2. Then, the Ca salt is supplied to the acid gas removing device 31.

[Example 4]
FIG. 6 shows an embodiment in which the temperature of the Ca salt filled in the acidic gas removing device is detected, the Ca salt containing CaF ₂ is discharged from the acidic gas removing device, and the Ca salt is supplied to the acidic gas removing device. Show.

When the Ca salt filled in the acid gas removing device 31 reacts with the HF gas, the temperature rises due to an exothermic reaction. The filled Ca salt reacts with HF gas to change to CaF ₂ , and the position of the exothermic reaction moves from the lower part to the upper part. Along with this, the temperature rise position of the filled Ca salt also moves. This temperature rise is detected by the temperature detector 52, and a detection signal is output to the control device 5. In addition, temperature detection may be performed by outputting the detection signal which detected the temperature fall to the control apparatus 5 after reaction of Ca salt and HF gas was complete | finished.

In the control device 5, as in the third embodiment, the operation signal is transmitted to the Ca salt discharger 34 and the Ca salt supply device 33 to discharge Ca salt containing CaF ₂ with high purity, and the acid gas removal device 31. Supply Ca salt to

[Example 5]
FIGS. 7 and 8 show a method of supplying Ca salt using compressed air when two or more perfluoride decomposition apparatuses of FIGS. 5 and 6 are installed. The Ca salt tank 6 is provided with a Ca salt supply device 61 at the bottom. The Ca salt supply device 61 and the Ca salt supply tanks of the two perfluoride decomposition apparatuses use a compressed air to supply Ca salt to the Ca salt supply tanks of the two perfluoride decomposition apparatuses. The Ca salt supply pipe 63 is provided with a branch. The Ca salt supply pipe 63 is provided with valves 110a and 110b as a Ca salt supply switching mechanism for each perfluoride removing device. In addition, the Ca salt supply apparatus 61 can utilize a valve, a rotary feeder, a screw feeder, a conveyor, or the like.

  Upon receiving the Ca salt supply output signal from the control device 5a of the perfluoride decomposition apparatus 100a, the control device 10 transmits an operation signal to the Ca salt supply device 61, an open signal to the valve 110a, and a close signal to the valve 110b. In the salt tank 6, the Ca salt is supplied to the lower part by the operation of the Ca salt supply device 61.

  The Ca salt supplied to the lower portion passes through the Ca salt supply pipe 63 by compressed air from the compressed air supply device 62, and is supplied to the Ca salt storage tank 8a via the valve 110a. In the Ca salt storage tank 8a, only compressed air is exhausted and only Ca salt remains. After Ca salt is supplied to the Ca salt storage tank 8a, a stop signal of the Ca salt supply device 61, a closing signal of the valve 110a, and an opening signal of the valve 111a are transmitted from the control device 10, and the Ca salt of the perfluoride decomposition device 100a is transmitted. Ca salt is supplied to the supply tank 32a. After Ca salt is supplied to the Ca salt supply tank 32a, a closing signal is transmitted from the control device 10 to the valve 111a to close the valve 111a.

  On the other hand, when supplying Ca salt to the perfluoride decomposition apparatus 100b, the control apparatus 10 that has received an output signal of Ca supply from the control apparatus 5b of the fluoride decomposition apparatus 100b sends an operation signal to the Ca salt supply apparatus 61. Then, an open signal is transmitted to the valve 110b and a close signal is transmitted to the valve 110a. In the Ca salt tank 6, Ca salt is supplied to the lower part by the operation of the Ca salt supply device 61.

  The Ca salt supplied to the lower portion passes through the Ca salt supply pipe 63 by compressed air, and is supplied to the Ca salt storage tank 8b via the valve 110b. Only the compressed air is exhausted in the Ca salt storage tank 8b, and only the Ca salt remains. After the Ca salt is supplied to the Ca salt storage tank 8b, the controller 10 transmits a stop signal of the Ca salt supply device 61, a close signal of the valve 110b, and an open signal of the valve 111b, and the Ca salt of the perfluoride decomposition device 100b. Supply to the supply tank 32b. After being supplied to the Ca salt supply tank 32b, a closing signal is transmitted from the control device 10 to the valve 111b to close the valve 111b.

  When there are two perfluoride decomposition apparatuses, the valve 110a and the valve 110b of the supply pipe may be switched with one three-way valve. Further, even if the control device 10 has the control function of the control devices 5a and 5b and the two perfluoride decomposition devices are controlled only by the control device 10, a similar system can be constructed. Although FIG. 7 shows a method of supplying Ca salt to two perfluoride decomposition apparatuses, this system can be applied to a plurality of three or more units in the same manner. .

[Example 6]
FIG. 8 shows a method of supplying Ca salt without using the Ca salt storage tank of FIG. Upon receiving the Ca salt supply output signal from the control device 5a of the perfluoride decomposition apparatus 100a, the control device 10 sends an operation signal to the Ca supply device 61, an open signal to the valves 110a, 112a and 113a, and a valve 110b. A close signal is transmitted to the valve 112b and the valve 113b. In the Ca salt tank 6, Ca salt is supplied to the lower part by the operation of the Ca salt supply device.

  The Ca salt supplied to the lower portion passes through the Ca salt supply pipe 63 together with the compressed air, and is supplied to the Ca salt supply tank 32a via the valve 110a. In the Ca salt supply tank 32a, only compressed air is exhausted via the valve 113a, and only the Ca salt remains. After the Ca salt is supplied to the Ca salt supply tank 32a, the control device 10 transmits a stop signal for the Ca salt supply device 61 and signals for closing the valves 110a, 112a, and 113a.

  On the other hand, when supplying the Ca salt to the perfluoride decomposition apparatus 100b, the control apparatus 10 that has received the output signal of the Ca salt supply from the control apparatus 5b of the perfluoride decomposition apparatus 100b operates the Ca salt supply apparatus 61. The signal is transmitted to the valves 110b, 112b and 113b, and the close signal is transmitted to the valves 110a, 112a and 113a. In the Ca salt tank, Ca salt is supplied to the lower part by the operation of the Ca salt supply device 61.

  The Ca salt supplied to the lower portion passes through the Ca salt supply pipe 63 together with the compressed air, and is supplied to the Ca salt supply tank 32b via the valve 110b. In the Ca salt supply tank 32b, only compressed air is exhausted via the valve 113b, leaving only the Ca salt. After the Ca salt is supplied to the Ca salt supply tank 32b, the control device 10 transmits a stop signal for the Ca salt supply device 61 and signals for closing the valves 110b, 112b, and 113b.

[Example 7]
FIG. 9 shows a method for discharging and recovering a Ca salt containing CaF ₂ using compressed air when two or more perfluoride decomposing apparatuses shown in FIGS. 5 and 6 are installed. Compressed air piping is connected to the Ca salt discharge tanks 35a and 35b of the perfluoride decomposition apparatuses 100a and 100b, and the Ca salt recovery tank 9 and the Ca salt discharge tanks 35a and 35b are connected by a Ca salt recovery pipe 64. . The Ca salt recovery pipe 64 is provided with a valve as a Ca salt recovery switching mechanism. Moreover, the control apparatus 10 which controls opening and closing of those valves is provided.

  Upon receiving the Ca salt discharge output signal from the control device 5a of the perfluoride decomposition apparatus 100a, the control device 10 transmits an open signal to the valves 105a and 106a and a close signal to the valves 105b and 106b. In the perfluoride decomposition apparatus 100a, Ca salt is discharged to the Ca salt discharge tank 35a by the control of the control apparatus 5a shown in the third and fourth embodiments. Compressed air is supplied to the Ca salt discharge tank 35a via the valve 106a. The compressed air and the Ca salt are recovered in the Ca salt recovery tank 9 via the valve 105a. Only the compressed air is exhausted in the Ca salt recovery tank 9, and the Ca salt remains in the Ca salt recovery tank 9. When the Ca salt discharge from the Ca salt discharge tank 35a is completed, the control device 10 transmits a closing signal for the valves 105a and 106a.

  On the other hand, when discharging the Ca salt from the perfluoride decomposition apparatus 100b, the control apparatus 10 that has received the Ca salt discharge output signal from the control apparatus 5b of the perfluoride decomposition apparatus 100b opens the valves 105b and 106b. Then, a close signal is transmitted to the valves 105a and 106a. In the perfluoride decomposition apparatus 100b, Ca salt is discharged into the Ca salt discharge tank 35b under the control of the control device 5b shown in the third and fourth embodiments. Compressed air is supplied to the Ca salt discharge tank 35b via the valve 106b. The compressed air and the Ca salt are recovered in the Ca salt recovery tank 9 via the valve 105b. In the Ca salt recovery tank 9, only compressed air is exhausted, and Ca salt remains in the Ca salt recovery tank 9. When the Ca salt discharge from the Ca salt discharge tank 35b is completed, the control device 10 transmits a closing signal for the valves 105b and 106b.

  A similar system can be constructed by providing the control device 10 with the control functions of the control devices 5a and 5b and controlling the two perfluoride decomposing devices with the control device 10 alone.

FIG. 9 shows a method for discharging and recovering Ca salt containing CaF ₂ from _two perfluoride decomposing devices, but this system should be applied to three or more units in the same way. Can do.

[Example 8]
Table 1 shows changes in gas temperature when heat exchange is performed between exhaust gas and water and cracked gas in the apparatus having the configuration of Example 2. In the apparatus, exhaust gas and water were mixed with a heat exchanger and preheated. The preheated mixed gas was heated to 400 ° C. with the first heating device, further heated to 750 ° C. with the second heating device, and supplied to the catalyst layer. As the catalyst, aluminum oxide and nickel oxide were used. In addition, the heat exchanger has a double-pipe structure, and the exhaust gas and water and the cracked gas flowed in the heat exchanger in parallel flow. The acid gas was discharged from the acid gas removing device using an ejector. Moreover, the supply of Ca salt to the acidic gas removal apparatus was continuously performed using a rotary feeder, and the discharge of Ca salt from the acidic gas removal apparatus was continuously performed using a rotary feeder. The Ca salt charged and supplied to the acid gas removal device is a mixture of Ca (OH) ₂ and CaCO ₃ and has a cylindrical shape, and the mixing ratio is Ca (OH) ₂ : CaCO ₃ = 35: 75% by mass was used.

上記結果より、本発明の方法および装置を用いることにより、排ガスと水とを、過弗化物の分解に必要な加熱の前段階として適切に予熱することができるとともに、分解ガスを、Ｃａ塩を用いた乾式処理に適した温度に冷却できることが解る。

From the above results, by using the method and apparatus of the present invention, exhaust gas and water can be appropriately preheated as a pre-heating step necessary for the decomposition of perfluoride, and the decomposition gas can be converted into Ca salt. It can be seen that it can be cooled to a temperature suitable for the dry treatment used.

DESCRIPTION OF SYMBOLS 1, 1a, 1b ... Perfluoride decomposition | disassembly part 2, 2a, 2b ... Heat exchanger 3 ... Acid gas removal part 4 ... Ejector 5, 5a, 5b ... Control apparatus 6 ... Ca salt tanks 8a, 8b ... Ca salt storage tank 9 ... Ca salt recovery tank 10 ... Control device 11 ... First heating device 12 ... Second heating device 13 ... Catalyst 14, 15 ... Heater 21 ... Nozzle 30, 30a, 30b ... Ca salt 31, 31a, 31b ... Acid gas removal device 32, 32a, 32b ... Ca salt supply tank 33, 33a, 33b ..Ca salt feeder 34, 34a, 34b ... Ca salt discharger 35,35a, 35b ... Ca salt discharge tank 51,51a, 51b ... HF gas concentration detector 52 ... Temperature detector 61 ... Ca salt supply device 62 ... Compressed air supply device 63 ... Ca salt supply pipe 64 ... Ca salt recovery pipe 100a, 100b ... perfluoride decomposition apparatus 105a, 105b, 106a, 106b, 110a, 110b, 111a, 111b, 112a, 112b, 113a, 113b ···valve

Claims (13)

(1) a step of preheating exhaust gas containing perfluoride and water or water vapor;
(2) a step of further heating the exhaust gas preheated in step (1) and water or water vapor;
(3) generating a cracked gas containing an acid gas by decomposing perfluoride contained in the exhaust gas heated in the step (2) with a catalyst;
(4) a step of cooling the cracked gas generated in the step (3) by exchanging heat with the exhaust gas of the step (1) and water or steam;
(5) a step of removing the acidic gas contained in the cracked gas cooled in the step (4) by contacting with the calcium salt,
Characterized in that said step (1) is seen containing a preheat by heat exchange with the decomposition gas generated in step (3), and, exhaust gas containing excessive fluoride, and, at the same time the heat exchange with water or steam And a method for treating perfluoride.   The step (1) is performed by exchanging heat between the exhaust gas containing perfluoride and a mixed gas in which water or water vapor is mixed with the cracked gas generated in the step (3). The method for treating perfluoride according to claim 1.   The method for treating perfluoride according to claim 1 or 2, wherein the step (5) is performed using an acidic gas removing device filled with a calcium salt. Discharging the calcium salt reacted with the acid gas from the acid gas removing device; and
4. The perfluoride treatment method according to claim 3, wherein a calcium salt is supplied to the acid gas removing device.   The perfluorination according to claim 4, wherein the discharge and supply of the calcium salt is performed based on the concentration of the acidic gas contained in the cracked gas after the acidic gas is removed by the acidic gas removing device. Method for processing chemicals.   5. The method for treating perfluoride according to claim 4, wherein the discharge and supply of the calcium salt is performed based on the temperature of the calcium salt filled in the acidic gas removing device. An exhaust gas containing perfluoride and a heater for heating water or steam;
A catalyst layer for decomposing the perfluoride;
An acidic gas removing device for removing acidic gas in the cracked gas generated by the decomposition of the perfluoride by contacting with a calcium salt;
A heat exchanger that preheats the exhaust gas and water or steam and cools the cracked gas by simultaneously exchanging heat between the exhaust gas and water or steam and the cracked gas. Perfluoride processing equipment.   The heat exchanger is a heat exchanger for exchanging heat between an exhaust gas containing perfluoride and a mixed gas mixed with water or water vapor and a cracked gas generated by decomposing the perfluoride. The apparatus for processing perfluoride according to claim 7. A calcium salt discharger for discharging the calcium salt reacted with the acidic gas contained in the cracked gas from the acidic gas removing device;
The apparatus for treating perfluoride according to claim 7 or 8, further comprising a calcium salt supplier for supplying calcium salt. An acid gas concentration detector for detecting the concentration of the acid gas contained in the cracked gas discharged from the acid gas removing device;
10. The perfluoride treatment apparatus according to claim 9, further comprising a controller for controlling the calcium salt discharger and the calcium salt supplier based on a measured concentration of the acid gas concentration detector. . A temperature detector for detecting the temperature of the calcium salt filled in the acid gas removal device;
The perfluoride treatment apparatus according to claim 9, further comprising a control device that controls the calcium salt discharger and the calcium salt supply unit based on a temperature measured by the temperature detector. Two or more perfluoride decomposers,
A calcium salt tank for supplying calcium salt to the perfluoride decomposition apparatus;
A calcium salt supply device for supplying a certain amount of calcium salt from the calcium salt tank to the perfluoride decomposition device;
A calcium salt supply pipe provided with a calcium salt supply switching mechanism for supplying calcium salt to two or more perfluoride decomposition apparatuses using compressed air;
A compressed air supply device for supplying compressed air for transferring calcium salt from the calcium salt supply device to the perfluoride decomposition device to a calcium salt supply pipe;
Based on the signal of the calcium salt supply from excessive fluoride cracker, viewed contains a control device for controlling calcium salt feeder, a calcium salt supply switching mechanism and the compressed air supply device,
The perfluoride decomposing apparatus comprises:
An exhaust gas containing perfluoride and a heater for heating water or steam;
A catalyst layer for decomposing the perfluoride;
An acidic gas removing device for removing acidic gas in the cracked gas generated by the decomposition of the perfluoride by contacting with a calcium salt;
The flue gas, and a water or water vapor, by simultaneously heat exchanged with the decomposition gas, the flue gas, and, together with preheated water or steam, the heat exchanger and the including perfluorinated cooling the decomposition gas Chemical processing equipment. Two or more perfluoride decomposers,
A calcium salt recovery tank for recovering calcium salt discharged from the perfluoride decomposition apparatus;
A calcium salt recovery pipe equipped with a calcium salt recovery switching mechanism for recovering calcium salt using compressed air from two or more perfluoride decomposition devices;
A compressed air supply device for supplying compressed air for transferring calcium salt from the perfluoride decomposition apparatus to a calcium salt recovery tank to a calcium salt discharge tank and the calcium salt recovery pipe;
Based on the calcium salt discharge signals from excessive fluoride decomposition apparatus, and a control device for controlling the calcium salt recovery switching mechanism and the compressed air supply device seen including,
The perfluoride decomposing apparatus comprises:
An exhaust gas containing perfluoride and a heater for heating water or steam;
A catalyst layer for decomposing the perfluoride;
An acidic gas removing device for removing acidic gas in the cracked gas generated by the decomposition of the perfluoride by contacting with a calcium salt;
The flue gas, and a water or water vapor, by simultaneously heat exchanged with the decomposition gas, the flue gas, and, together with preheated water or steam, the heat exchanger and the including perfluorinated cooling the decomposition gas Chemical processing equipment.

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