JP2011098306A - Volatile organic compound treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a miniaturizable volatile organic compound treatment apparatus with low running cost, high safety and high treating efficiency. <P>SOLUTION: The volatile organic compound treatment apparatus 1 is provided with: a conductive heat generating body 20 with a communication hole for passing gas therethrough formed therein; electrodes 21a, 21b energizing the conductive heat generating body; a heating part 2 heating gas passing through the communication hole by heat generated by the conductive heat generating body by energizing; a catalyst body lowering the oxidative decomposition temperature of a volatile organic compound; and a catalyst part provided downstream of the gas passage from the heating part and oxidatively decomposing the volatile organic compound contained in the gas heated by the heating part. The heating part includes: a metal layer 23 integrally laminated on an end face of the conductive heat generating body of the electrode side by solidifying a molten metal; and a steel wool layer 22 as a conductive elastic body set between the metal layer and electrode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an apparatus for treating volatile organic compounds, and is particularly used for decomposing volatile organic compounds in gases discharged from factories and offices and releasing treated gases into the atmosphere. The present invention relates to a volatile organic compound processing apparatus.

  Volatile organic compounds (VOCs) are one of the causative substances of suspended particulate matter and photochemical oxidants. Factories and offices over a certain scale are subject to VOC emission regulations, and are not subject to regulation. Business establishments are also required to voluntarily reduce VOC emissions. There are statistics that the Tokai region where the applicants are located has more VOC emissions than other regions, and the proportion of small and medium-sized establishments is also high. Therefore, in order to advance voluntary efforts to suppress VOC emissions at small and medium-sized business establishments, a small and low running cost VOC processing apparatus that is easy to introduce at small and medium-sized business establishments is desired.

  Conventional VOC treatment apparatuses are roughly classified into apparatuses using an adsorption method, a chemical solution absorption method, a biodegradation method, a plasma decomposition method, and a combustion oxidation method (direct combustion type, heat storage combustion type, catalytic combustion type). Among them, in the combustion oxidation method, an apparatus using a burner as a heating means (for example, see Patent Document 1) and an apparatus using an electric heater (for example, see Patent Document 2) are generally used.

  However, an adsorption method or chemical solution absorption method that requires replacement of adsorbents or chemicals and a running cost, a biodegradation method that requires labor and expense for biological maintenance, and a device that uses a large and expensive plasma decomposition method Was not suitable for small and medium-sized establishments. Further, in an apparatus using a burner as a heating means, there is a risk of flammable VOCs being ignited. In addition, an apparatus using an electric heater has a problem that heat efficiency is poor and heating takes time.

  Therefore, in view of the above circumstances, the applicants are proceeding with the development and proposal of a volatile organic compound processing apparatus capable of downsizing, low running cost, high safety, and high processing efficiency (see above). Since the patent application concerning the proposed invention is before publication of the application, it does not correspond to a known document). The present invention relates to the improvement of the above-mentioned proposed volatile organic compound processing apparatus, and an object thereof is to further increase the processing efficiency.

  That is, an object of the present invention is to provide a volatile organic compound processing apparatus that can be miniaturized, has a low running cost, has high safety, and has high processing efficiency.

  In order to solve the above-mentioned problems, the volatile organic compound processing apparatus according to the present invention includes: “a conductive heating element having a communicating hole portion through which a gas flows, and an electrode for energizing the conductive heating element. A heating part that heats the gas flowing through the communication hole part by the heat generation of the conductive heating element by energization, and a catalyst body that lowers the oxidative decomposition temperature of the volatile organic compound, and the gas circulation from the heating part And a catalyst unit that oxidatively decomposes volatile organic compounds contained in the gas heated by the heating unit, and the heating unit generates the conductive heat generated on the electrode side by solidification of molten metal. A metal layer integrated and laminated on an end surface of the body, and a conductive elastic layer provided between the metal layer and the electrode.

  As the “conductive heating element”, conductive ceramics, semiconductor ceramics, and metals can be used.

  The “communication hole portion through which the gas flows” includes, for example, a through hole provided in the conductive heating element, continuous pores when the conductive heating element has a porous structure, and a conductive heating element having a honeycomb structure as described later. It can be constituted by a cell in the case of having it.

  “Volatile organic compounds” (hereinafter, sometimes simply referred to as “VOC”) are organic compounds that are gaseous when discharged or scattered into the atmosphere and are responsible for the formation of suspended particulate matter and oxidants. Substances specified by a Cabinet Order are excluded as substances that cannot be used, and examples include toluene, xylene, dichloromethane, ethylbenzene, benzene, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, isopropyl alcohol, ethyl acetate, and butyl acetate. In particular, toluene and xylene are frequently used as solvents in factories and offices related to printing and painting, and have large emissions.

  Catalysts for “catalysts that lower the oxidative decomposition temperature of volatile organic compounds” include metal catalysts such as platinum, palladium, rhodium, gold, iridium, ruthenium, cerium oxide, zirconium oxide, titanium oxide, tin oxide, and oxidation. Metal oxide catalysts such as manganese and tantalum oxide can be used. Alternatively, a plurality of metal catalysts, a plurality of metal oxide catalysts, or a composite catalyst in which a metal catalyst and a metal oxide catalyst are combined can be used. In addition, although the oxidative decomposition temperature of VOC is 650-800 degreeC, it can be oxidatively decomposed at 200-400 degreeC by the effect | action of said catalyst.

  The structure of the “catalyst body” includes a structure in which a catalyst is supported on a porous body through which gas can flow, a structure in which continuous pores and through holes are provided in the catalyst itself, and gas is circulated, and a tubular shape and a tubular shape in which gas is circulated A configuration in which the catalyst is filled while leaving a gap through which gas can flow can be exemplified.

  The “catalyst part” is “provided on the downstream side of the gas flow from the heating part”, and the heating part and the catalyst part are separate configurations.

  “The metal layer integrated and laminated on the end face of the conductive heating element by solidification of the molten metal” is, for example, the metal is sprayed on the end face of the conductive heating element, or the end of the conductive heating element is melted. After the metal is partially immersed, the metal can be formed by cooling.

  The “conductive elastic body” in the “conductive elastic layer” includes steel wool, magnesium ribbon and gold ribbon processed metal material, carbon fiber, coiled and thin metal bent into a corrugated shape It is possible to use a conductive material having high elasticity, such as a wire rod.

  In the present invention having the above-described configuration, an untreated gas containing VOC discharged from a factory or business place is circulated through the communicating hole of the conductive heating element while the conductive heating element is heated by energization. The untreated gas can be heated. Here, a metal layer is formed on the end face of the conductive heating element on the electrode side, and a conductive elastic layer is provided between the metal layer and the electrode. Therefore, the electrical connection between the metal layer and the electrode becomes good due to the elasticity of the conductive elastic layer. The metal layer is formed by solidification of the molten metal, and is integrated with the conductive heating element at the end face of the conductive heating element. In other words, the end face of the conductive heating element on the electrode side is in a state where a metal film is formed as a whole. This makes it easy to energize the entire conductive heating element via the metal layer. Therefore, according to the present invention, the conductive heating element can be energized well between the electrodes via the conductive elastic layer and the metal layer, and the conductive heating element can be efficiently heated.

  And the untreated gas heated by the heating part provided with an electroconductive heat generating body flows in into the catalyst part provided in the downstream, and receives the effect | action of a catalyst. Therefore, in the heating section, the temperature of the untreated gas is raised to the oxidative decomposition temperature of VOC in the presence of the catalyst, and then introduced into the catalyst section to decompose VOC at a lower temperature than in the case of oxidative decomposition by direct combustion. be able to. And in this invention, since the structure which distribute | circulates gas self-heats by electricity supply, unlike the case where it heats from the outside with external heat sources, such as a heater and a burner, there exists a possibility that it may become extremely high by local heating and may be damaged. In addition, the risk of cracking due to a large temperature gradient is reduced. Moreover, by being a self-heating type, electric energy can be efficiently used for heating the untreated gas.

  Here, it can also be assumed that the catalyst body has a structure in which the catalyst is supported in the communicating hole portion of the conductive heating element. However, in this case, the untreated gas passes through the catalyst body before it is sufficiently heated, and there is a risk that the oxidative decomposition of VOC will be insufficient. On the other hand, in the present invention, the heating unit and the catalyst unit are configured separately, and the temperature of the untreated gas can be sufficiently increased in advance in the heating unit and then introduced into the downstream catalyst unit. It is possible to sufficiently oxidatively decompose VOC at a low temperature.

  In addition, conventionally, when the gas is heated by an external heat source such as a heater or a burner and the VOC is oxidatively decomposed by direct combustion, the gas is stored in the combustion chamber and heated to the combustion temperature. A certain amount of space is required, and it is difficult to downsize the entire apparatus. On the other hand, in the present invention, in order to heat the gas, it is sufficient to continuously pass the gas through the conductive heating element in which the communication hole portion is formed. Therefore, the entire apparatus can be reduced in size. is there.

  Moreover, in this invention, since there is no possibility of igniting VOC like the conventional apparatus which uses a burner, it is a highly safe apparatus. In addition, there are no parts that need to be replaced regularly as in the conventional device using the adsorption method or chemical solution absorption method, and there is no problem in the maintenance of organisms as in the conventional device using the biodegradation method. Is inexpensive and easy to handle.

  The volatile organic compound processing apparatus according to the present invention may be “the conductive elastic body layer is formed of stainless steel wool” in addition to the above configuration.

  In this invention of the said structure, an electroconductive elastic body is a steel wool, Therefore An electrode and a metal layer can be electrically connected in many contact points.

  Further, since the untreated gas containing air flows in the heating section in a heated state, the steel wool of the conductive elastic layer is oxidized, and good current conduction through the conductive elastic layer is hindered by the oxide film. In addition, in the present invention, stainless steel wool is used because there is a possibility that sparks may be generated when the insulation by the oxide film is broken. Stainless steel has a thin passive film on the surface due to oxidation of contained chromium, and is not easily oxidized. This reduces the possibility that good energization through the conductive elastic body layer will be hindered, can efficiently heat the untreated gas, and reduces the possibility of locally high temperatures due to the occurrence of sparks, The durability of the heating part can be increased.

  The volatile organic compound processing apparatus according to the present invention has the above-described configuration, wherein “the conductive heating element is formed of a conductive ceramic sintered body and includes a plurality of partition walls extending in a single axial direction. Formed of a plurality of honeycomb structures having a honeycomb structure including a plurality of partitioned cells, and a conductive ceramic sintered body integrated with the honeycomb structures, and the adjacent honeycomb structures are arranged in the axial direction. A connecting portion connected in a direction orthogonal to each other ”.

  The partition of the “honeycomb structure” may be porous or dense, but if it is porous, fine dust or particulate matter contained in the untreated gas is formed by pores opened in the partition. It is excellent in filtering action that is collected and removed, and is suitable.

  The “conductive ceramic sintered body” forming the honeycomb structure part and the “conductive ceramic sintered body” forming the connecting part may be the same or different in type and composition of ceramics. Although it is good, if the thermal expansion coefficient is the same or similar, it is desirable that thermal stress hardly occurs with heating.

  The “cell” in the honeycomb structure portion corresponds to the “communication hole portion”. In a ceramic sintered body having a honeycomb structure, it is possible to arrange a large number of cells whose shape and size are controlled, so that the flow resistance of untreated gas can be suppressed by flowing gas through such cells. It can be heated efficiently. Further, generally, a ceramic sintered body having a honeycomb structure is obtained by firing a molded body by extrusion molding, and it is difficult to form a molded body having a large cross-sectional area by extrusion molding. By connecting the honeycomb structure portions in a direction orthogonal to the axial direction, the cross-sectional area of the conductive heating element is increased. Thereby, it is possible to provide a volatile organic compound processing apparatus with a large amount of untreated gas.

  Further, the connecting portion connecting the plurality of honeycomb structure portions is firmly integrated with the honeycomb structure portion by sintering the ceramics. Ceramic sintered bodies generally have high mechanical strength at high temperatures. As a result, there is a low risk that cracks and the like will occur in the connecting part even when used at high temperatures, and the conductive heating element has excellent durability, so that efficient heating of the untreated gas in the heating part, Can be done continuously over a long period of time.

  As described above, as an effect of the present invention, it is possible to provide a volatile organic compound processing apparatus that can be downsized, has a low running cost, has high safety, and has higher processing efficiency and durability.

It is a block diagram which shows schematic structure of the volatile organic compound processing apparatus of this embodiment. It is a front view (figure seen from the heating part side) of the principal part of the volatile organic compound processing apparatus of FIG. It is a rear view (figure seen from the catalyst part side) of the principal part of the volatile organic compound processing apparatus of FIG. It is the XX sectional view taken on the line in FIG. It is the YY sectional view taken on the line in FIG. It is explanatory drawing explaining dispersion | distribution of gas. (A) perspective view of honeycomb structure part (b) cross-sectional view orthogonal to the axial direction. It is a figure explaining the manufacturing method of an electroconductive heat generating body provided with a honeycomb structure part and a connection part. It is (a) front view (figure seen from the heating part side) of the volatile organic compound processing apparatus of other embodiment, and (b) Y2-Y2 sectional view taken on the line.

  Hereinafter, a volatile organic compound processing apparatus (hereinafter simply referred to as “VOC processing apparatus”) according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7. The VOC processing apparatus 1 according to the present embodiment includes a conductive heating element 20 (hereinafter, simply referred to as “heating element 20”) in which a communicating hole through which a gas flows is formed, and a positive and negative pair for energizing the heating element 20. The heating unit 2 includes a heating unit 2 that heats the gas flowing through the communication hole by the heat generation of the heating unit 20 by energization, and the catalyst unit 31 that reduces the oxidative decomposition temperature of the volatile organic compound. 2 and a catalyst unit 3 that is provided on the downstream side of the gas flow and oxidatively decomposes volatile organic compounds contained in the gas heated by the heating unit 2, and the heating unit 2 includes electrodes 21a, A metal layer 23 integrated and laminated on the end face of the heating element 20 on the 21b side, and a steel wool layer 22 provided as a conductive elastic body layer between the metal layer 23 and the electrodes 21a and 21b, respectively. .

  As shown in FIG. 1, the VOC processing apparatus 1 includes a gas introduction path 8 that leads gas from the suction port 6 to the heating unit 2, a gas discharge path 9 that leads gas from the catalyst unit 3 to the discharge port 7, and a gas And a heat exchanger 4 for exchanging heat between the gas flowing through the introduction path 8 and the gas flowing through the gas discharge path 9. Furthermore, a fan 18 that sucks gas by driving a motor (not shown) is attached to the suction port 6. In addition, although detailed illustration is abbreviate | omitted, the heat exchanger 4 becomes a structure which wound the gas discharge path 9 around the gas introduction path 8. FIG.

  In the heating unit 2, as shown mainly in FIG. 4, two rows of heating elements 20 are provided in the gas flow direction (shown in the direction from the bottom to the top of the drawing), and heat is generated in the direction perpendicular to the gas flow direction. Three rows of bodies 20 are provided. Each heating element 20 includes three honeycomb structures 10 as mainly shown in FIG. Here, the honeycomb structure portion 10 is formed of a conductive silicon carbide ceramic sintered body, and is partitioned by a plurality of partition walls 12 extending in a single axial direction Z as shown in FIG. A plurality of cells 11 are provided.

  Further, in each heating element 20, the three honeycomb structure parts 10 are connected to each other in a direction perpendicular to the axial direction (up and down direction in FIG. 2) via the connection part 15. And the connection part 15 is formed with the electroconductive silicon carbide ceramic sintered compact, and is integrated with the honeycomb structure part 10 by sintering. In FIG. 2, the size of the cells 11 and the thickness of the partition walls 12 are exaggerated in order to clearly show the configuration, and the number of the cells 11 in the honeycomb structure portion 10 is also shown smaller than the actual number. .

  In order to manufacture the heating element 20 having such a configuration, for example, as shown in FIG. 8, a plurality of extruded bodies 10g formed into a honeycomb structure by extrusion molding of a ceramic material to be a conductive ceramic sintered body. Make it. Then, a sheet-shaped unfired body 15g formed in a sheet shape with a ceramic material to be a conductive ceramic sintered body is sandwiched between adjacent extruded molded bodies 10g and bonded together. The extrudate 10g and the sheet-shaped green body 15g are sintered by firing in a state where the extruded body 10g and the sheet-shaped green body 15g are bonded together, and the heating element in which both are integrated. 20 is obtained. Here, in one heating element 20, the length in the axial direction Z of the honeycomb structure portion 10 and the length of the connecting portion 15 in the same direction are the same.

  In the present embodiment, the extruded body 10g and the sheet-shaped green body 15g are formed by using the silicon carbide ceramic material having the same composition. As a result, the partition wall 12 and the connecting portion 15 of the honeycomb structure 10 are: The porous sintered body has substantially the same porosity, thermal conductivity, and electrical conductivity. Silicon carbide is close to an insulator in the case of high purity, but becomes a semiconductor by containing a small amount of impurities.

  The heating element 20 formed by connecting the honeycomb structure portion 10 with the connecting portion 15 as described above has one end connected to the electrode 21a via the metal layer 23 and the steel wool layer 22, and the other end connected to the electrode 21a. The metal layer 23 and the steel wool layer 22 are connected to the electrode 21b. Hereinafter, when it is not necessary to distinguish between the electrode 21a and the electrode 21b, they will be collectively referred to as the electrode 21. Here, the metal layer 23 is formed by thermal spraying of aluminum. The steel wool layer 22 is formed of stainless steel.

  Each heating element 20 is accommodated in a casing 29 of the heating unit 2, and through holes are formed in the top plate 29 t and the bottom plate 29 b of the casing 29. Bolts 25 for pressing the electrode 21 and fixing it to the heating element 20 are inserted into these through holes. Further, a substantially U-shaped support plate 26 is attached to the top plate 29t and the bottom plate 29b with the opening side facing the top plate 29t and the bottom plate 29b, respectively. A coiled spring member 27 having 25 shaft portions inserted therein is accommodated. In this state, the spring member 27 is in a compressed state between the flange portion provided along the outer periphery of the shaft portion of the bolt 25 and the support plate 26, and the electrode 21 is connected to the heating element 20 via the bolt 25. It is energizing in the direction toward. In order to prevent the electrodes 21 connected to the heating elements 20 in different rows from being short-circuited via the bolts 25 and the casing 29, a heat insulating insulating layer 24 is interposed between the bolts 25 and the electrodes 21. ing.

  As shown mainly in FIG. 4, a heat insulating insulating layer 24 is filled between the heating element 20 and the casing 29 and between the heating elements 20 adjacent in the direction orthogonal to the gas flow direction. . On the other hand, in the gas flow direction, a heat insulating insulating layer is not filled between the heating element 20 and the heating element 20, and a space 28 is formed.

  In the catalyst unit 3, as shown mainly in FIG. 5, the catalyst body 31 is accommodated in the casing 39, and the outer surface of the catalyst body 31 excluding the cross section through which the gas flows is covered with a heat insulating material 34. ing. The catalyst body 31 of the present embodiment is formed by supporting a noble metal catalyst on a porous cordierite ceramic honeycomb structure.

  Next, gas processing in the VOC processing apparatus 1 of the present embodiment will be described. First, an untreated gas containing VOC discharged from a factory or business place is sucked from the suction port 6 by the fan 18, and then flows through the gas introduction path 8 and is introduced into the heating unit 2. At this time, in the heating unit 2, the heating element 20 generates heat by energizing the electrodes 21a and 21b. Therefore, the untreated gas is heated when passing through the heating element 20. Here, since each heating element 20 includes the honeycomb structure portion 10 in which a large number of cells 11 are arranged, the gas is efficiently heated when flowing through the cells 11.

  In addition, since the partition walls 12 of the honeycomb structure 10 are porous, minute dust and particulate matter present in the gas are collected by pores opened in the partition walls 12.

  In the heating unit 2 of the present embodiment, the power generators 2 are provided in two rows in the gas flow direction, and a space 28 is formed between them, so that the gas that has passed through the heating elements 20 in the upstream row is downstream. Before it flows into the heating elements 20 in the side row, it hits the front surface and easily diffuses in the space 28 (see FIG. 6). Thereby, the gas introduced into the heating part 2 from the end part of the gas introduction path 8 is prevented from passing through only a part of the heating element 20. In the present embodiment, the power supply to the heating element 20 is adjusted so that the heating element 20 is maintained at about 300 ° C.

  The untreated gas heated by passing through the heating element 20 then flows into the catalyst unit 3 and passes through the catalyst body 31 which is a honeycomb structure on which the catalyst is supported. At this time, since the untreated gas has already been heated to about 300 ° C. in the heating unit 30 so that VOC can be oxidatively decomposed in the presence of the catalyst, VOCs are oxidatively decomposed at a lower temperature than when oxidatively decomposed by direct combustion.

  Then, the treated gas after the oxidative decomposition of the VOC flows through the gas discharge passage 9 and enters the heat exchanger 4, where it heats the untreated gas flowing through the gas introduction passage 8 to become a low temperature, and is discharged. It is discharged from the outlet 7 into the outside air.

  As described above, according to the VOC processing apparatus 1 of the present embodiment, the heating element 20 itself is a structure in which the gas is circulated instead of being heated from the outside by an external heat source such as a heater or a burner. Since self-heats, the gas can be efficiently heated by energization. Further, in order to heat the gas, it is sufficient to continuously pass the gas through the cell 11 of the heating element 20, so that the entire apparatus is compared with the conventional apparatus in which the gas is stored in the combustion chamber and heated externally. It is possible to reduce the size.

  In addition, since the heating element 20 and the catalyst body 31 are the main components, and the catalyst unit 3 is provided immediately after the heating unit 2, the entire apparatus can be reduced in size. It becomes.

  In the present embodiment, the catalyst is not supported on the porous silicon carbide ceramics that is the heating element 20, but the catalyst unit 3 is arranged downstream of the heating unit 2 as a separate structure from the heating unit 2. Is provided. Therefore, the temperature of the untreated gas can be increased in advance by the heating unit 2 up to 300 ° C. sufficient for the oxidative decomposition of VOC in the presence of the catalyst, and then introduced into the catalyst unit 3. As a result, it is possible to fully oxidize and decompose VOC at a low temperature by fully exerting the action of the catalyst.

  In addition, fine dust and particulate matter contained in the untreated gas are collected by the filtering action in the honeycomb structure 10. In the present embodiment, since the catalyst body 31 and the heating element 20 are configured separately, unlike the case where the catalyst is supported on the heating element, the collected material does not cover the catalyst. . Thereby, the catalyst body 31 can be used over a long period of time.

  Further, a metal layer 23 and a steel wool layer 22 are interposed between the electrode 21 and the heating element 20, and the metal layer 23 is integrally laminated on the entire end surface of the heating element 20 on the electrode 21 side by thermal spraying of aluminum. ing. Thereby, the electrode 21 and the metal layer 23 can be electrically connected to each other at many contact points by steel wool, and the entire heating element can be energized through the metal layer 23.

  Furthermore, since the degree of adhesion between the electrode 21 and the heating element 20 through the steel wool layer 22 and the metal layer 23 can be increased by urging the spring member 27, the heating element 20 can be easily energized. Further, the steel wool is compressed by the urging of the spring member 27, the contact point between the steel wool layer 22 and the metal layer 23 is increased, and the conduction between the two layers becomes better. In addition, since the thermal expansion of the heating element 20 can be absorbed by the elastic deformation of the spring member 27, the occurrence of distortion, cracks, and the like due to the thermal stress in the heating unit 2 is effectively prevented.

  In addition, since the steel wool layer 22 is formed of stainless steel wool, further oxidation is suppressed by the surface immobile film, and the durability of the heating unit 2 through which the heated gas flows is high. It has become a thing.

  Further, both the honeycomb structure portion 10 and the connecting portion 15 are formed of a silicon carbide based ceramic sintered body. The silicon carbide based ceramic sintered body has high strength and high thermal conductivity and low thermal expansion coefficient. Therefore, it has excellent thermal shock resistance. Therefore, it is suitable as the heating element 20 that is repeatedly heated and cooled with use, and the durability of the entire heating element 20 is high. In addition, since the heat conductivity is high, the temperature of the heating element 20 rises rapidly due to energization, so that the untreated gas can be efficiently heated. Furthermore, since the silicon carbide based ceramic sintered body is excellent in oxidation resistance and corrosion resistance, it is suitable as a heating element 20 for heating an untreated gas containing various VOCs.

  In addition, since the connecting portion 15 that connects the plurality of honeycomb structure portions 10 is integrated with the honeycomb structure portion 10 by sintering, the strength of the entire heating element 20 is high, and cracks and the like occur in the connecting portions 15. Is also suppressed. Moreover, in this embodiment, since the honeycomb structure part 10 and the connection part 15 are the silicon carbide ceramic sintered bodies of the same composition, the thermal expansion coefficient is equal, and generation | occurrence | production of the thermal stress accompanying a heating is suppressed. Further, since the connecting portion 15 is also a conductive ceramic sintered body, there is no need to provide electrodes on each of the plurality of honeycomb structure portions 10, and the heating element 20 formed by connecting the plurality of honeycomb structure portions 10 is also possible. It is sufficient to provide the electrodes 21 at both ends. Thereby, the VOC processing apparatus 1 can be made into a simple structure.

  In addition, it is difficult to form a honeycomb structure having a large cross-sectional area by extrusion molding. However, in the present embodiment, a plurality of honeycomb structure portions 10 are connected in a direction orthogonal to the axial direction to cross-sectional area of the heating element 20. By increasing the amount of gas, a large amount of untreated gas can be treated.

  Further, in the present embodiment, the electrodes 21a and 21b are connected to both ends of the heating element 20 formed by connecting the plurality of honeycomb structure parts 10 in the direction orthogonal to the axial direction, respectively. Are electrically connected in series. Therefore, by adjusting the number of the honeycomb structure parts 10, the distance between the electrodes 21a and 21b can be adjusted and the magnitude of the electrical resistance can be adjusted. As a result, the silicon carbide ceramics has NTC characteristics in which the electrical resistance decreases as the temperature rises. By adjusting the electrical resistance value between the electrodes 21a and 21b, the current value is prevented from becoming excessive. However, it is possible to obtain a large amount of heat generation using a commercial power source. That is, it is possible to provide a volatile organic compound processing apparatus that does not require special equipment and is easy to introduce even for small and medium-sized businesses.

  Moreover, since the VOC processing apparatus 1 of this embodiment is provided with the heat exchanger 4, it can utilize the exhaust heat of processed gas effectively, can introduce | transduce into a heating part 30 after heating an unprocessed gas beforehand. . Thereby, the energization amount to the heat generating body 20 can be reduced, and running cost can be suppressed. In addition, the treated gas can be prevented from being discharged into the atmosphere in a high temperature state and adversely affecting the environment.

  In addition to the above-described configuration, the VOC processing apparatus 1 according to the present embodiment includes a gas flow path dispersion member that disperses the gas flow path in the heating unit 2 on the upstream side of the gas flow from the heating element 20. Can do. For example, as shown in FIG. 6, a dispersion plate 41 having a large number of small through holes can be provided in the vicinity of the end of the gas introduction path 8. Further, a dispersion blade 42 in which a plurality of blades are provided on the outer surface of the base having a conical section can be provided in the vicinity of the front surface of the heating element 20 on the downstream side. Here, the dispersion plate 41 and the dispersion blades 42 both correspond to “gas flow path dispersion members”.

  With the above-described configuration, the gas flowing out from the end of the gas introduction path 8 first disperses in various directions by passing through a large number of through holes of the dispersion plate 41. The dispersed gas is then guided and distributed by the dispersion blades 42, and the diameter of the gas flow passage is expanded. Accordingly, even when the total cross-sectional area of the plurality of heating elements 20 arranged in a row is larger than the cross-sectional area of the gas introduction path 8, the gas is allowed to pass through the entire heating element 20 and the entire heating element 20. The heat can be effectively utilized to heat the gas.

  The present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the above-described embodiments, and various improvements can be made without departing from the scope of the present invention as described below. And design changes are possible.

  For example, in the above embodiment, the case where the pair of electrodes 21a and 21b is connected to each of the two rows of the heating elements 2 in the gas flow direction is illustrated, but the present invention is not limited to this. The connection method can be changed as appropriate depending on the type (electric resistance value), size, etc. of the heating element. For example, as shown in FIG. 9, one end of each of the two rows of heating elements 20 in the gas flow direction is connected by a conductive conducting portion 28, so that the two rows of heating elements 2 in the gas flow direction are electrically connected. It can be set as the structure connected in series. By adopting such a configuration, it is possible to increase the distance through which the current flows through the heating element 20 between the pair of electrodes 21a and 21b without changing the number of the honeycomb structure portions 10 in one heating element 20.

  Moreover, although the case where the some honeycomb structure part 10 was connected by the connection part 15 which is a ceramic sintered compact was illustrated, the structure which the some honeycomb structure part 10 connects is not limited to this. For example, a metal layer can be provided by metal spraying on the end faces connected in the honeycomb structure 10, and a steel wool layer can be provided between each metal layer of the adjacent honeycomb structure 10. That is, it is a form in which the connecting portion is constituted by two metal layers respectively provided in adjacent honeycomb structure portions 10 and a steel wool layer therebetween. By setting it as such a structure, it can energize favorably between the adjacent honeycomb structure parts 10 via a metal layer and a steel wool layer. And if stainless steel wool is used and a steel wool layer is formed, durability can be improved.

  Furthermore, although the case where one catalyst body is provided in the catalyst portion is illustrated, the present invention is not limited to this, and a configuration in which a plurality of catalyst bodies are arranged in the gas flow direction can be employed. In that case, the type of catalyst may be the same or different.

  In addition, the catalyst body is exemplified by a catalyst in which a catalyst is supported on a porous body. However, the present invention is not limited to this. For example, the catalyst itself such as a foam metal can be used as the porous structure.

1 VOC treatment equipment (volatile organic compound treatment equipment)
2 Heating unit 3 Catalyst unit 10 Honeycomb structure unit 11 Cell 12 Partition 15 Connection unit 20 Heating element (conductive heating element)
21, 21a, 21b Electrode 22 Steel wool layer 23 Metal layer 27 Spring member 31 Catalyst body

JP-A-11-212430 JP 2005-279570 A

Claims (3)

A conductive heating element in which a communicating hole for circulating a gas is formed, and an electrode for energizing the conductive heating element, and a gas that circulates through the communicating hole by heat generation of the conductive heating element by energization A heating section for heating
A catalyst unit that includes a catalyst body that lowers the oxidative decomposition temperature of the volatile organic compound, and that is provided on the downstream side of the gas flow from the heating unit and oxidatively decomposes the volatile organic compound contained in the gas heated by the heating unit; Comprising
The heating unit includes a metal layer integrated and laminated on an end face of the conductive heating element on the electrode side by solidification of molten metal, and a conductive elastic layer provided between the metal layer and the electrode A volatile organic compound processing apparatus comprising: The volatile organic compound processing apparatus according to claim 1, wherein the conductive elastic layer is made of stainless steel wool. The conductive heating element is formed of a conductive ceramic sintered body and has a plurality of honeycomb structures each having a honeycomb structure including a plurality of cells partitioned by a plurality of partition walls extending in a single axial direction. And a connecting portion that is formed of a conductive ceramic sintered body integrated with the honeycomb structure portion and connects the adjacent honeycomb structure portions in a direction perpendicular to the axial direction. The volatile organic compound processing apparatus according to claim 1 or 2.

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