JP2009127442A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device capable of minimizing the deterioration of trapping efficiency, removing PMs, enhancing durability, and regenerating electrodes, without raising a temperature of a dust collecting filter device. <P>SOLUTION: The exhaust emission control device 50 includes the dust collecting filter device 2 arranged along the inside of an outer shell 1 which is provided with a dust collecting electrode and a dust collecting filter layer; an exhaust gas passage 7 formed inside the dust collecting filter device 2 and through which exhaust gas including PMs flow; and discharge electrodes 40 installed in a state that tips thereof are separated from each other in a direction across the exhaust gas passage 7 and generate an ion wind 30 for inducing and forming a secondary flow in a direction perpendicular to an exhaust gas flow between them and the dust collecting filter device 2 when an voltage is applied. In this case, a heater 10 to which an oxidation catalyst 11 is applied is provided between the dust collecting filter device 2 and the outer shell 1. PMs in the exhaust gas collected by the dust collecting filter device 2 are burned by heating the heater 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification apparatus that removes particulate matter (particulate matter, hereinafter referred to as PM) contained in exhaust gas of a diesel engine, a gasoline engine, or the like.

FIG. 6 is a schematic cross-sectional view showing an example of an electric dust collector disclosed in Patent Document 1 (WO2005 / 021161).
In FIG. 6, a dust collector 100 includes a cylindrical outer shell 1, a discharge electrode 40 including a discharge electrode main portion 4 and a discharge electrode discharge portion 3, a dust collection filter device including a dust collection electrode and a dust collection filter layer. 2 are provided. The discharge electrode 40 is connected to the high voltage generator 20 through the high-voltage conductor 5a and the insulator 5. The insulator 5 is accommodated in the insulator chamber 6.

  The outer shell 1 is formed in a cylindrical shape, and the inside thereof is an exhaust gas passage 7 through which exhaust gas containing PM flows, and the exhaust gas passes through the exhaust gas passage 7 along the discharge electrode 40 as shown by arrows in FIG. It comes to flow. For this reason, the discharge electrode 40 includes a discharge electrode main portion 4 extending in the direction of the exhaust gas flow in the center of the exhaust gas passage 7, and the dust collection filter device 2 across the exhaust gas passage 7 from the discharge electrode main portion 4. It is comprised from the several discharge electrode discharge part 3 formed in the stab shape extended toward the side.

  In such a dust collector 100, when a high voltage from the high voltage generator 20 is applied to the discharge electrode 40 via the high-voltage conductor 5a, dust is collected from the discharge electrode main portion 4 and the plurality of discharge electrode discharge portions 3. An ion wind induced by the ions jumping toward the dust collection electrode of the filter device 2 is generated. As a result, most of the PM contained in the exhaust gas flow passes through the dust collection electrode, and the PM is guided together with the gas to the dust collection filter layer disposed outside the dust collection electrode. Most of it is collected and becomes purified gas.

WO2005 / 021161

In general, a diesel particulate filter (hereinafter referred to as DPF), which is a black smoke removal device, is used to remove PM in exhaust gas from a diesel engine or the like and perform purification treatment. However, this DPF has the following problems.
That is, over time, in the DPF, pressure loss due to filter clogging increases, and unless clogging removal and regeneration are performed periodically, the filter is clogged and a load is applied to the exhaust side, increasing the fuel consumption rate. At the same time, the engine output will be reduced. Moreover, if the filter is further clogged, there is a possibility that the engine will stop.

Therefore, as a prior art, an electric dust collector that can process PM with a low pressure loss, such as Patent Document 1, is employed. However, this electric dust collector has the following problems regarding electrode regeneration.
That is, in the electric dust collector 100, the PM collected by the dust filter device 2 needs to be periodically removed to regenerate the dust filter device 2. As a means for this reproduction, the following method is usually used.
A heater is provided in the porous portion of the dust collecting filter device 2, and the collected PM is burned and incinerated by heating the heater to regenerate the electrode. However, in order to burn the PM, the temperature is raised to 500 ° C or higher. There is a problem in the durability of the device. Moreover, when such PM adheres to the dust collection electrode or the dust collection filter layer of the dust collection filter device 2, a reduction in collection efficiency is unavoidable. As a result, the surface of the insulator 5 located on the downstream side is contaminated with residual PM over time, insulation cannot be maintained, and a predetermined voltage cannot be stably applied.

  The present invention has been made in view of such a situation, and the object thereof is to remove PM without increasing the temperature of the dust collection filter device and minimizing the reduction in collection efficiency. Therefore, an object of the present invention is to provide an exhaust gas purifying apparatus capable of improving durability and regenerating an electrode.

  In order to solve the above-described problems of the prior art, the present invention includes a cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer. An exhaust gas passage formed inside the dust collecting filter device through which exhaust gas containing particulate matter flows and a tip of the exhaust gas passage in the direction crossing the exhaust gas passage are separated from each other and a voltage is applied. An exhaust gas purification apparatus comprising a discharge electrode that generates an ion wind that induces and forms a secondary flow in a direction orthogonal to the exhaust gas flow, sometimes with the dust collection filter device, wherein the dust collection filter device and the outer A heater coated with an oxidation catalyst is provided between the shells and is configured to burn particulate matter in the exhaust gas collected by the dust collection filter device by heating the heater. That.

  In the present invention, the dust collection filter device is preferably a cylindrical body having a circular or polygonal cross section.

  The present invention also includes a cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer, and is formed inside the dust collecting filter device. An exhaust gas passage through which exhaust gas containing particulate matter flows, and the dust collection filter device when a voltage is applied between the exhaust gas passage and the exhaust gas passage installed in a direction across the exhaust gas passage. In the exhaust gas purifying apparatus comprising a discharge electrode for generating an ionic wind that induces a secondary flow in a direction orthogonal to the exhaust gas flow, a space portion is provided between the dust collecting filter device and the outer shell. An ejection nozzle that ejects compressed air from the upstream side to the downstream side of the dust collection filter device is provided in the space portion.

  In the present invention, the dust collection filter device is a cylindrical body having a circular or polygonal cross-sectional shape, and a plurality of the ejection nozzles are arranged at intervals in the circumferential direction of the space portion. Is preferred.

  Furthermore, the present invention includes a cylindrical outer shell, a dust collecting filter device disposed along the outer shell and including a dust collecting electrode and a dust collecting filter layer, and formed inside the dust collecting filter device. An exhaust gas passage through which exhaust gas containing particulate matter flows, and the dust collection filter device when a voltage is applied between the exhaust gas passage and the exhaust gas passage installed in a direction across the exhaust gas passage. In the exhaust gas purification apparatus comprising a discharge electrode for generating an ionic wind that induces and forms a secondary flow in a direction orthogonal to the exhaust gas flow, the dust collection filter layer is constituted by a heater coated with an oxidation catalyst, By heating the heater, the particulate matter in the exhaust gas collected by the dust collection filter layer is combusted.

  In the present invention, the dust collection filter device is preferably a cylindrical body having a circular or polygonal cross section.

As described above, the exhaust gas purifying apparatus according to the present invention includes a cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer, and the dust collecting device. An exhaust gas passage that is formed inside the filter device and through which exhaust gas containing particulate matter flows, and is installed in the exhaust gas passage in a state of being separated from each other in a direction across the exhaust gas passage, and when a voltage is applied, A discharge electrode for generating an ionic wind that induces a secondary flow in a direction orthogonal to the exhaust gas flow between the dust collection filter device and the dust collection filter device; In the meantime, a heater coated with an oxidation catalyst is provided, and by heating the heater, particulate matter in the exhaust gas collected by the dust collecting filter device is combusted. , The dust collection Filter apparatus, since the cross-sectional shape is circular or polygonal cylindrical body, by the action of the oxidation catalyst coated on the surface of the heater, and next to NO ₂ and NO in the exhaust gas is oxidized, the NO ₂ is PM When contacted, the combustion start temperature becomes 250 to 350 ° C.

  Therefore, it is possible to completely burn PM at a temperature lower by about 250 to 150 ° C. compared to the prior art that requires a high temperature of 500 ° C. or higher to burn PM. As a result, the durability of the apparatus is improved, and PM can be completely burned even at a low temperature. Therefore, the remaining PM is small, a reduction in collection efficiency can be prevented, and the electrode can be regenerated.

  Further, according to the present invention, in the exhaust gas purification apparatus, a space portion is provided between the dust collection filter device and the outer shell, and the space portion has an upstream side to a downstream side of the dust collection filter device. An ejection nozzle that ejects compressed air toward the surface is provided. Specifically, the dust collection filter device is a cylindrical body having a circular or polygonal cross-sectional shape, and the ejection nozzle is disposed in the space portion. Since a plurality of nozzles are arranged at intervals in the circumferential direction, PM adhering to the dust collection filter device can be easily removed by simply ejecting compressed air from a general-purpose ejection nozzle, and dust collection is possible without burning. The electrode of the filter device can be regenerated.

Furthermore, the present invention provides the exhaust gas purification apparatus, wherein the dust collection filter layer is constituted by a heater coated with an oxidation catalyst, and the heater is heated to thereby collect the dust in the exhaust gas collected by the dust collection filter layer. The particulate filter device is configured to burn particulate matter. Specifically, the dust collection filter device is a cylindrical body having a circular or polygonal cross-sectional shape, so that the dust collection filter layer is formed on the surface of the heater constituting the dust collection filter layer. By the action of the applied oxidation catalyst, NO in the exhaust gas is oxidized to NO ₂ , and when this NO ₂ comes into contact with PM, the combustion start temperature becomes 250 to 350 ° C. Therefore, as in the case of the above-described invention, PM can be completely burned at a temperature lower by about 250 to 150 ° C. as compared with the prior art that requires a high temperature of 500 ° C. or higher to burn PM. As a result, the durability of the apparatus is improved, and PM can be completely burned even at a low temperature. Therefore, the remaining PM is small, a reduction in collection efficiency can be prevented, and the electrode can be regenerated.

  Hereinafter, an exhaust gas purifying apparatus according to the present invention will be described in detail based on embodiments thereof with reference to the drawings.

[First Embodiment]
FIG. 1A is a schematic cross-sectional view showing an exhaust gas purification apparatus according to the first embodiment of the present invention, and FIG. 1B is an enlarged view of a Z portion in FIG. FIG. 2 is a view as seen from an arrow A in FIG. 1 showing a first example of the dust collection filter device, and FIG. 3 is a view as seen from an arrow A in FIG. 1 showing a second example of the dust collection filter device.
1 to 3, the exhaust gas purification apparatus 50 of the present embodiment includes a cylindrical outer shell 1, a discharge electrode 40 including a discharge electrode main portion 4 and a discharge electrode discharge portion 3, a dust collection electrode 2 a, and dust collection. And a dust collecting filter device 2 including a filter layer 2b. The discharge electrode 40 is connected to a high voltage generator (not shown) (see FIG. 6) via the high voltage conductor 5 a and the insulator 5 arranged in the insulator chamber 6. The dust collection electrode 2a is formed of a conductive material such as a conductive wire mesh having an opening through which PM passes, and the dust collection filter layer 2b is a material having air permeability such as a laminated wire mesh and porous ceramics. It is formed with.

The outer shell 1 is formed in a cylindrical shape that is disposed sideways. Inside the outer shell 1 is an exhaust gas passage 7 through which exhaust gas containing PM flows as shown by an arrow, and a discharge electrode 40 is disposed at the center of the exhaust gas passage 7. The discharge electrode 40 is located at the center of the exhaust gas passage 7 and extends along the axial direction of the exhaust gas passage 7, and the dust collecting filter crosses the exhaust gas passage 7 from the discharge electrode main portion 4. It is comprised from the several discharge electrode discharge part 3 formed in the stab shape extended toward the apparatus 2 side.
As shown in FIG. 1, these discharge electrode discharge portions 3 are provided at regular intervals along the axial direction of the discharge electrode main portion 4 from the upstream side to the downstream side. At the same position in the axial direction, as shown in FIG. 2 and FIG. 3, the outer peripheral surface of the discharge electrode main portion 4 is radially arranged with a predetermined interval with the tips thereof being separated from each other. In the present embodiment, four discharge electrode discharge portions 3 are provided at the same position, and are arranged at intervals of 90 degrees.

  In such an exhaust gas purifying device 50, a high voltage from a high voltage generator (not shown) is applied to the discharge electrode 40 through the high voltage conductor 5a, whereby the discharge electrode main portion 4 and the plurality of discharge electrode discharge portions 3 are applied. To the dust collection electrode 2a of the dust collection filter device 2 located inside the outer shell 1, ions are emitted, and an ion wind 30 induced by the ions is generated. By this ion wind 30, most of the PM contained in the exhaust gas flow passes through the dust collection electrode 2a and is guided to the dust collection filter layer 2b disposed outside the dust collection electrode 2a together with the gas. In 2b, most of the PM is collected and led to the downstream side as purified gas.

  Further, in the exhaust gas purifying apparatus 50 according to the first embodiment of the present invention, a power supply (not shown) is provided between the outer periphery of the dust collecting filter device 2 and the inner periphery of the outer shell 1 as shown in FIGS. A heater 10 connected to is provided. For this reason, the dust collection filter device 2 is a cylindrical body having a circular cross-sectional shape, and is disposed with a space between the inner periphery of the outer shell 1. Alternatively, as shown in FIG. 3, the dust collection filter device 2 is a cylindrical body having a polygonal cross section (in this embodiment, a quadrangle), and between the inner periphery of the outer shell 1 except for the corners. It is arranged to form a space.

On the other hand, the heater 10 is formed using a rod-like member having an axial length substantially the same as that of the dust collection filter device 2, and a plurality of heaters 10 are arranged along the outer periphery of the dust collection filter device 2. ing. An oxidation catalyst 11 is applied to the outer surface of the heater 10. Here, the function of the oxidation catalyst 11 is that NO in exhaust gas is oxidized to NO ₂ by catalytic action of platinum, palladium, etc., and when this NO ₂ comes into contact with PM, the combustion temperature in PM is 250 to 350. It becomes a low temperature of ℃.

  Thus, in the exhaust gas purifying apparatus 50 of the first embodiment, the dust collecting filter is between the dust collecting filter device 2 having a circular or polygonal cross-sectional shape and the cylindrical outer shell 1. A plurality of heaters 10 are provided at intervals along the outer periphery of the apparatus 2, and the oxidation catalyst 11 is applied to the surfaces of the heaters 10. By heating the heaters 10, the dust collection filter apparatus 2 is provided. Since the PM collected in step 1 is burned, the PM burns at a low temperature of 250 to 350 ° C. by the action of the oxidation catalyst 11 applied to the surface of the heater 10.

  Therefore, the PM in the exhaust gas can be completely burned at a temperature as low as about 250 to 150 ° C. as compared with the prior art that requires a high temperature of 500 ° C. or higher to burn the PM. As a result, the durability of the exhaust gas purifying device 50 is improved, PM can be completely burned even at a low temperature, and the collection efficiency can be prevented from being lowered, so that a purified gas with little residual PM can be obtained.

[Second Embodiment]
FIG. 4 is a schematic cross-sectional view showing an exhaust gas purification apparatus according to the second embodiment of the present invention.
In FIG. 4, in the exhaust gas purifying apparatus 50 of the present embodiment, the cross-sectional shape is between the outer periphery of the dust collection filter device 2 which is a circular or polygonal cylindrical body and the inner periphery of the cylindrical outer shell 1. A space portion 13 is provided. A plurality of ejection nozzles 14 configured to eject compressed air 14 a from the upstream side to the downstream side of the dust collection filter device 2 are provided on the upstream side of the space portion 13.
Further, these ejection nozzles 14 are arranged at regular intervals in the circumferential direction of the space 13, and are connected to a compressed air source 18 via a distribution pipe 15, a supply pipe 16 and an on-off valve 17. . The distribution pipe 15 and the supply pipe 16 are attached to the outer shell 1 by a connecting member 19.
Other configurations are the same as those of the first embodiment, and the same members are denoted by the same reference numerals.

  Thus, in the exhaust gas purification apparatus 50 of the second embodiment of the present invention, the space portion 13 is provided between the dust collection filter device 2 and the outer shell 1, and a plurality of ejection nozzles 14 are provided in the space portion 13. Since it is arranged at a certain interval in the circumferential direction, the compressed air 14a from the compressed air source 18 is sent to the jet nozzle 14 through the supply pipe 16 and the distribution pipe 15 by opening the on-off valve 17, From the ejection nozzle 14, the dust is uniformly ejected into the space 13 from the upstream side to the downstream side of the dust collection filter device 2. Therefore, according to the exhaust gas purifying apparatus 50 of the present embodiment, the PM collected by the dust collection filter device 2 can be easily removed at a low temperature without burning, and the dust collection filter device 2 can be quickly cleaned. Thus, the dust collecting filter device 2 can be regenerated.

[Third Embodiment]
FIG. 5 is a schematic cross-sectional view showing an exhaust gas purifying apparatus according to a third embodiment of the present invention.
In FIG. 5, the exhaust gas purifying apparatus 50 of this embodiment includes a dust collecting filter device 21 including a dust collecting electrode 21a and a dust collecting filter layer 21b. The dust collecting filter layer 21b is a heater coated with an oxidation catalyst. It is configured. Other configurations are the same as those of the first embodiment, and the same members are denoted by the same reference numerals.

  As described above, in the exhaust gas purification device 50 according to the third embodiment, the dust collection filter layer 21b of the dust collection filter device 21 is composed of the heater coated with the oxidation catalyst, and the heater is heated to collect the dust. Since the PM in the exhaust gas collected by the dust filter layer 21b is burned, the PM burns at a low temperature of 250 to 350 ° C. by the action of the oxidation catalyst applied to the surface of the heater, and has a simpler structure. The same effect as the first embodiment can be obtained.

While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various changes and modifications can be made based on the technical idea of the present invention.
For example, in the embodiment described above, the oxidation catalyst 11 is applied only to the heater 10, but it can also be applied to the dust collection filter layer of the dust collection filter device 2 and the inner peripheral surface of the outer shell 1. .

(A) is a schematic sectional drawing which shows the exhaust gas purification apparatus which concerns on 1st Embodiment of this invention, (B) is the Z section enlarged view in (A). It is an A arrow line view of Drawing 1 showing the 1st example of an oxidation catalyst concerning a 1st embodiment of the present invention. It is A arrow directional view of FIG. 1 which shows the 2nd example of the oxidation catalyst which concerns on 1st Embodiment of this invention. It is a schematic sectional drawing which shows the exhaust gas purification apparatus which concerns on 2nd Embodiment of this invention. It is a schematic sectional drawing which shows the exhaust gas purification apparatus which concerns on 3rd Embodiment of this invention. It is a schematic sectional drawing which shows the example of the conventional electric dust collector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer shell 2 Dust collection filter apparatus 2a Dust collection electrode 2b Dust collection filter layer 3 Discharge electrode discharge part 4 Discharge electrode main part 5a High-pressure conducting wire 7 Exhaust gas passage 10 Heater 11 Oxidation catalyst 13 Space part 14 Injection nozzle 14a Compressed air 15 Distribution pipe DESCRIPTION OF SYMBOLS 16 Supply pipe 17 On-off valve 18 Compressed air source 21 Dust collection filter apparatus 21a Dust collection electrode 21b Dust collection filter layer 30 Ion wind 40 Discharge electrode 50 Exhaust gas purification apparatus

Claims (6)

A cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer, and is formed inside the dust collecting filter device and includes particulate matter. The exhaust gas passage through which the exhaust gas flows and the exhaust gas passage orthogonal to the exhaust gas flow between the dust collection filter device when a voltage is applied are installed in the exhaust gas passage in a direction crossing the exhaust gas passage. In an exhaust gas purification apparatus comprising a discharge electrode that generates an ionic wind that induces and forms a secondary flow in the direction of
A heater coated with an oxidation catalyst is provided between the dust collection filter device and the outer shell, and the particulate matter in the exhaust gas collected by the dust collection filter device is heated by heating the heater. An exhaust gas purification apparatus configured to burn.   The exhaust gas purifying device according to claim 1, wherein the dust collecting filter device is a cylindrical body having a circular or polygonal cross section. A cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer, and is formed inside the dust collecting filter device and includes particulate matter. The exhaust gas passage through which the exhaust gas flows and the exhaust gas passage orthogonal to the exhaust gas flow between the dust collection filter device when a voltage is applied are installed in the exhaust gas passage in a direction crossing the exhaust gas passage. In an exhaust gas purification apparatus comprising a discharge electrode that generates an ionic wind that induces and forms a secondary flow in the direction of
A space portion is provided between the dust collection filter device and the outer shell, and a jet nozzle that jets compressed air from the upstream side to the downstream side of the dust collection filter device is provided in the space portion. An exhaust gas purifying apparatus characterized by that.   The dust collection filter device is a cylindrical body having a circular or polygonal cross-sectional shape, and a plurality of the ejection nozzles are arranged at intervals in the circumferential direction of the space portion. The exhaust gas purification device according to claim 3. A cylindrical outer shell, a dust collecting filter device that is disposed along the outer shell and includes a dust collecting electrode and a dust collecting filter layer, and is formed inside the dust collecting filter device and includes particulate matter. The exhaust gas passage through which the exhaust gas flows and the exhaust gas passage orthogonal to the exhaust gas flow between the dust collection filter device when a voltage is applied are installed in the exhaust gas passage in a direction crossing the exhaust gas passage. In an exhaust gas purification apparatus comprising a discharge electrode that generates an ionic wind that induces and forms a secondary flow in the direction of
The dust collection filter layer is composed of a heater coated with an oxidation catalyst, and is configured to burn particulate matter in the exhaust gas collected by the dust collection filter layer by heating the heater. An exhaust gas purification apparatus characterized by that. 6. The exhaust gas purifying apparatus according to claim 5, wherein the dust collecting filter device is a cylindrical body having a circular or polygonal cross section.

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