JP2012207536A - Exhaust gas treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas treatment apparatus capable of efficiently removing particulate matter in exhaust gas emitted from an internal combustion engine and efficiently reforming nitrogen oxides etc.SOLUTION: The exhaust gas treatment apparatus 10, connected to discharge pipes 3, 4 of an internal combustion engine 1, for treating exhaust gas containing particulate matter includes: a housing 11 having a hollow pipe structure; an inlet port 12 for taking exhaust gas into the housing; a metal mesh body 14 allowing passage of the exhaust gas taken into the housing from the inlet port 12; a metal structure 17 to hinder passage of the particulate matter in the exhaust gas having passed through the metal mesh body 14; an ultraviolet light generating member 18 for irradiating ultraviolet light toward the metal mesh body 14 and the metal structure 17 to generate ozone or hydroxy radical; and an outlet port 13 for discharging the ultraviolet-irradiated exhaust gas from the housing 11.

Description

  The present invention relates to an exhaust gas treatment device. More specifically, the present invention relates to an exhaust gas processing apparatus capable of removing particulate matter in exhaust gas discharged from an internal combustion engine and reforming nitrogen oxides.

  The exhaust gas discharged from the internal combustion engine contains particulate matter (PM). Various studies for removing particulate matter have been proposed.

  Patent Document 1 discloses that plasma discharge is used to charge particulate matter with electrons generated at the time of discharge to promote adhesion to the manganese oxide-supporting substrate, and the particulate matter is oxidized by the catalytic action of manganese oxide. A technique of decomposing has been proposed. According to this technology, it is possible to directly oxidize and remove particulate matter even with OH radicals or ozone generated during plasma discharge, and further promote the removal of particulate matter.

  In Patent Document 2, particulate matter in exhaust gas is captured by a ceramic honeycomb filter, and heated when the captured particulate matter exceeds a preset allowable value, and the particulate matter is burned and removed. Techniques to do this have been proposed. In this technique, particulate matter is captured by a heat-resistant filter, and the captured particulate matter can be removed at an arbitrary timing.

  On the other hand, this inventor has proposed the processing apparatus using an ultraviolet-ray (patent document 3). This treatment apparatus includes a water holding body that is supplied with water and kept wet with water droplets, a mercury lamp that is installed at a close distance within 10 mm from the water holding body, and that irradiates the water holding body with ultraviolet light having a wavelength of 254 nm. It is an apparatus which produces | generates OH radical from a water holding body with the energy of the irradiated ultraviolet-ray, controlling to the temperature range of 10 to 40 degreeC. In this processing apparatus, a gas containing ethylene is passed through a water retaining body having generated OH radicals, and ethylene generated from fresh food is decomposed and reformed into ethane and water.

JP 2009-508840 A JP 2005-337153 A JP 2005-261428 A

  Since the technique proposed in Patent Document 1 uses plasma discharge and requires a large amount of power, it is not suitable for an internal combustion engine provided in a mobile machine such as an automobile from the viewpoint of power supply. Further, in an internal combustion engine such as an automobile engine, the exhaust gas has a high flow rate and the moving speed of the particulate matter contained in the exhaust gas is also high. When the plasma discharge method is applied to the combustion of particulate matter that moves at high speed, the contact time between the particulate matter and the discharge path is short, so that the transfer efficiency of discharge energy is low. Therefore, in order to burn the particulate matter effectively, there is a drawback that the discharge energy must be increased.

  From this point of view, the combustion technology of particulate matter using plasma discharge is not suitable for an internal combustion engine provided in a mobile machine such as an automobile because the apparatus is complicated and expensive and is increased in size.

  The technique proposed in Patent Document 2 uses a honeycomb filter, so that clogging is likely to occur and exhaust gas flow resistance increases.

  The technique of Patent Document 3 proposed by the present inventor is aimed at reforming ethylene or the like produced from fresh food, and therefore the technique is applied to a processing apparatus for an internal combustion engine to remove particulate matter. This is difficult to apply as it is in terms of the usage environment of the apparatus.

  The present invention has been made to solve the above-mentioned problems, and its object is to efficiently remove particulate matter in exhaust gas discharged from an internal combustion engine and reform nitrogen oxides and the like. It is an object of the present invention to provide an exhaust gas treatment device that can perform the above-described process.

  An exhaust gas processing apparatus according to the present invention for solving the above-mentioned problems is an exhaust gas processing apparatus for processing exhaust gas containing particulate matter by being connected to an exhaust pipe of an internal combustion engine, wherein the housing has a hollow tube structure An introduction port for taking in exhaust gas into the housing, a metal mesh body through which the exhaust gas taken into the housing from the introduction port, and passage of particulate matter in the exhaust gas that has passed through the metal mesh body A metal structure that hinders the irradiation, an ultraviolet ray generating member that irradiates ultraviolet rays toward the metal mesh body and the metal structure to generate ozone or hydroxy radicals, and exhausts exhaust gas after being irradiated with ultraviolet rays from the housing And a discharge port.

  According to the present invention, the housing through which the exhaust gas containing the particulate matter passes is provided with the metal mesh body that allows the exhaust gas to pass through, and the metal structure that prevents the passage of the particulate matter in the exhaust gas. Since it has an ultraviolet ray generating member that generates ozone or hydroxy radicals by irradiating the metal mesh body and metal structure with ultraviolet rays, the generated ozone or hydroxy radicals can oxidize and remove particulate matter in the exhaust gas. The nitrogen oxides in the exhaust gas can be oxidized and reformed into harmless gas. Since such an exhaust gas processing apparatus includes an ultraviolet ray generating member that does not require large electric power such as plasma discharge, the apparatus can be reduced in weight and size and can be realized with respect to an internal combustion engine included in a mobile machine such as an automobile. It can be preferably applied.

  In the exhaust gas treatment apparatus according to the present invention, the metal structure is a metal fiber laminate that passes gas but captures particulate matter, and the ultraviolet ray generating member is a member that generates ultraviolet rays having a wavelength of 200 nm or less. A power source for applying a voltage having the metal mesh body as a positive electrode and the metal structure as a negative electrode, and the particulate matter in the exhaust gas that has passed through the metal mesh body is negative by the application of the voltage. Space charge is attached, and the particulate matter decelerates as it approaches the metal fiber laminate.

  According to the present invention, the apparatus further includes a power source that applies a voltage having the metal mesh body as a positive electrode and the metal structure as a negative electrode, and the particulate matter in the exhaust gas that has passed through the metal mesh body is negative by the application of the voltage. A space charge is attached, and the particulate matter decelerates as it approaches the metal fiber laminate. Since the decelerated particulate matter can come into contact with ozone or hydroxy radical generated by irradiation with ultraviolet rays having a wavelength of 200 nm or less for a long time, the particulate matter can be efficiently oxidized and removed. Moreover, since the metal fiber laminate that passes the gas but captures the particulate matter is used as the metal structure, the particulate matter captured by the metal fiber laminate can also come into contact with the generated ozone or hydroxy radical for a long time. Therefore, the particulate matter can be efficiently oxidized and removed.

  In the exhaust gas processing apparatus according to the present invention, a processing unit configured in the order of the metal mesh body, the ultraviolet ray generating member, and the metal structure from the introduction port side toward the discharge port side includes a shaft of the housing. A plurality are arranged in the direction.

  According to the present invention, a plurality of processing units configured in the order of the metal mesh body, the ultraviolet ray generating member, and the metal structure from the introduction port side to the discharge port side are arranged in the axial direction of the housing. By arranging two or more processing units in the axial direction, for example, even when fine particulate matter cannot be sufficiently oxidized and removed by the first processing unit, it can be oxidized and removed by the second and subsequent processing units. Further, even when nitrogen oxide or the like cannot be oxidized and reformed by the first processing unit, it can be oxidized and reformed by the second and subsequent processing units.

  In the exhaust gas treatment apparatus according to the present invention, the metal mesh body is a plurality of titanium oxide-coated mesh cylinders extending in the axial direction of the housing, and the metal structure is the titanium oxide-coated mesh cylinder. A shielding metal plate that is disposed at a position that obstructs the hollow portion in the middle, and blocks passage of exhaust gas in the titanium oxide-coated mesh cylinder to change the course to another titanium oxide-coated mesh cylinder; The generating member is a member that is provided at the axial center position of the housing and extends in the axial direction to generate ultraviolet rays having a wavelength of 300 nm to 400 nm.

  According to this invention, the metal mesh body is a plurality of titanium oxide-coated mesh cylinders, the metal structure is a shielding metal plate that intercepts the hollow portion of the titanium oxide-coated mesh cylinder, and the shielding metal plate is Since the passage of exhaust gas in the cylinder made of titanium oxide-coated mesh is blocked and the course is changed to another cylinder made of titanium oxide-coated mesh, the exhaust gas is not changed in the course, so multiple titanium oxide-coated meshes Proceed through the cylinder. The titanium oxide-coated mesh generates ozone or hydroxy radicals by photochemical reaction with 300 nm to 400 nm ultraviolet rays generated from the ultraviolet ray generating member, so that the particles in the exhaust gas that advance without changing the course of the ozone or hydroxy radicals. Oxidation and removal of nitrogenous substances and oxidation reforming of nitrogen oxides and the like.

  In the exhaust gas treatment apparatus according to the present invention, the titanium oxide-coated mesh cylinders have the same diameter and are provided adjacent to each other at a predetermined interval in the housing, or the titanium oxide-coated mesh cylinders Have different diameters and are provided concentrically within the housing.

  According to the present invention, (a) the titanium oxide-coated mesh cylindrical body has the same diameter and is provided adjacent to the housing at a predetermined interval, or (a) the titanium oxide-coated mesh cylindrical body has a different diameter, and the housing Since it is configured so as to be concentrically provided inside, it can be advanced through a plurality of titanium oxide-coated mesh cylinders without changing the course of the exhaust gas in any configuration. As a result, the distance traveled by the exhaust gas can be lengthened and contacted with the generated ozone or hydroxy radical for a long time, so that oxidation removal of particulate matter in the exhaust gas and oxidation reforming of nitrogen oxides and the like can be further performed. Can be done efficiently.

  According to the exhaust gas treatment apparatus of the present invention, generated ozone or hydroxy radicals can oxidize and remove particulate matter in the exhaust gas, and oxidize nitrogen oxides in the exhaust gas to improve the harmless gas. You can quality. Such an exhaust gas treatment device includes an ultraviolet ray generating member that does not require large electric power, such as plasma discharge. Therefore, the device can be reduced in weight and size, and the internal combustion engine provided in a mobile machine such as an automobile can be realized. The present invention can be preferably applied.

  Moreover, according to the exhaust gas treatment apparatus of the present invention, the particulate matter can be decelerated as it approaches the metal fiber laminate, and therefore, it can be in contact with ozone or hydroxy radicals that have produced the particulate matter for a long time. As a result, the particulate matter can be efficiently oxidized and removed.

  Further, according to the exhaust gas treatment apparatus of the present invention, the exhaust gas can be advanced through a plurality of titanium oxide-coated mesh cylinders without changing the course of the exhaust gas. Since ozone or hydroxy radicals are generated by photochemical reaction with 300 to 400 nm ultraviolet rays generated from the ozone, the ozone or hydroxy radicals oxidize and remove particulate matter in the exhaust gas that does not change the course, or nitrogen oxides Etc. can be oxidized and modified.

  As described above, according to the exhaust gas treatment apparatus of the present invention, (i) since a low-power ultraviolet ray generating member is used, unlike plasma discharge, the apparatus can be reduced in power, simplified and reduced in weight, The present invention can be preferably applied to an internal combustion engine provided in a mobile machine such as an automobile. (ii) Since the particulate matter can be slowed down or the path of the exhaust gas can be lengthened, it can be brought into contact with ozone or a hydroxyl radical for a long time, and oxidation removal and oxidation reforming can be performed efficiently. it can. (iii) Since the titanium oxide in the presence of ultraviolet rays or air is irradiated with ultraviolet rays, the generated ozone or hydroxy radicals are used to efficiently remove particulate matter and oxidize and reform nitrogen oxides, etc. Can do.

1 is a layout view when an exhaust gas treatment device according to the present invention is connected to an exhaust port of an internal combustion engine. It is sectional drawing which shows an example of the exhaust-gas processing apparatus which concerns on this invention. It is a top view which shows an example of a metal mesh body. It is a front view which shows an example of the mercury lamp which is an ultraviolet-ray generation member. It is sectional drawing which shows another example of the exhaust-gas processing apparatus which concerns on this invention. It is sectional drawing which shows another example of the exhaust-gas processing apparatus which concerns on this invention. It is a top view which shows an example of the cylinder made from a titanium oxide covering mesh which comprises the exhaust-gas processing apparatus of FIG. It is a top view which shows an example of the holding plate used for the exhaust gas processing apparatus of FIG. It is a left view which shows another example of the exhaust-gas processing apparatus which concerns on this invention.

  Hereinafter, an exhaust gas treatment apparatus according to the present invention will be described with reference to the drawings. The technical scope of the present invention is not limited only to the following description and drawings.

[Basic configuration]
As shown in FIG. 1, an exhaust gas treatment apparatus 10 according to the present invention is connected to particles in the middle of exhaust pipes (for example, mufflers made of SUS) 3 and 4 connected to an exhaust port 2 of an internal combustion engine (engine) 1. Is an apparatus for treating exhaust gas containing particulate matter. Usually, it has the inlet 12 and the outlet 13 as shown in FIG. 2 etc., the inlet 12 is connected to the muffler 3, and the outlet 13 is connected to the muffler 4.

  As shown in FIGS. 2 to 9, the basic configuration includes a housing 11 having a hollow tube structure, an introduction port 12 for taking exhaust gas into the housing, and exhaust gas taken into the housing from the introduction port 12. The metal mesh body 14 that passes through the metal mesh body 14, the metal structure 17 that prevents the passage of particulate matter in the exhaust gas that has passed through the metal mesh body 14, and the metal mesh body 14 and the metal structure body 17 are irradiated with ultraviolet rays. An ultraviolet ray generating member 18 that generates ozone or hydroxy radicals and an exhaust port 13 that exhausts exhaust gas after being irradiated with ultraviolet rays from the housing 11 are provided.

  In the present invention, a metal mesh body 14 that allows exhaust gas to pass therethrough and a metal structure 17 that prevents passage of particulate matter in the exhaust gas are provided in a housing 11 through which exhaust gas containing particulate matter passes. Furthermore, an ultraviolet ray generating member 18 is provided that generates ozone or hydroxy radicals by irradiating the metal mesh body 14 and the metal structure 17 with ultraviolet rays. As a result, the generated ozone or hydroxy radical can oxidize and remove particulate matter in the exhaust gas, and can also oxidize nitrogen oxides in the exhaust gas and reform it into a harmless gas. Such an exhaust gas processing apparatus 10 includes an ultraviolet ray generating member 18 that does not require large electric power, such as plasma discharge, so that the apparatus can be reduced in weight and size and can be used as an internal combustion engine included in a mobile machine such as an automobile. On the other hand, there is a special effect that it can be preferably applied.

  The exhaust gas treatment apparatus 10 according to the present invention can be broadly divided into the following two embodiments as embodiments in which ultraviolet rays are irradiated toward the metal mesh body 14 and the metal structure 17 to generate ozone or hydroxy radicals.

[First Embodiment]
The exhaust gas treatment apparatus 10 according to the first embodiment has the above-described basic configuration, and further, as shown in FIG. 2, (1) the metal structure 17 passes through the gas but captures the particulate matter. A metal fiber laminate (represented by reference numeral 17), (2) the ultraviolet ray generating member 18 is a member that generates ultraviolet rays having a wavelength of 200 nm or less, and (3) the metal mesh member 14 is a positive electrode, and the metal structure 17 Is further provided with a power supply 21 for applying a voltage having a negative polarity.

  According to the exhaust gas treatment apparatus 10 according to the first embodiment having such a configuration, the particulate matter is ozone in order to increase the efficiency with which the particulate matter in the exhaust gas reacts with ozone or hydroxyl radicals to be oxidized and removed. Alternatively, the time for contact with hydroxy radicals can be increased. That is, when the voltage from the power source 21 is applied, the particulate matter in the exhaust gas that has passed through the metal fiber laminate 14 attaches a negative space charge. Therefore, the particulate matter attached with the negative space charge is a metal fiber. The closer to the laminate 17, the slower the speed. As a result, the time for which the particulate matter captured by the metal fiber laminate 17 is brought into contact with ozone or hydroxy radicals can be lengthened.

  Hereinafter, each configuration will be described in detail.

(housing)
The housing 11 has a hollow structure in which both ends in the longitudinal direction are open, and forms an outer shell of the apparatus. As long as it has a hollow structure, it may be a cylindrical structure having a circular cross section as shown in FIG. 2 or a rectangular tube structure having a polygonal cross section. One end of the housing 11 in the longitudinal direction is an introduction port 12 for taking in exhaust gas into the housing, and the other end is an exhaust port 13 for discharging exhaust gas after processing.

  The material of the housing 11 is not particularly limited as long as the material is durable to vacuum ultraviolet rays having a wavelength of 200 nm or less, but a steel pipe such as stainless steel or carbon steel is preferably used. Since the housing 11 includes the ultraviolet ray generating member 18 therein, the housing 11 preferably has a structure that blocks leakage of vacuum ultraviolet rays emitted from the ultraviolet ray generating member 18 to the outside. In the case of the cylindrical housing 11, the inner diameter is, for example, about 30 mm to 100 mm, preferably about 50 mm to 80 mm.

(Inlet and outlet)
As shown in FIG. 2, the inlet 12 and the outlet 13 are openings at both ends in the longitudinal direction of the housing 11. The inlet 12 is an opening that takes in the exhaust gas into the housing 11, and the outlet 13 is an opening that discharges the exhaust gas that has passed through the metal structure 17 described later. As shown in FIG. 2, the introduction port 12 and the discharge port 13 may be configured to have the same inner diameter as the inner diameter of the housing 11, or may be configured to be drawn so as to have a small inner diameter. It may be configured in a form that has been expanded to have a large inner diameter. Mufflers 3 and 4 are connected to the inlet 12 and the outlet 13.

(Metal mesh body)
The metal mesh body 14 is a mesh structure that can pass exhaust gas taken into the housing from the inlet 12. As shown in FIG. 2, the metal mesh body 14 is provided between the inlet 12 and the ultraviolet ray generating member 18 so as to block the axial direction in the housing 11. The shape of the metal mesh body 14 is the same as or substantially the same as the shape of the inner surface of the housing 11. For example, when the inner surface of the housing 11 is circular, it is formed in a circular shape as shown in FIG. A frame 15 as shown in FIG. 3 is provided on the outer edge of the metal mesh body 14 in order to fit the metal mesh body 14 to the inner surface of the housing 11.

  In the example of FIG. 3, the metal mesh body 14 is formed by a net (mesh) 16 that intersects inside and outside the frame 15 in the vertical and horizontal directions. The fineness of the mesh is not particularly limited, and may be a mesh having an opening through which, for example, 2 μm particulate matter can pass freely without resistance. Note that the net 16 is not necessarily required as long as it can pass the exhaust gas.

  The material of the metal mesh body 14 is preferably a metal that is durable against vacuum ultraviolet rays having a wavelength of 200 nm or less and that is also durable against exhaust gas components such as nitrogen oxides and sulfur oxides. . As such a metal, for example, a tungsten mesh or a stainless steel mesh having a wire diameter of 0.4 mm and about 20 mesh is preferably adopted, but not limited thereto. The mesh represents the number of eyes per inch. For example, 20 mesh is 20 meshes per inch (eight meshes for 1 cm).

  The metal mesh body 14 becomes a positive electrode by a voltage applied between the metal mesh body 17 and a metal structure 17 described later. Since the negative space charge (negative charge) collects in the metal mesh body 14 which has become a positive electrode, all or part of the particulate matter contained in the exhaust gas passing through the metal mesh body 14 has a negative charge. It adheres and becomes negatively charged particulate matter and flows downstream.

(Metal structure)
The metal structure 17 is a metal fiber laminate 17 in which the gas in the exhaust gas that has passed through the metal mesh body 14 passes, but the particulate matter is captured. As shown in FIG. 2, the metal fiber laminate 17 is provided between the ultraviolet ray generating member 18 and the exhaust port 13 so as to block the axial direction in the housing 11. The shape of the metal fiber laminate 17 is the same as or substantially the same as the shape of the inner surface of the housing 11 like the metal mesh body 14 described above. For example, when the inner surface of the housing 11 is circular, it is formed in a circular shape. Yes. The outer edge of the metal fiber laminate 17 is also preferably provided with a frame for fitting the metal fiber laminate 17 to the inner surface of the housing 11 in the same manner as the metal mesh body 14 described above.

  The metal fiber laminate 17 is preferably a metal fiber laminate that allows gas in the exhaust gas to pass therethrough but does not allow particulate matter to pass through. Examples of the metal fiber laminate 17 include a nonwoven fabric made of metal fibers. Although the wire diameter of a metal fiber is not specifically limited, For example, it is preferable that a metal fiber with a diameter of about 20 μm is used. The opening of the metal fiber laminated body 17 should just be a magnitude | size which can prevent the passage of particulate matter of about 0.18 μm and can be captured, for example. As for the porosity of the metal fiber laminated body 17, it is preferable that the ratio for which a space | gap accounts is large so that gas can pass through, for example about 50%-85%. Note that the nonwoven fabric (metal fiber laminate 17) is not necessarily required as long as particulate matter in the exhaust gas can be captured.

  The material of the metal fiber laminate 17 is a metal that is durable against vacuum ultraviolet rays having a wavelength of 200 nm or less, and is also durable against exhaust gas components such as nitrogen oxides and sulfur oxides. preferable. As such a metal, for example, tungsten fiber and stainless steel fiber are preferably employed, but not limited thereto. Although the thickness of the metal fiber laminated body 17 is not specifically limited, For example, the thickness of about 1 mm-5 mm can be mentioned.

  This metal fiber laminated body 17 becomes a negative electrode by the voltage applied between the above-described metal mesh bodies 14. The metal structure 17 that has become a negative electrode adheres negative charges with the metal mesh body 14 provided on the upstream side, and acts to repel the negatively charged particulate matter electrostatically. As a result, the particulate matter to which negative space charges are attached is decelerated as it approaches the metal fiber laminate 17. The decelerated particulate matter has a longer contact time with ozone or hydroxy radicals generated by ultraviolet irradiation and is also captured by the metal fiber laminate 17, so that more efficient oxidative removal is possible.

(Power supply)
The power source 21 is a device that applies a voltage to the metal mesh body 14 that negatively charges the particulate matter in the exhaust gas and the metal fiber laminate 17 that electrostatically repels the particulate matter. A battery 23 is connected to the power source 21 as shown in FIG. The power source 21 is a DC power source or a DC pulse power source that applies a voltage using the metal mesh body 14 as a positive electrode and the metal fiber laminate 17 as a negative electrode. In particular, it is preferable to apply a DC pulse voltage.

(Ultraviolet generating member)
The ultraviolet ray generating member 18 is a member that generates ozone or hydroxy radicals by irradiating the metal mesh body 14 and the metal fiber laminate 17 with vacuum ultraviolet rays having a wavelength of 200 nm or less. As shown in FIG. 2, the ultraviolet ray generating member 18 is provided between the metal mesh body 14 and the metal fiber laminate 17, and specifically, toward the metal fiber laminate 17 that captures particulate matter. It is preferable that they are arranged so as to irradiate ultraviolet rays.

The ultraviolet ray generation member 18 is not particularly limited as long as it emits at least vacuum ultraviolet rays having a wavelength of 200 nm or less, and may emit only vacuum ultraviolet rays, or may emit vacuum ultraviolet rays and ultraviolet rays of 200 nm or more simultaneously. Good. For example, an arc discharge type ArAg lamp (wavelength 185 nm and wavelength 254 nm, manufactured by Okaya Electric Industrial Co., Ltd.), a dielectric barrier discharge type Xe ₂ excimer lamp (wavelength 172 nm, manufactured by Ushio Electric Co., Ltd.), a dielectric barrier discharge type An ArF excimer lamp (wavelength 193 nm, manufactured by Ushio Inc.), an ArF excimer laser (193 nm), an F ₂ laser (157 nm), and the like can be mentioned. A predetermined voltage is applied to the ultraviolet ray generating member 18 from a constant voltage device 22 provided outside, but since the power consumption is small, unlike the conventional plasma discharge, the device is reduced in power, simplified, and lightweight. And can be preferably applied to an internal combustion engine provided in a mobile machine such as an automobile.

  It is preferable that a plurality of the ultraviolet ray generating members 18 are arranged side by side on the metal mesh body side of the metal fiber laminate 17 so that the entire surface of the metal fiber laminate 17 having a disk structure can be irradiated uniformly. Although the arrangement mode is not particularly limited, it is preferable that the metal fiber laminates 17 having a disk structure are arranged at predetermined intervals, and specifically, the ultraviolet ray generating member 18 is attached to a holding frame. it can. By doing so, ozone generated by irradiation with vacuum ultraviolet rays or a single-lifetime hydroxy radical can be brought into contact with the particulate matter deposited on the metal fiber laminate 17, and as a result, the oxidative removal of the particulate matter is efficiently performed. Can be done automatically.

  FIG. 4 shows an example of an arc discharge U-tube lamp. This U-shaped tube lamp is composed of a light emitting unit 19 made of a glass tube and a base 20 that holds the light emitting unit 19. For example, when this U-shaped tube lamp is used, it is preferable to arrange a plurality of U-shaped tube lamps on the surface of the metal fiber laminate 17.

  Here, vacuum ultraviolet rays will be described. In general, ultraviolet rays are electromagnetic waves having a wavelength shorter than that of visible light and longer than that of X-rays, and are invisible light having a wavelength of 10 nm to 400 nm. Furthermore, those having a wavelength of 300 nm to 400 nm are referred to as near ultraviolet rays, those having a wavelength of 200 nm to 300 nm are referred to as far ultraviolet rays, and wavelengths of 10 nm to 200 nm are referred to as vacuum ultraviolet rays.

(Oxidation removal action and oxidation reforming action)
In the exhaust gas treatment apparatus 10 according to the present invention, the oxidation removal action on the particulate matter and the oxidation reforming action on the exhaust gas will be described in detail.

  The exhaust gas taken in from the introduction port 3 passes through the metal mesh body 14 which is a positive electrode when a voltage is applied. Since the metal mesh body 14 attracts negative space charges, the particulate matter to which the negative space charges are attached goes downstream in a negatively charged manner. The particulate matter directed toward the downstream is electrostatically repelled against the metal fiber laminate 17 that is applied with a voltage and serves as a negative electrode. As a result, the particulate matter is decelerated as it approaches the metal fiber laminate 17, and the particulate matter reaches the metal fiber laminate 17 in a decelerated state, so that it is mainly captured by the surface portion.

  On the other hand, vacuum ultraviolet rays emitted from the ultraviolet ray generating member 18 act on moisture in the exhaust gas to generate oxygen radicals and hydroxy radicals. Oxygen radicals combine with oxygen to become ozone. Vacuum ultraviolet rays act on oxygen in exhaust gas to generate ozone. Such ozone or hydroxy radicals are mainly present in the vicinity of the ultraviolet ray generating member 18 because they have a very short lifetime from generation to extinction. For this reason, it is preferable that the speed of the particulate matter passing through the vicinity of the ultraviolet ray generating member 18 is low, and the ultraviolet ray producing member 18 is disposed at a position close to the surface of the metal fiber laminate 17 on which the particulate matter is deposited. It is preferable. As a result, the particulate matter can be passed through the vicinity of the ultraviolet ray generating member 18 in a decelerated state, and further the particulate matter can be deposited on the surface of the metal fiber laminate 17, so that the particulate matter is ozone or It can be removed by oxidation with hydroxy radicals.

  Further, the generated ozone or hydroxy radical can oxidize nitrogen oxides or sulfur oxides in the exhaust gas and reform them into harmless gases.

  In addition, since ozone or a hydroxyl radical has a short lifetime, the distance between the ultraviolet ray generating member 18 and the metal fiber laminate 17 can be preferably in the range of 1 mm to 5 mm, particularly preferably 1 mm to 3 mm.

  Next, the action of removing particulate matter by oxidation and the action of reforming exhaust gas will be specifically described.

When vacuum ultraviolet rays having a wavelength of 200 nm or less act on moisture in the exhaust gas, oxygen radicals (.O) and hydroxy radicals (.OH) are generated as shown in Formula 1. When vacuum ultraviolet rays act on oxygen in the exhaust gas, oxygen radicals are generated as shown in Equation 2. The generated oxygen radicals are combined with oxygen to generate ozone (.O ₃ ) as shown in Equation 3.

  The generated hydroxy radicals are oxidized (burned) into carbon dioxide as shown in Formula 4 to be removed by elimination. Further, the generated hydroxy radical oxidizes nitrogen dioxide to form nitric acid radical as shown in Formula 5, and the nitric acid radical reacts with moisture as shown in Formula 6 to be reformed into nitrogen gas.

  On the other hand, the generated ozone oxidizes (combusts) the particulate matter into carbon dioxide as shown in Equation 7 to be eliminated. Further, the generated ozone oxidizes nitrogen dioxide and reforms it into nitrogen pentoxide as shown in Equation 8.

  As described above, ozone or hydroxy radical generated by the action of vacuum ultraviolet rays on moisture or oxygen gas acts on the particulate matter in the exhaust gas to oxidize and remove the particulate matter, and the gas in the exhaust gas. The gas component can be oxidized and reformed by acting on the component.

  As described above, according to the exhaust gas treatment device 10 of the present invention, the metal mesh body 14 is disposed as the positive electrode and the metal structure (metal fiber laminate) 17 is disposed as the negative electrode, and the exhaust gas that has passed through the metal mesh body 14 is disposed. Negative space charges are attached to the particulate matter in the gas, and the particulate matter can be decelerated as it approaches the metal fiber laminate 17. Since the decelerated particulate matter can be in contact with ozone or hydroxy radicals generated by irradiation with vacuum ultraviolet rays of 200 nm or less for a long time, the particulate matter can be efficiently oxidized and removed. In addition, since the metal fiber laminate 17 that passes the gas but captures the particulate matter is used as the metal structure, the particulate matter captured by the metal fiber laminate 17 is also exposed to the generated ozone or hydroxy radical for a long time. Since it can be contacted, the particulate matter can be efficiently oxidized and removed. Furthermore, the gas component in the exhaust gas can be oxidized and reformed into a harmless gas.

(Application examples)
Next, another example (application example) of the exhaust gas processing apparatus according to the present invention will be described with reference to FIG. The exhaust gas processing apparatus 30 includes a processing unit configured in the order of a metal mesh body 14, an ultraviolet ray generating member 18, and a metal fiber laminate (metal structure) 17 from the inlet 12 side toward the outlet 13 side. This is an example in which a plurality of housings 11 are arranged in the axial direction. Here, three processing units are arranged in series, but two processing units may be arranged in series, or four or more processing units may be arranged in series. In the following description, the same components as those in the exhaust gas processing apparatus 10 shown in FIG.

  In this exhaust gas treatment device 30, a unit process constituted by a metal mesh body 14, an ultraviolet ray generating member 18 and a metal structure 17 (17A, 17B, 17C) in this order from the inlet 12 side toward the outlet 13 side. Three units are arranged in series in the axial direction of the housing 11. The housing 11 is preferably composed of a slightly longer hollow tube so that the three unit processing units can be accommodated therein, but the rest is the same as in the case of the exhaust gas processing apparatus 10 shown in FIG. is there. Further, the metal mesh body 14, the ultraviolet ray generating member 18 and the metal structure 17 (17A, 17B, 17C) are the same as those in the exhaust gas treatment apparatus 10 shown in FIG. The decelerating action, the oxidative removal action and the oxidative reforming action by ozone or hydroxy radicals can be executed.

  A voltage is applied from the power supply 21 between the metal mesh body 14 and the metal fiber laminate 17 constituting each processing unit. In each metal mesh body 14, the particulate matter is negatively charged each time, decelerating as it approaches each metal fiber laminate 17, and the deceleration action in each section can be executed.

  The metal fiber laminates 17A, 17B, and 17C may be configured such that the porosity decreases sequentially from the metal fiber laminate 17A located on the upstream side toward the metal fiber laminate 17C located on the downstream side. it can. As an example, the upstream metal fiber laminate 17A may be 85%, the intermediate metal fiber laminate 17B may be 80%, and the downstream metal fiber laminate 17C may be 75%. By carrying out like this, in the metal fiber laminated body 17A located in the most upstream side, a comparatively big particulate matter can be oxidatively removed, and a small particulate matter can be oxidatively removed in order. As a result, particulate matter of various sizes contained in the exhaust gas can be surely oxidized and removed. Further, by increasing the porosity of the metal fiber laminate 17A disposed on the upstream side, the metal fiber laminate 17A can be prevented from being clogged by the accumulated particulate matter.

  According to the exhaust gas processing apparatus 30, by arranging two or more processing units in the axial direction of the housing 11, for example, even when a fine particulate matter cannot be sufficiently oxidized and removed by the first processing unit, Oxidation can be removed by subsequent processing units. Further, even when nitrogen oxide or the like cannot be oxidized and reformed by the first processing unit, it can be oxidized and reformed by the second and subsequent processing units.

[Second Embodiment]
The exhaust gas treatment device 40 according to the second embodiment has the above-described basic configuration. Further, as shown in FIG. 6, (I) a metal mesh body is coated with a plurality of titanium oxide coatings extending in the axial direction of the housing 41. The mesh cylinder 44 is used, and (II) the metal structure is disposed at a position where the hollow portion of the titanium oxide-coated mesh cylinder 44 is interrupted in the middle, so that the exhaust gas in the titanium oxide-coated mesh cylinder 44 is removed. A shielding metal plate 45 that blocks the passage and changes the course in another titanium oxide-coated mesh cylindrical body 44, and (III) an ultraviolet ray generating member is provided at the axial center of the housing 41 and extends in the axial direction. An ultraviolet generation member 48 that generates ultraviolet rays having a wavelength of 400 nm is provided. Reference numeral 49 denotes a power source for applying electric power to the ultraviolet ray generating member 48.

  Specifically, the exhaust gas treatment device 40 shown in FIG. 6 is provided with an ultraviolet ray generating member 48 formed of a plurality of ultraviolet lamps at the axial center position (center portion) of the housing 41. As shown in FIGS. 6 and 8, a titanium oxide-coated mesh cylindrical body 44 is provided adjacent to the inside of the housing 41 at a predetermined interval so as to surround the ultraviolet ray generating member 18. At both ends in the longitudinal direction of the cylindrical body 44 made of titanium oxide-coated mesh, the ultraviolet ray generating member 18 is prevented from slipping out of the housing 41, and holding plates 46 for holding the cylindrical body 44 made of titanium oxide-coated mesh (FIG. 8).

(Housing, inlet, outlet)
The housing 41 only needs to have a length corresponding to the length of the cylindrical body 44 made of titanium oxide-coated mesh, and the rest is the same as that of the exhaust gas treatment apparatus 10 shown in FIG. Omitted.

  A holding plate 46 is provided on the introduction port 42 side and the exhaust port 43 side of the housing 41. The shape of the holding plate 46 is the same as the inner surface shape of the housing 41, and when the inner surface shape of the housing 41 is circular, it is preferably a disk shape (see FIG. 8). A plurality of circular holding holes 47 are formed in the holding plate 46. The holding hole 47 is formed to have substantially the same size as the outer diameter of the titanium oxide-coated mesh cylinder 44, and the titanium oxide-coated mesh cylinder 44 can be inserted from the holding hole 47. The inserted titanium oxide-coated mesh cylindrical body 44 is fixed to the holding plate 46 by a stopper (not shown) such as a screw provided on the holding plate 46.

  In the example of FIG. 8, a holding hole for inserting the ultraviolet ray generating member 18 is not provided at the center of the holding plate 46, but may be provided. A recess for holding the ultraviolet ray generating member 18 at the center may be provided on the inner surface of the holding plate 46. Such holding plates 46 are respectively inserted into the introduction port 42 and the exhaust port 43 of the housing 41, and are attached to the housing 41 so that the peripheral edges thereof are fitted to the inner peripheral surface of the housing 41.

  As in the case of the housing, the material of the holding plate 46 is durable against vacuum ultraviolet rays having a wavelength of 200 nm or less, and is also durable against exhaust gas components such as nitrogen oxide and sulfur oxide. A metal is preferred. As such a metal, steel materials, such as stainless steel, can be mentioned preferably, for example.

  The introduction port 42 and the discharge port 43 are also the same as those in the exhaust gas processing apparatus 10 shown in FIG.

(Titanium oxide coated mesh cylinder)
As shown in FIG. 7, the titanium oxide-coated mesh cylindrical body 44 is a plurality of cylindrical bodies extending in the axial direction of the housing 41, and is cylindrical so that both gaseous components and particulate matter can pass through the exhaust gas. The outer peripheral wall is formed of a titanium oxide-coated mesh. The mesh-like cylindrical body 44 made of titanium oxide is durable against vacuum ultraviolet rays having a wavelength of 200 nm or less, and is also durable against exhaust gas components such as nitrogen oxides and sulfur oxides. As will be described later, the titanium oxide mesh-shaped cylindrical body 44 can generate a photochemical reaction with vacuum ultraviolet rays to generate hydroxy radicals and oxygen radicals from moisture and oxygen.

  The mesh of the cylindrical body 44 made of titanium oxide-coated mesh is a mesh that covers at least titanium oxide on the surface. Specifically, the surface of the mesh made of titanium wire is coated with titanium oxide. The titanium oxide-coated mesh can be obtained by heating a mesh made of titanium wire in a predetermined oxidizing atmosphere. The outer diameter of the titanium wire is not particularly limited, but is about 100 μm to 500 μm, preferably about 100 μm to 200 μm. The thickness of titanium oxide is not particularly limited, but is preferably about 1 μm to 10 μm, and preferably about 1 μm to 2 μm. In addition, the opening of the cylindrical body 44 made of titanium oxide-coated mesh may be of a size that allows passage of particulate matter of about 2 μm, for example.

(Shield metal plate)
The shielding metal plate 45 is provided at a predetermined position in the longitudinal direction (axial direction) inside the cylindrical body 44 made of titanium oxide-coated mesh, at a position where the cylindrical space is shielded midway. The shape of the shielding metal plate 45 is the same disk shape as the inner surface shape of the cylindrical body 44 made of titanium oxide-coated mesh. Such a shielding metal plate 45 functions to prevent the passage of particulate matter in the exhaust gas that travels in the longitudinal direction through the cylindrical body 44 made of titanium oxide-coated mesh. Furthermore, it functions to prevent the passage of gas in the exhaust gas. The path of the exhaust gas containing particulate matter is changed by the shielding metal plate 45, passes through the outer peripheral wall of the titanium oxide-coated mesh cylinder 44, and proceeds into the adjacent titanium oxide-coated mesh cylinder 44. It will be.

  The shielding metal plate 45 is preferably provided at a different position for each titanium oxide-coated mesh cylindrical body 44. By providing the shielding metal plate 45 at different positions, it is possible to change the course of the exhaust gas passing through the titanium oxide-coated mesh cylindrical body 44 at various positions in the housing 41.

  The material of the shielding metal plate 45 is preferably durable against vacuum ultraviolet rays having a wavelength of 200 nm or less, and is also durable against exhaust gas components such as nitrogen oxide and sulfur oxide. As such a metal, steel materials, such as stainless steel, can be mentioned preferably, for example. The thickness of the shielding metal plate 45 is not particularly limited, but may be, for example, about 0.1 mm to 1 mm, preferably about 0.1 mm to 0.2 mm.

(Ultraviolet generating member)
The ultraviolet ray generating member 48 is configured by arranging a plurality of ultraviolet lamps in the longitudinal direction (axial direction) of the central portion of the housing 41. The ultraviolet ray generating member 18 irradiates the titanium oxide-coated mesh cylindrical body 44 with ultraviolet rays, and generates hydroxy radicals and oxygen radicals by a photochemical reaction of the titanium oxide. The ultraviolet ray generating member 18 only needs to emit ultraviolet rays having a wavelength of 300 to 400 nm, and various ultraviolet lamps can be adopted. For example, a high pressure mercury lamp with a wavelength of 380 nm can be mentioned. The ultraviolet ray generating member 18 is connected to a power source 49 provided outside.

(Oxidation removal action and oxidation reforming action)
In the exhaust gas treatment device 40 according to the present invention, the oxidation removal action on the particulate matter and the oxidation reforming action on the exhaust gas will be described in detail.

  The exhaust gas taken in from the introduction port 42 is diverted in the holding holes 47 of the holding plate 46 provided in the housing 41 and is sent to a plurality of titanium oxide-coated mesh cylinders 44. The exhaust gas that has been fed advances in the longitudinal direction of each titanium oxide-coated mesh cylinder 44. The exhaust gas that has traveled through the interior hits a shielding metal plate 45 provided in the cylinder 44 made of titanium oxide-coated mesh, and the progress of the exhaust gas is blocked in the other cylinder 44 made of titanium oxide-coated mesh. . The exhaust gas whose course has been changed passes through the mesh portion of the outer peripheral wall of the titanium oxide-coated mesh cylindrical body 44, passes through the outer peripheral wall of another adjacent titanium oxide-coated mesh cylindrical body 44, and is introduced therein. Is done. Thereafter, the exhaust gas introduced into the adjacent cylinder 44 made of titanium oxide-coated mesh travels downstream until it collides with the shielding metal plate 45 in the cylinder 44 made of titanium oxide-coated mesh.

  Thus, each of the plurality of titanium oxide-coated mesh cylinders 44 having the same diameter is provided adjacent to each other at a predetermined interval in the housing 41, so that the exhaust gas can be changed straightly and vertically and horizontally. Are repeated in the plurality of titanium oxide-coated mesh cylinders 44. As a result, the moving distance of the exhaust gas can be lengthened and contacted with the generated ozone or hydroxy radical for a long time. As a result, it is possible to more efficiently perform oxidation removal of particulate matter in the exhaust gas and oxidation reforming of nitrogen oxide and the like.

  The titanium oxide-coated mesh cylindrical body 44 is irradiated with ultraviolet rays from the ultraviolet ray generating member 18. Titanium oxide irradiated with ultraviolet rays generates hydroxy radicals (.OH radicals) and oxygen radicals from air and oxygen. Oxygen radicals react with oxygen to produce ozone. The hydroxy radicals and ozone thus generated have a strong oxidizing action. Therefore, ozone or hydroxy radicals act on the particulate matter in the exhaust gas to oxidize and remove the particulate matter.

  In addition, harmful gases such as nitrogen oxides and sulfur oxides in the exhaust gas are also oxidized by the ozone or hydroxy radicals and modified into harmless oxides.

  As described above, the exhaust gas passes through the outer peripheral wall of the titanium oxide-coated mesh cylinder 44 a plurality of times before reaching the holding plate 46 on the exhaust port 43 side from the holding plate 46 on the inlet port 42 side. . That is, the exhaust gas travels through the plurality of titanium oxide-coated mesh cylinders 44 without changing the course. Since the titanium oxide-coated mesh generates ozone or hydroxy radicals by photochemical reaction with ultraviolet rays of 300 nm to 400 nm generated from the ultraviolet ray generating member 48, the ozone or hydroxy radicals in the exhaust gas proceeding without changing the course. There is an effect that the particulate matter is oxidized and removed, or nitrogen oxides and the like are oxidized and modified.

(Application examples)
Next, still another example (application example) of the exhaust gas processing apparatus according to the present invention will be described with reference to FIG. This exhaust gas treatment device 50 is the same as the exhaust gas treatment device 40 shown in FIG. 6 except that titanium oxide-coated mesh cylinders 52, 53, and 54 having different diameters are concentrically arranged inside a housing 51. When such titanium oxide-coated mesh cylindrical bodies 52, 53, 54 are provided, the titanium oxide-coated mesh cylindrical body 52 disposed on the outer side and the titanium oxide-coated mesh cylindrical body 53 disposed on the inner side are appropriately disposed. Is provided with a shielding metal plate (not shown). As a result, the exhaust gas that has traveled straight between the outer peripheral walls of the cylinders 52, 53, 54 made of titanium oxide-coated mesh collides with the shielding metal plate, changes its direction, and passes through the mesh formed on the outer peripheral wall. It will be.

  When the exhaust gas whose direction has been changed passes through the outer peripheral walls of the cylinders 52, 53, and 54 made of titanium oxide-coated mesh, ozone or hydroxy radical generated by the photochemical reaction of titanium oxide is caused by particulate matter and gas components in the exhaust gas. As described above, the particulate matter can be oxidized and the gas component can be oxidized and reformed. Since the other configuration is the same as that described in FIG. 6, the description thereof is omitted here.

  As described above, the titanium oxide-coated mesh cylinders 52, 53, and 54 have different diameters and are provided concentrically in the housing. You can go inside. As a result, the distance traveled by the exhaust gas can be lengthened and contacted with the generated ozone or hydroxy radical for a long time, so that oxidation removal of particulate matter in the exhaust gas and oxidation reforming of nitrogen oxides and the like can be further performed. Can be done efficiently.

  As described above, according to the exhaust gas treatment apparatuses 10, 30, 40, and 50 according to the present invention, (i) since a low-power ultraviolet ray generating member is used, unlike the plasma discharge, the apparatus has low power, simplification, and light weight. And can be preferably applied to an internal combustion engine provided in a mobile machine such as an automobile. (ii) Since the particulate matter can be slowed down or the path of the exhaust gas can be lengthened, it can be brought into contact with ozone or a hydroxyl radical for a long time, and oxidation removal and oxidation reforming can be performed efficiently. it can. (iii) Since the titanium oxide in the presence of ultraviolet rays or air is irradiated with ultraviolet rays, the generated ozone or hydroxy radicals are used to efficiently remove particulate matter and oxidize and reform nitrogen oxides, etc. Can do.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Exhaust part 3, 4 Exhaust pipe (muffler)
10, 30 Exhaust gas treatment device 11 Housing 12 Inlet 13 Exhaust 14 Metal mesh body 15 Frame 16 Net (mesh)
17, 17A, 17B, 17C Metal structure (metal fiber laminate)
18 Ultraviolet generating member 19 Light emitting part 20 Base 21 Power source 22 Constant voltage device 23 Battery

40, 50 Exhaust gas treatment device 41, 51 Housing 42 Inlet port 43 Exhaust port 44 Cylindrical body made of titanium oxide coated mesh 45 Metal structure 46 Holding plate 47 Holding hole 48, 55 Ultraviolet generating member 49 Power source 52, 53, 54 Different diameter Cylinder made of titanium oxide coated mesh

Claims (5)

An exhaust gas treatment device for treating exhaust gas containing particulate matter connected to an exhaust pipe of an internal combustion engine,
A housing having a hollow tube structure, an introduction port for taking in exhaust gas into the housing, a metal mesh body through which exhaust gas taken into the housing from the introduction port passes, and an exhaust gas that has passed through the metal mesh body A metal structure that prevents the passage of particulate matter, an ultraviolet ray generating member that generates ozone or hydroxy radicals by irradiating ultraviolet rays toward the metal mesh body and the metal structure, and exhaust gas after being irradiated with ultraviolet rays And an exhaust port for exhausting gas from the housing. The metal structure is a metal fiber laminate that passes gas but captures particulate matter;
The ultraviolet ray generating member is a member that generates ultraviolet rays having a wavelength of 200 nm or less,
A power source for applying a voltage having the metal mesh body as a positive electrode and the metal structure as a negative electrode;
The particulate matter in the exhaust gas that has passed through the metal mesh body is attached with a negative space charge by the application of the voltage, and the particulate matter is decelerated as it approaches the metal fiber laminate. Exhaust gas treatment equipment.   2. A plurality of processing units configured in the order of the metal mesh body, the ultraviolet ray generating member, and the metal structure from the introduction port side toward the discharge port side are arranged in the axial direction of the housing. The exhaust gas treatment apparatus according to 1 or 2. The metal mesh body is a plurality of titanium oxide-coated mesh cylinders extending in the axial direction of the housing,
The metal structure is disposed at a position where the hollow portion of the cylindrical body made of titanium oxide-coated mesh is interrupted in the middle to block the passage of exhaust gas in the cylindrical body made of titanium oxide-coated mesh, and another titanium oxide-coated mesh It is a shielding metal plate that changes the course in the cylindrical body,
2. The exhaust gas processing apparatus according to claim 1, wherein the ultraviolet ray generating member is a member that is provided at an axial center position of the housing and extends in the axial direction and generates ultraviolet rays having a wavelength of 300 nm to 400 nm. The titanium oxide-coated mesh cylindrical body has the same diameter, and is provided adjacent to the housing at a predetermined interval, or
The exhaust gas treatment apparatus according to claim 4, wherein the titanium oxide-coated mesh cylindrical body has a different diameter and is provided concentrically in the housing.

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