JP2009034636A - Method and apparatus for treating exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating an exhaust gas which is capable of favorably suppressing a phenomenon of high-temperature corrosion of a tube-shaped wall which forms a chamber, and a phenomenon of attaching and accumulating of powder generated on an inner surface of the tube-shaped wall when decomposing by heat. <P>SOLUTION: The method of treating the exhaust gas having a process of introducing the exhaust gas into a chamber 1 for treating the exhaust gas surrounded by a tube-shaped wall 3 and decomposing the exhaust gas by heating the exhaust gas comprises covering the inner surface of the tube-like wall 3 with a gas stream by introducing a gas for forming a barrier in the chamber 1 and flowing along the inner wall of the tube-like wall 3 at the heat decomposition process time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an exhaust gas treatment method and apparatus capable of suitably performing a thermal decomposition treatment of various exhaust gases discharged during the manufacture of semiconductors and liquid crystal devices.

For example, PFC gas (Per Fluoro Carbon) in a narrow sense such as CF ₄ , C ₂ F ₆ , C ₃ F ₆ , NF ₃ , SF ₆ , CHF _3, etc. is used for etching processing in semiconductor manufacturing processes and cleaning in CVD equipment. It is used for processing and is discharged as exhaust gas. However, since these gases have a large amount of infrared absorption and cause global warming, their release into the atmosphere is regulated.

  As a means for performing exhaust gas detoxification treatment as described above, exhaust gas is introduced into an exhaust gas treatment chamber, and the exhaust gas is heated using an electrothermal heater or a member that generates heat by electromagnetic induction. Then, there is a means for heating to a high temperature and performing thermal decomposition (for example, see Patent Documents 1 and 2). According to such a thermal decomposition method, for example, compared with a combustion decomposition method in which exhaust gas is burned and decomposed into carbon dioxide, water, and halides, the equipment cost, running cost, and maintenance cost can be suppressed to a considerably low price. it can. Moreover, since generation | occurrence | production of the carbon dioxide gas as global warming gas is also suppressed, it is preferable also from the surface of environmental protection.

  However, in the prior art, there are still points to be improved as described below.

First, the exhaust gas treatment chamber has a configuration in which, for example, the periphery thereof is surrounded by a cylindrical wall such as a cylindrical shape. When the exhaust gas is introduced into the chamber and thermally decomposed, the above cylindrical shape is used. The inner surface of the wall is directly exposed to the exhaust gas and a highly corrosive decomposition product of the exhaust gas under high temperature conditions. For this reason, the inner surface of the cylindrical wall is easily corroded. More specifically, in order to suitably thermally decompose exhaust gas such as PFC gas and NF ₃ , the heating temperature is set to a considerably high temperature of, for example, about 800 to 1100 ° C. or higher than about 1300 to 1400 ° C. There is a need. When exhaust gas or a decomposition product of this exhaust gas is in direct contact with the inner surface of the cylindrical wall surrounding the chamber under such a high temperature condition, the portion is easily corroded at high temperature. For this reason, in the said prior art, it was necessary to replace | exchange parts of the cylindrical wall which forms a chamber comparatively frequently. Further, when high temperature corrosion occurs on the inner surface of the cylindrical wall, the metal sludge of the corrosion product may be mixed into the exhaust gas decomposition product. If such a situation occurs, the above-mentioned metal sludge enters into a blower or other equipment for the powder processing step in the subsequent stage, for example, and there is a problem that these equipment are damaged.

Second, some of the exhaust gas, and solidified by heating oxidative decomposition, there is to be a powder (e.g., SiF _4). In the prior art, there is also a phenomenon in which the powder generated in this way adheres to and accumulates on the inner surface of the cylindrical wall surrounding the chamber, and it is desired that such a phenomenon be suitably eliminated.

JP 11-188231 A JP 2002-153726 A

  The present invention has been conceived under the circumstances as described above, and the phenomenon that the cylindrical wall forming the chamber corrodes at a high temperature, and the powder generated during the thermal decomposition of the cylindrical wall An object of the present invention is to provide an exhaust gas treatment method and an exhaust gas treatment apparatus that can suitably suppress the phenomenon of adhesion and deposition on the inner surface.

  In order to solve the above problems, the present invention takes the following technical means.

  The exhaust gas treatment method provided by the first aspect of the present invention includes a thermal decomposition step of introducing exhaust gas into an exhaust gas treatment chamber surrounded by a cylindrical wall and heating and decomposing the exhaust gas. An exhaust gas treatment method comprising: introducing a barrier forming gas into the chamber and causing the gas to flow along the inner surface of the cylindrical wall during the pyrolysis step. The inner surface of the wall is covered with the gas flow.

  According to such a configuration, the inner surface of the cylindrical wall surrounding the periphery of the chamber is covered with the flow of the gas for forming the barrier. The degree of direct contact with the surface becomes small, and corrosion can be hardly caused in this portion. As a result, the part replacement frequency of the member having the cylindrical wall can be reduced. Further, it is possible to reduce the possibility that the metal sludge of the corrosion product on the inner surface of the cylindrical wall is mixed into the exhaust gas decomposition product. Furthermore, according to the present invention, it is also possible to suitably prevent the powder generated by pyrolysis from being deposited on the inner surface of the cylindrical wall.

  The exhaust gas treatment method provided by the second aspect of the present invention includes a thermal decomposition step in which exhaust gas is introduced into an exhaust gas treatment chamber surrounded by a cylindrical wall, and the exhaust gas is heated and decomposed. An exhaust gas treatment method having a porous shape having air permeability as the cylindrical wall and directing a gas for forming a barrier toward the cylindrical wall during the pyrolysis step By supplying, it is made to permeate | transmit the said cylindrical wall, and it is made to advance toward the said chamber from the inner surface of the said cylindrical wall.

  According to such a configuration, since the gas for forming the barrier advances from the inner surface of the porous cylindrical wall surrounding the chamber toward the inside of the chamber, the decomposition product having the corrosiveness of the exhaust gas or the exhaust gas is generated. The degree of direct contact with the inner surface of the cylindrical wall is reduced. Therefore, it is difficult to cause corrosion on the inner surface of the cylindrical wall, the frequency of parts replacement is reduced, and the problem that metal sludge or the like of the corrosion product is mixed into the exhaust gas decomposition product can be solved. Furthermore, it is also preferable to suppress the powder generated by pyrolysis from adhering to and depositing on the inner surface of the cylindrical wall.

  In a preferred embodiment of the present invention, a part of the barrier forming gas or a barrier forming gas different from the barrier forming gas is supplied to the cylindrical wall during the pyrolysis step. It introduce | transduces in the said chamber without making it permeate | transmit, it is made to flow along the inner surface of the said cylindrical wall, and the inner surface of the said cylindrical wall is covered with this gas flow.

  According to such a configuration, the gas for forming the barrier advances from the inner surface of the porous cylindrical wall into the chamber, and the gas for forming the barrier introduced into the chamber by a different route. Is obtained in synergy with the action of flowing along the inner surface of the cylindrical wall, and it is possible to more thoroughly prevent the exhaust gas or its decomposition products from coming into direct contact with the inner surface of the cylindrical wall.

  In a preferred embodiment of the present invention, the method further includes a step of heating before introducing the gas for forming the barrier into the chamber.

  According to such a configuration, the barrier forming gas is heated and then introduced into the chamber. When the gas for forming the barrier is introduced into the chamber at a low temperature, the temperature in the chamber (heating temperature of the exhaust gas) may be greatly reduced. Can be resolved. In addition, if the barrier forming gas is a dry gas by the above heating, the inner surface of the cylindrical wall is damaged due to the hydrogen radicals without generating hydrogen radicals due to high temperature decomposition of the moisture. It can also be prevented.

  In a preferred embodiment of the present invention, as the cylindrical wall, an oxide protective layer having a higher heat resistance than the base of the cylindrical wall is used on the inner surface, and the gas for forming the barrier is used. As described above, oxygen or a gas containing oxygen is used, and when the cylindrical wall is heated or generates heat, the inner surface of the cylindrical wall is oxidized to maintain the oxide protective layer. Or try to regenerate.

  According to such a configuration, the oxide protective layer excellent in heat resistance of the inner surface of the cylindrical wall is preferably maintained or regenerated, and is more preferable for preventing high temperature corrosion of the cylindrical wall.

  In a preferred embodiment of the present invention, an inert gas is used as the barrier forming gas.

  According to such a configuration, it is preferable for preventing corrosion of the inner surface of the cylindrical wall. For example, when the cylindrical wall is made of a Ni alloy-based stainless metal or Inconel alloy, high-temperature oxidation scale is often generated under a high-temperature atmosphere condition in which oxygen is present, and the consumption of the cylindrical wall tends to increase. On the other hand, if the barrier gas is an inert gas such as argon or nitrogen, such a problem is solved.

  The exhaust gas treatment apparatus provided by the third aspect of the present invention includes an exhaust gas treatment chamber having an exhaust gas inlet and an exhaust port and surrounded by a cylindrical wall, and is introduced into the chamber. And a heating means for heating and pyrolyzing the exhaust gas, and introducing a barrier-forming gas into the chamber along the inner surface of the cylindrical wall. It is characterized by having a barrier forming means to flow.

  According to such a configuration, the same effect as that obtained by the exhaust gas treatment method provided by the first aspect of the present invention can be obtained.

  In a preferred embodiment of the present invention, a lid member having the exhaust gas inlet at a substantially central portion is provided at the upper part of the chamber, and the exhaust gas outlet is provided at the lower part of the chamber. The lid member is provided so as to form an annular gap with the inner surface of the upper portion of the cylindrical wall, and the gas for forming the barrier is formed from the outside of the chamber. It is configured to flow along the inner surface of the cylindrical wall by being introduced into the gap and progressing downward from almost all the circumference of the gap.

  According to such a configuration, it is possible to appropriately realize the barrier forming gas to flow along substantially the entire inner surface of the cylindrical wall with a simple configuration.

  An exhaust gas treatment apparatus provided by the fourth aspect of the present invention includes an exhaust gas treatment chamber having an exhaust gas inlet and an exhaust port and surrounded by a cylindrical wall, and introduced into the chamber. An exhaust gas treatment apparatus comprising: heating means for heating and pyrolyzing the exhaust gas, wherein the cylindrical wall has a porous shape having air permeability, and the gas for forming a barrier is Barrier forming means is provided, which is supplied toward the cylindrical wall so as to permeate the cylindrical wall and advance from the inner surface of the cylindrical wall into the chamber.

  According to such a configuration, the same effect as that obtained by the exhaust gas treatment method provided by the second aspect of the present invention can be obtained.

  In a preferred embodiment of the present invention, a part of the barrier forming gas or a barrier forming gas different from the barrier forming gas does not pass through the cylindrical wall. It is set as the structure which can be introduced in and can flow along the inner surface of the said cylindrical wall.

  According to such a configuration, the gas for forming the barrier advances from the inner surface of the porous cylindrical wall into the chamber, and the gas for forming the barrier introduced into the chamber by a different route. Is obtained in synergy with the action of flowing along the inner surface of the cylindrical wall, and it is possible to more thoroughly prevent the exhaust gas or its decomposition products from coming into direct contact with the inner surface of the cylindrical wall.

  In a preferred embodiment of the present invention, the gas for forming the barrier is preheated by the heating means or by a heating means different from the heating means before being introduced into the chamber. Has been.

  According to such a configuration, the barrier forming gas can be heated to a high temperature and then introduced into the chamber. Therefore, it is possible to prevent a problem that the temperature in the chamber is greatly lowered due to the introduction of the barrier forming gas into the chamber.

  In a preferred embodiment of the present invention, an electromagnetic induction coil and a gas that is provided so as to surround the cylindrical wall in a single layer or a plurality of layers and that guides the barrier forming gas from the outside into the chamber. One or a plurality of auxiliary cylindrical walls that form a flow path and can generate heat by driving the electromagnetic induction coil, and the gas flow path is generated when the auxiliary cylindrical wall generates heat. The gas for forming the barrier that passes through is heated, and the exhaust gas introduced into the chamber is heated.

  According to such a configuration, both the exhaust gas and the barrier forming gas can be heated reasonably by simple means.

  In a preferred embodiment of the present invention, a flow rate adjusting valve or a blower capable of adjusting the amount of air flowing from the outside into the gas flow path is provided, and the auxiliary cylinder is controlled by the flow rate adjusting valve or the blower. The exothermic temperature of the wall-like wall, the exhaust gas decomposition temperature, and the amount of gas for forming a barrier into the chamber can be controlled.

  In a preferred embodiment of the present invention, a heating auxiliary heating element disposed in the chamber, a porous member covering the heating element, and a gas in a space surrounded by the porous member. Gas introduced to the space from the gas introducing means and permeates the porous member and flows out from various places on the outer surface toward the chamber. Thus, a barrier is formed.

  According to such a configuration, exhaust gas heating using the heating auxiliary heating element is also possible, so that the exhaust gas heating temperature can be further increased. Further, since the heating element is covered with a porous member, the heating element itself is prevented from being in direct contact with the exhaust gas and protected. In addition, since a barrier is formed on the outer surface of the porous member by the flow of gas that has passed through the porous member, the outer surface of the porous member causes high-temperature corrosion, or the It is also possible to appropriately suppress a large amount of exhaust gas decomposition products from adhering to the outer surface.

  Other features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of an exhaust gas treatment apparatus according to the present invention. An exhaust gas treatment apparatus A1 of the present embodiment includes an exhaust gas treatment chamber 1, a cylindrical wall 3 surrounding the chamber 1, an auxiliary cylindrical wall 6 surrounding the cylindrical wall 3, an electromagnetic induction coil 2, and an external Are provided with an air drying device 70 and a blower 71 for heating and drying the air to be supplied into the chamber 1. In the present embodiment, air heated and dried by the air drying device 70 is used as the “barrier forming gas” in the present invention.

  The electromagnetic induction coil 2 is configured using, for example, a copper pipe through which cooling water flows, and is disposed in the housing 20. The housing 20 has a substantially cylindrical shape made of, for example, a heat insulating material, and surrounds the cylindrical wall 3 and the auxiliary cylindrical wall 6. A high-frequency power source (not shown) is connected to the electromagnetic induction coil 2 by wiring, and when a high-frequency current flows through the electromagnetic induction coil 2, the cylindrical wall 3 generates heat due to the electromagnetic induction action. The internal space of the cylindrical wall 3 is the chamber 1.

The cylindrical wall 3 is configured using, for example, a cylindrical member, and the lower end portion thereof is supported by the lower member 43b mounted on the flange 12c of the base tubular body 12, and the vertical direction (substantially vertical direction). ) In a standing position. The material of the cylindrical wall 3 is, for example, an Fe—Cr—Al alloy (Cr: 5 to 25%, Al: 2 to 8%), or an Fe—Cr—Co—Al alloy in which Co is added thereto. Aluminum alloy. Although not shown in the drawing, an alumina (Al ₂ O ₃ ) layer as an oxidation protection layer is formed on the entire inner peripheral surface of the cylindrical wall 3. This alumina layer is formed by oxidizing the surface layer portion of the cylindrical wall 3, and has better heat resistance than the base of the cylindrical wall 3.

An exhaust port 10 and an exhaust port 11 for exhaust gas are formed in the upper and lower portions of the chamber 1. More specifically, a lid member 40 is disposed on the upper portion of the chamber 1, and a hole portion penetrating vertically is provided at a substantially central portion of the lid member 40. This hole is an introduction port 10 for exhaust gas, and the exhaust gas enters the chamber 1 through the introduction port 10 and proceeds downward. On the upper part of the lid member 40, a member 41 having a plurality of pipe connecting portions J1 to J5 for connecting the tubular bodies is provided. The piping parts J1 to J3 are made of, for example, process exhaust gas such as silane gas and TEOS sent from a semiconductor facility (not shown), cleaning exhaust gas of PFC gas such as NF ₃ and C ₂ F ₆ , or SF ₆ and ClF ₃ . These are for receiving the etching exhaust gas, and these are all introduced into the chamber 1 from the inlet 10.

  Air for mixing with the process exhaust gas is supplied to the pipe portion J4. The air is supplied from, for example, a pipe portion 72a connected to the rear stage of the blower 71. By controlling the valves V1 and V2, it is possible to select between air that has passed through the air drying device 70 and air that has not passed. is there. Water vapor for mixing with the cleaning exhaust gas or the etching exhaust gas is supplied to the pipe portion J5. As this water vapor, the water cooled through the copper pipe of the electromagnetic induction coil 2 or the water-cooled pipes 44a and 44b provided for the purpose of cooling the high temperature portion of the exhaust gas treatment apparatus A1. It can be generated using water heated through circulation. A part of the inlet 10 is a multi-pipe structure 10a through which the exhaust gas, air, and water vapor can be individually passed.

  The lower part of the inlet 10 and the vicinity thereof are formed in a multistage shape in which the opening diameter is gradually increased on the lower side than the upper side, and the exhaust gas discharged downward toward the chamber 1 is large. Spreading at an angle is suppressed. The member constituting the exhaust gas path from the piping parts J1 to J5 to the inlet 10 is preferably made of a material having excellent corrosion resistance such as stainless steel, and more preferably, the surface thereof is coated with fluorine. It is used. Among the exhaust gas treatment apparatus A1, other members not particularly specified are also made of a material excellent in corrosion resistance and heat resistance. Specific examples include corrosion-resistant stainless steel, other heat-resistant metals, ceramics, and high-density alumina fibers.

  The exhaust port 11 for exhaust gas is connected to the internal space of the base tube 12, and the exhaust gas decomposition treatment component is discharged downward from the lower opening 12 a of the base tube 12. Although not shown in the drawing, a water reservoir is provided below the lower opening 12a, and the exhaust gas is cooled by being passed through the water in the water reservoir, and depending on the components, To be caught. In addition, a blower and an ejector intake pipe (both not shown) are connected to the lower opening 12a. When the exhaust gas is introduced into the chamber 1, the blower is driven and negative pressure is applied to the chamber 1. This is done by the action that occurs. In the present embodiment, the air heated and dried by the air drying device 70 is introduced into the chamber 1 using the blower 71 as described later, but the present invention is not limited to this. In the present invention, the blower 71 may be omitted, and the air introduction described above may be performed by the negative pressure of the blower connected to the lower opening 12a.

  The inner peripheral surface of the base tube body 12 has a tapered shape in which the inner diameter gradually decreases toward the lower side, and a water supply pipe 13 for supplying cooling water to the inside of the base tube body 12 is connected to the upper portion of the base tube body 12. ing. The water supplied from the water supply pipe 13 to the inside of the base tube body 12 becomes a swirling flow and proceeds from the upper part to the lower part of the inner peripheral surface of the base tube body 12. In addition to cooling the base tube body 12, the swirling flow also exerts an effect of washing away powder generated by thermal decomposition of the exhaust gas when it falls on the inner surface of the base tube body 12.

  The auxiliary cylindrical wall 6 is configured using, for example, a ceramic cylindrical body, and is disposed so as to surround the cylindrical wall 3, and an air flow path 46 is formed between the auxiliary cylindrical wall 6 and the cylindrical wall 3. . The lower member 43b is formed with an air passage 45 that is annular in plan view and communicates with the air passage 46. The air flow path 45 is connected to a pipe portion 72b on the outlet side of the air drying device 70. The air heated and dried by the air drying device 70 is supplied to the air flow channel 45, and then the air flow The air passage 46 is configured to flow from the entire circumference of the passage 45. A downward convex portion 40 a is formed on the lower surface portion of the lid member 40, and an annular gap portion 47 is formed between the outer peripheral surface of the convex portion 40 a and the upper inner peripheral surface of the cylindrical wall 3. It is formed extending in the vertical direction. The air that has traveled upward through the air flow path 46 flows into the gap 47 and then travels downward along the inner peripheral surface of the cylindrical wall 3 in the chamber 1.

  Next, a method for thermally decomposing exhaust gas using the above-described exhaust gas treatment apparatus A1 will be described.

  In order to perform the pyrolysis treatment of the exhaust gas, first, a high-frequency current is passed through the electromagnetic induction coil 2 to heat the cylindrical wall 3 by electromagnetic induction heating, and the air heated and dried by the air drying device 70 is sent from the pipe portion 72b to the air. It supplies to the flow paths 45 and 46, and introduces it into the chamber 1 from the clearance gap 47 of the upper part. In such a state, when exhaust gas is introduced into the chamber 1 from the inlet 10, the exhaust gas is heated to a high temperature and thermally decomposed. The air traveling downward from the gap 47 flows along the inner peripheral surface of the cylindrical wall 3, and this air flow indicates that the exhaust gas and the decomposed components of the exhaust gas contact the inner peripheral surface of the cylindrical wall 3. It becomes a barrier to suppress. For this reason, it becomes difficult for the inner peripheral surface of the cylindrical wall 3 to corrode. Further, some exhaust gases are individualized by thermal decomposition and become powder, but such powder is prevented from adhering to and depositing on the inner peripheral surface of the cylindrical wall 3 by the air flow. . Therefore, durability of the cylindrical wall 3 is improved, and it is not necessary to frequently replace the cylindrical wall 3. The replacement work of the cylindrical wall 3 can be performed by removing the cover member 40 and forming an opening for maintenance above the cylindrical wall 3.

  The cylindrical wall 3 has an alumina layer that has better heat resistance than the base of the cylindrical wall 3 due to oxidation of the inner peripheral surface thereof, so that the inner peripheral surface is less susceptible to corrosion. It can be. Even if the alumina layer is damaged, air is continuously supplied on the inner peripheral surface of the cylindrical wall 3 under a high temperature condition. The alumina layer is regenerated. Therefore, the durability of the cylindrical wall 3 is further enhanced.

  The flow rate of the dry air flowing along the inner peripheral surface of the cylindrical wall 3 can be appropriately changed according to the opening degree of the valves V1 and V2 and the driving speed of the blower 71. Therefore, it is possible to form an air flow suitable for appropriately suppressing the exhaust gas and the decomposition component of the exhaust gas from contacting the inner surface of the cylindrical wall 3. In addition, since the total amount of air introduced into the chamber 1 can be adjusted, the mixing ratio of the exhaust gas and air can be set to a ratio suitable for thermal decomposition according to the type of the exhaust gas.

  The air introduced into the chamber 1 through the gap 47 is preliminarily heated and dried by the air drying device 70 and is further heated by the cylindrical wall 3 when passing through the air flow path 46. For this reason, when the air is introduced into the chamber 1, there is no problem that the temperature in the chamber 1 is greatly reduced. Further, since the air is dry air that does not contain moisture, generation of hydrogen radicals due to high-temperature decomposition of moisture on the surface of the cylindrical wall 3 is eliminated, and the effect of extending the life of the alumina layer is also obtained. It is done. In the case where the air can be heated to a sufficient temperature when the air passes through the air flow path 46, the air drying device 70 may be omitted. Further, when air passes through the air flow path 46, as one means for increasing the heating efficiency, a spiral coil is disposed in the air flow path 46, and the air passes through the air flow path 46 along the spiral coil. You may make it advance in a spiral. In this way, the air heating time can be increased, and the air introduced into the chamber 1 can be heated to a higher temperature. If the spiral coil generates heat by electromagnetic induction, the temperature of the air can be further increased.

  2 to 7 show other embodiments of the present invention. In these drawings, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as in the above embodiment.

  In the exhaust gas treatment apparatus A2 shown in FIG. 2, the cylindrical wall 3A surrounding the chamber 1 has a double wall structure in which an inner cylinder 30 made of ceramic and an outer cylinder 31 fitted on the inner cylinder 30 are combined. ing. The outer cylinder 31 is made of an aluminum alloy having an alumina layer formed on the surface thereof, for example, similarly to the cylindrical wall 3 of the embodiment. The inner cylinder 30 is longer in the vertical direction than the outer cylinder 31, and covers the inner surface side of the outer cylinder 30 so that the outer cylinder 31 does not directly contact the exhaust gas or the decomposed components of the exhaust gas. The auxiliary cylindrical wall 6A is made of a material that can generate electromagnetic induction heat by driving the electromagnetic induction coil 2 (for example, the same material as the outer cylinder 31). When the auxiliary cylindrical wall 6A generates heat, the housing 20 becomes high temperature and its radiant heat increases. As a means for preventing this, heat exchange is performed between the auxiliary cylindrical wall 6A and the electromagnetic induction coil 2. A coil 29 is provided.

  According to this embodiment, since the outer cylinder 31 and the auxiliary cylindrical wall 6A generate heat by electromagnetic induction, the heating temperature of the exhaust gas and the heating temperature of the air passing through the air flow path 46 can be increased. it can. Moreover, since the outer peripheral surface of the outer cylinder 31 is covered by the inner cylinder 30 and contact with the exhaust gas is prevented, corrosion of the outer cylinder 31 is more preferably prevented. About the inner cylinder 30, since the contact with exhaust gas and its decomposition product is suppressed by the effect | action of the airflow which flows downward from the clearance gap 47, the inner peripheral surface becomes difficult to receive a damage, and adhesion of powder Deposition is unlikely to occur.

  In the exhaust gas treatment apparatus A3 shown in FIG. 3, the cylindrical wall 3B surrounding the chamber 1 is configured using a porous ceramic cylindrical body having many fine holes. Two auxiliary cylindrical walls 6B and 6C that generate heat by electromagnetic induction are provided around the outer periphery of the cylindrical wall 3B, and the dry air supplied to the air flow path 45 is formed between them. It is configured to flow through the air flow path 46a being heated and flow to the air flow path 46b formed between the auxiliary cylindrical wall 6C and the cylindrical wall 3B. When the dry air flows into the air flow path 46b, the air passes through the fine holes of the cylindrical wall 3B and flows into the chamber 1.

  The chamber 1 is provided with an inner cylinder portion 81 that generates heat by electromagnetic induction and an outer cylinder portion 82 that covers the inner cylinder portion 81 as means for assisting heating of the exhaust gas. A pipe part 83 is connected to the lower end part of the inner cylinder part 81, and dry air can be supplied to the pipe part 83 from the outside. The outer cylinder part 82 is made of a porous ceramic like the cylindrical wall 3B, and its upper end is closed. When dry air is supplied into the inner cylinder part 81 via the pipe part 83, the dry air flows into the gap between the inner cylinder part 81 and the outer cylinder part 82, and then substantially the entire area of the outer cylinder part 82. In FIG. 3, the gas passes through a fine hole and flows into the chamber 1.

  According to the present embodiment, the heated and dried air that has flowed into the air drying path 46b passes through the porous cylindrical wall 3B and travels into the chamber 1, so that it is not near the inner peripheral surface of the cylindrical wall 3B. A barrier that prevents the exhaust gas from proceeding toward the inner peripheral surface of the cylindrical wall 3B is formed. For this reason, it can suppress that exhaust gas and the decomposition | disassembly component of exhaust gas contact the inner peripheral surface of the cylindrical wall 3B, and can aim at protection of the cylindrical wall 3, and prevention of adhesion deposit of a decomposition product. Moreover, since the exhaust gas is heated not only by the heat generation of the auxiliary cylindrical walls 6B and 6C but also by the heat generation of the inner cylinder portion 81, the heating temperature of the exhaust gas can be further increased. In the chamber 1, the portion where the inner cylinder portion 81 is provided is in a state in which the exhaust gas flow passage area is narrowed, so that intensive high-temperature heat treatment can be performed in this portion. Since heated dry air flows out from the surface of the porous outer cylinder part 81 into the chamber 1, there is little possibility that exhaust gas and its decomposition components are in direct contact with the surface of the outer cylinder part 82. Therefore, the durable life of the outer cylinder part 82 can also be lengthened. Of course, since the inner cylinder part 81 is covered with the outer cylinder part 82 and contact with exhaust gas is prevented, the durable life of the inner cylinder part 81 can be extended.

  In the exhaust gas treatment apparatus A4 shown in FIGS. 4 and 5, an annular air channel 45 is formed in the upper member 43a, and dry air can be supplied to this portion from the outside via a pipe 72b. In addition, auxiliary cylindrical walls 6D to 6F are provided around a porous ceramic cylindrical wall 3B, and a plurality of air flow paths 46c to 46e are formed therebetween. Among the auxiliary cylindrical walls 6D to 6F, at least the auxiliary cylindrical wall 6D located at the innermost circumference can generate heat. The dry air supplied to the air flow path 45 sequentially passes through the plurality of air flow paths 46c and 46d and flows into the air flow path 46e, and in the process of flowing into the air flow path 46e, a porous cylindrical wall It passes through 3B and proceeds into the chamber 1. Also in the present embodiment, since the heated and dried air travels from the inner peripheral surface of the porous cylindrical wall 3B toward the chamber 1, the cylindrical wall 3B is damaged by the exhaust gas and decomposition products of the exhaust gas. Is appropriately prevented.

  In the present embodiment, the upper portion of the cylindrical wall 3B is fitted into the groove portion of the lid member 40, and only heated air that has flowed into the air flow path 46c permeates the cylindrical wall 3B and is chambered. 1 to flow into. However, in this invention, it can replace with such a structure and can also be set as a structure as shown in FIG. 6 or FIG.

  In the configuration shown in FIG. 6, a plurality of holes 39 are formed in the upper part of the cylindrical wall 3 </ b> B, and a part of the heated and dried air that has reached above the air flow path 46 d It passes through the gap 47 and travels downward from the gap 47. In the configuration shown in FIG. 7, a gap 38 is formed between the upper part of the cylindrical wall 3B and the downward surface of the lid member 40, and a part of the heated and dried air that has reached the upper side of the air flow path 46d is It passes through the gap 38, flows into the gap 47, and proceeds downward.

  According to the embodiment shown in FIGS. 6 and 7, the heated and dried air that has flowed into the air flow path 46 e passes through the porous cylindrical wall 3 </ b> B and proceeds into the chamber 1, and the heat that has flowed into the gap 47. The dry air travels downward along the inner peripheral surface of the cylindrical wall 3B. Therefore, the barrier of the heated and dried air covering the inner peripheral surface of the cylindrical wall 3B becomes high density, and it is more preferable to prevent the exhaust gas and its decomposition components from coming into contact with the inner peripheral surface of the cylindrical wall 3B.

  The present invention is not limited to the contents of the above-described embodiment. As the gas for forming a barrier referred to in the present invention, various other gases can be used instead of air or an inert gas. The cylindrical wall forming the chamber is not limited to the Al alloy described above. For example, a sintered body such as titanium diboride or zirconium diboride having high induction heating efficiency or melting point can be used. When the cylindrical wall is configured using such a sintered body, the temperature can be further increased, and the amount of exhaust gas treatment can be increased. As a result, the entire apparatus can be reduced in size. In the present invention, the specific type of exhaust gas to be treated is not limited. As the heating method, it is preferable to adopt an electromagnetic induction coil method, but other heating means such as an electric heater can be used instead.

It is sectional drawing which shows an example of the waste gas processing apparatus which concerns on this invention. It is sectional drawing which shows the other example of the waste gas processing apparatus which concerns on this invention. It is sectional drawing which shows the other example of the waste gas processing apparatus which concerns on this invention. It is sectional drawing which shows the other example of the waste gas processing apparatus which concerns on this invention. It is the B section enlarged view of FIG. It is principal part sectional drawing which shows the other example of the waste gas processing apparatus which concerns on this invention. It is principal part sectional drawing which shows the other example of the waste gas processing apparatus which concerns on this invention.

Explanation of symbols

A1-4 Exhaust gas treatment apparatus 1 Chamber 2 Electromagnetic induction coil 3, 3A, 3B Cylindrical wall (surrounding chamber)
6, 6 </ b> A to 6 </ b> E Auxiliary cylindrical wall 6 Auxiliary exothermic heating element 10 Inlet 11 Ejector 40 Lid member 45 Air channel 46, 46 a to 46 e Air channel 47 Gap

Claims (14)

An exhaust gas treatment method comprising a thermal decomposition step of introducing exhaust gas into an exhaust gas treatment chamber surrounded by a cylindrical wall and heating and decomposing the exhaust gas,
In the pyrolysis step, by introducing a gas for forming a barrier into the chamber and flowing along the inner surface of the cylindrical wall, the inner surface of the cylindrical wall is covered with the gas flow. An exhaust gas treatment method that is characterized. An exhaust gas treatment method comprising a thermal decomposition step of introducing exhaust gas into an exhaust gas treatment chamber surrounded by a cylindrical wall and heating and decomposing the exhaust gas,
As the cylindrical wall, use a porous one having air permeability,
In the pyrolysis step, a barrier forming gas is supplied toward the cylindrical wall so as to permeate the cylindrical wall and advance from the inner surface of the cylindrical wall into the chamber. Exhaust gas treatment method.   During the pyrolysis step, a part of the barrier forming gas or a barrier forming gas different from the barrier forming gas is introduced into the chamber without permeating the cylindrical wall. The exhaust gas treatment method according to claim 2, wherein the exhaust gas is caused to flow along the inner surface of the cylindrical wall, and the inner surface of the cylindrical wall is covered with the gas flow.   The exhaust gas treatment method according to any one of claims 1 to 3, further comprising a step of heating before introducing the gas for forming the barrier into the chamber. As the cylindrical wall, an oxide protective layer having higher heat resistance than that of the cylindrical wall substrate is used on the inner surface, and as the gas for forming the barrier, oxygen or a gas containing oxygen is used. use,
5. When the cylindrical wall is heated or generating heat, the inner surface of the cylindrical wall is oxidized to maintain or regenerate the oxide protective layer. The exhaust gas treatment method according to 1.   The exhaust gas treatment method according to claim 1, wherein an inert gas is used as the barrier forming gas. An exhaust gas treatment chamber having an exhaust gas inlet and an exhaust port and surrounded by a cylindrical wall;
Heating means for heating and thermally decomposing the exhaust gas introduced into the chamber;
An exhaust gas treatment apparatus comprising:
An exhaust gas treatment apparatus comprising barrier forming means for introducing a gas for forming a barrier into the chamber and causing the gas to flow along the inner surface of the cylindrical wall. The upper part of the chamber is provided with a lid member having the exhaust gas inlet in the substantially central portion, and the lower part of the chamber is provided with the exhaust gas outlet.
The lid member is provided so as to form an annular space between the upper inner surface of the cylindrical wall,
The gas for forming the barrier is introduced into the annular gap from the outside of the chamber, and flows downward along substantially the entire circumference of the gap to flow along the inner surface of the cylindrical wall. The exhaust gas treatment apparatus according to claim 7, configured as described above. An exhaust gas treatment chamber having an exhaust gas inlet and an exhaust port and surrounded by a cylindrical wall;
Heating means for heating and thermally decomposing the exhaust gas introduced into the chamber;
An exhaust gas treatment apparatus comprising:
The cylindrical wall is a porous shape having air permeability,
Barrier forming means is provided for supplying gas for barrier formation toward the cylindrical wall so as to permeate the cylindrical wall and advance from the inner surface of the cylindrical wall into the chamber. Exhaust gas treatment equipment.   A part of the gas for forming the barrier or a gas for forming a barrier different from the gas for forming the barrier is introduced into the chamber without passing through the cylindrical wall, and the inner surface of the cylindrical wall The exhaust gas treatment apparatus according to claim 9, wherein the exhaust gas treatment apparatus is configured to be capable of flowing along a vertical axis.   The gas for barrier formation is configured to be preheated by the heating means or by a heating means different from the heating means before being introduced into the chamber. The exhaust gas treatment apparatus according to any one of the above. A coil for electromagnetic induction;
Drives the electromagnetic induction coil, which is provided so as to surround the cylindrical wall in a single layer or a plurality of layers, and forms a gas flow path for guiding the gas for forming the barrier from the outside into the chamber. One or more auxiliary cylindrical walls capable of generating heat by,
The structure is such that when the auxiliary cylindrical wall generates heat, the gas for forming a barrier passing through the gas flow path is heated, and the exhaust gas introduced into the chamber is heated. 11. An exhaust gas treatment apparatus according to 11. It has a flow rate adjustment valve or blower that can adjust the amount of air flowing from the outside to the gas flow path,
The heat generation temperature of the auxiliary cylindrical wall, the exhaust gas decomposition temperature, and the amount of gas for forming a barrier into the chamber can be controlled by controlling the flow rate adjusting valve or blower. The exhaust gas treatment apparatus described in 1. A heating auxiliary heating element disposed in the chamber;
A porous member covering the heating element;
Gas introducing means for introducing gas into the space surrounded by the porous member,
The gas introduced into the space from the gas introduction means is configured to pass through the porous member and flow out from various places on the outer surface toward the chamber to form a barrier. Item 14. The exhaust gas treatment apparatus according to any one of Items 7 to 13.

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