JP2011206743A - Gas treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further increase overall gas treatment capacity by generating plasma even in a space between adjacent gas treatment units, and to reduce cost and time for manufacture and assembly by reducing the number of components.SOLUTION: Ground electrodes 9-1 and 9-2 of the gas treatment units GU1 and GU2 are integrated with each other and used as a common electrode 9. A voltage of positive polarity is applied to a high-voltage electrode 8-1, a voltage of negative polarity is applied to a high-voltage electrode 8-2, a voltage of positive polarity is applied to a high-voltage electrode 10-1, and a voltage of negative polarity is applied to a high-voltage electrode 10-2, of the gas treatment units GU1 and GU2, respectively. As a result, a large potential difference is generated between the facing high-voltage electrodes, and plasma is generated even in the space between the adjacent gas treatment units to treat gas. Since ground electrodes are integrated (used in common) between the adjacent gas treatment units, the number of components can be reduced.

Description

  The present invention relates to a gas processing apparatus that purifies harmful gas contained in a gas to be processed.

  2. Description of the Related Art Conventionally, a technique for purifying harmful gas contained in exhaust gas by creating a plasma state by performing high voltage discharge in the exhaust gas is known. In recent years, this technology is being applied to a purification device for purifying factory exhaust and an air purifier for purifying indoor air for the purpose of deodorization.

  Plasma that is in a thermally non-equilibrium state, that is, in which the electron temperature is much higher than the temperature of the gas or ion (non-equilibrium plasma (hereinafter simply referred to as plasma)) is the ion or radical produced by electron collision. Promotes a chemical reaction that does not occur at room temperature, and is considered useful in hazardous gas treatment as a medium that can efficiently remove or decompose harmful gases. The key to practical use is to improve the energy efficiency during processing and to convert it into a completely safe product after processing with plasma.

In general, plasma at atmospheric pressure is generated by gas discharge or electron beam. There are nitrogen oxides (NOx), sulfur oxides (SOx), chlorofluorocarbons, CO ₂ , volatile organic solvents (VOC), etc. that are currently being considered for application. Above all, NOx is contained in the exhaust gas of a car, so that it needs to be put into practical use immediately.

The phenomenon in discharge plasma (plasma generated by gas discharge) in NOx removal is that ions and radicals generated primarily by electron collision cause an initial reaction, and N ₂ , H ₂ O, It is thought that it is converted into each particle such as NH ₄ NO ₃ .

Further, when the harmful gas is, for example, acetaldehyde or formaldehyde, the harmful gas is converted into CO ₂ and H ₂ O by passing plasma. In this case, ozone (O ₃ ) is generated as a by-product.

  FIG. 3 illustrates a main part of a conventional gas processing apparatus using discharge plasma (see, for example, Patent Document 1). In the figure, reference numeral 1 denotes a duct (ventilation path) through which a processing target gas (air containing toxic gas) GS flows. Inside the duct 1, a discharge electrode 2 and a ground electrode 3 are arranged along the direction in which the processing target gas GS passes. Are disposed alternately, and a honeycomb structure 4 having a large number of through-holes 4a called cells is disposed between the electrodes 2 and 3. Reference numeral 5 denotes a high voltage power source. The honeycomb structure 4 is formed of an insulator such as ceramics, and Patent Document 2 also has an example of its use.

  The discharge electrode 2 is formed of a metal mesh, a fine wire, a needle-like body, or the like. Each discharge electrode 2 is connected to the + pole of the high voltage power supply 5 by a conducting wire 6. The ground electrode 3 is formed of a metallic mesh or the like. Each ground electrode 3 is connected to the negative pole of the high voltage power supply 5 by a conducting wire 7.

  In this gas processing apparatus, the gas GS to be processed is caused to flow through the duct 1, and a high voltage (several kV to several tens kV) from the high voltage power supply 5 is applied between the discharge electrode 2 and the ground electrode 3. Thereby, plasma is generated in the through-holes 4a of the honeycomb structures 4, and harmful gases contained in the processing target gas GS are decomposed into harmless substances by ions and radicals generated in the plasma.

However, the gas processing apparatus having such a configuration has the following problems.
(1) Although a large number of honeycomb structures 4 are provided, a technique for generating uniform plasma without variations has not been established, and variations in the performance of the honeycomb structures 4 occur. For example, impedance values may be different even in the same honeycomb structure 4, and impedance values may be different in one honeycomb structure 4, for example, at the top and bottom thereof, so that uniform plasma can be generated as a whole. Therefore, the gas processing capacity becomes unstable. Further, since plasma is generated only through the through holes 4a, the amount of plasma generated is small and the gas processing capacity is low.

  (2) The honeycomb structure 4 has a characteristic of low impedance when moisture is absorbed and high impedance when dried. When the honeycomb structure 4 becomes low impedance, the flowing current increases and the discharge electrode 2 and the ground electrode 3 When the high voltage value applied between them decreases and the honeycomb structure 4 becomes high impedance, the flowing current decreases and the high voltage value applied between the discharge electrode 2 and the ground electrode 3 increases. The high voltage power supply 5 that can obtain a high voltage value that can secure a desired plasma generation amount with respect to such a change in the high voltage value is very expensive including the man-hours required for its design.

(3) Since the discharge electrode 2 and the ground electrode 3 are provided for each of the honeycomb structures 4, the number of parts is large, the structure is complicated, and the cost is high.
(4) Since the honeycomb structure 4 is disposed in the duct 1 along the passing direction of the gas GS to be treated (direction from the inlet to the outlet of the duct 1), the direction orthogonal to the gas flow of the honeycomb structure 4 The dimension of is longer and the dimension parallel to the gas flow is shorter. For this reason, when the flow rate of the gas flow is high, the time during which the gas GS to be processed is exposed to the plasma inside the honeycomb structure 4 is short, and the gas processing capacity is reduced.

  Therefore, the present applicant has proposed a gas processing apparatus as shown in FIG. 4 as a solution to the problems of the conventional gas processing apparatus described above (see Patent Document 3). In this gas processing apparatus, a plurality of honeycomb structures having a large number of through holes (round holes) 4a are provided along the direction orthogonal to the passing direction of the processing target gas GS from the inlet to the outlet of the duct 1 4 (4-1 to 4-4) are arranged.

  In this example, the honeycomb structures 4-1 and 4-2 constitute a first honeycomb structure group 4A, and the honeycomb structures 4-1 and 4 positioned at both ends of the first honeycomb structure group 4A. -2 is arranged on the outside of the electrode 8 as the first electrode, and the electrode 9 is arranged as the second electrode. The honeycomb structures 4-3 and 4-4 constitute a second honeycomb structure group 4B, and the honeycomb structures 4-3 and 4-4 positioned at both ends of the second honeycomb structure group 4B. The electrode 9 is disposed as the first electrode, and the electrode 10 is disposed as the second electrode.

  In the first honeycomb structure group 4A, the high voltage from the high voltage power source 5 is applied between the first electrode 8 and the second electrode 9 by using the electrode 8 as a high voltage electrode and the electrode 9 as a ground electrode. In addition, in the second honeycomb structure group 4B, between the first electrode 9 and the second electrode 10, the electrode 9 is a ground electrode and the electrode 10 is a high-voltage electrode. Is applied to the through holes 4a of the honeycomb structure 4 and the space 11 (11-1, 11-2) between the honeycomb structures 4 to generate plasma. Thereby, the harmful gas contained in the gas GS to be processed is decomposed into harmless substances by ions and radicals generated in the plasma. The electrodes 8, 9, and 10 are made of metal mesh so that the processing target gas GS can pass therethrough.

JP 2000-140562 A JP 2001-276561 A JP 2008-194670 A

  In the gas processing apparatus shown in FIG. 4, the gas processing capacity is improved as compared with the gas processing apparatus shown in FIG. 3, but in order to further improve the gas processing capacity, this gas processing apparatus is used as one gas processing apparatus. It is conceivable that a plurality of units are installed in the passing direction of the processing target gas GS. FIG. 5 shows an example in which two gas processing units are installed in the passing direction of the processing target gas GS.

  In this case, the high voltage electrodes 8-1 and 8-2 of the adjacent gas processing units GU1 and GU2 face each other, the ground electrodes 9-1 and 9-2 face each other, and the high voltage electrodes 10-1 and 10- 2 does not generate a potential difference between the opposing electrodes, so that plasma is hardly generated in the space between the gas processing units GU1 and GU2 (there is no generation of plasma in the areas AR1, AR2 and AR3). The overall gas processing capacity remains at the sum of the individual gas processing units GU1, GU2.

  Further, when N sets of such gas processing units GU are installed, there is a problem that the number of necessary electrodes and honeycomb structures becomes N times, the number of parts increases, and it takes time to assemble the gas processing apparatus.

  The present invention has been made to solve such a problem. The object of the present invention is to generate plasma even in the space between adjacent gas processing units to further increase the overall gas processing capacity and to provide components. An object of the present invention is to provide a gas processing apparatus capable of reducing the number of points to reduce the cost and time of manufacturing and assembly.

  In order to achieve such an object, the present invention provides a large number of penetrations through which the processing target gas passes and is arranged along a direction orthogonal to the passing direction of the processing target gas from the inlet to the outlet of the ventilation path. A plurality of honeycomb structures having holes and a plurality of adjacent honeycomb structures among the plurality of honeycomb structures constitute a group of honeycomb structures, and each honeycomb structure group has a honeycomb structure positioned at both ends thereof. A high voltage is individually applied between the ground electrode and the high voltage electrode arranged on the outside, and the ground electrode and the high voltage electrode of each honeycomb structure group, and plasma is generated in the through holes of the honeycomb structure and the spaces between the honeycomb structures. In a gas processing apparatus in which a plurality of gas processing units each having a high voltage source to be generated are installed along the direction in which the gas to be processed passes, the granulation between adjacent gas processing units With the electrodes are opposed and integral with, it is obtained by a high-pressure electrodes of the gas processing unit and adjacent to face, and those facing different polarity of the applied high voltage of the high voltage electrode from each other.

  According to this invention, the number of ground electrodes is reduced by integrating (commonizing) the ground electrodes of adjacent gas processing units. Thereby, the number of parts can be reduced, and the time required for assembling the gas processing apparatus can also be reduced. Further, the high voltage electrodes of the adjacent gas processing units are opposed to each other, and the high voltage applied polarities of the opposed high voltage electrodes are different from each other. For example, when the first electrode of the honeycomb structure group of one adjacent gas processing unit is a positive high-voltage electrode and the second electrode is a ground electrode, the honeycomb structure group of the other adjacent gas processing unit is The first electrode is a negative high voltage electrode, and the second electrode is a ground electrode. As a result, a large potential difference is generated between the high voltage electrodes facing each other, and plasma is generated in the space between the adjacent gas processing units to perform gas processing.

  According to the present invention, the ground electrodes of adjacent gas processing units are opposed and integrated, and the high voltage electrodes of adjacent gas processing units are opposed to each other. Because of the difference between the two, the large potential difference occurs between the high voltage electrodes facing each other, plasma is generated in the space between adjacent gas processing units, and gas processing is performed. In addition to the above, the gas processing capacity by the plasma generated between the gas processing units is added, and the overall gas processing capacity is further increased. Further, the ground electrodes of the adjacent gas processing units are integrated (shared), the number of ground electrodes is reduced, the number of parts is reduced, and the cost and time of manufacturing and assembly can be reduced.

It is a figure which shows the principal part of one Embodiment (Embodiment 1) of the gas processing apparatus which concerns on this invention. It is a figure which shows the principal part of other embodiment (Embodiment 2) of the gas processing apparatus which concerns on this invention. It is a figure which illustrates the principal part of the conventional gas processing apparatus using discharge plasma. It is a figure which shows the principal part of the gas processing apparatus shown by patent document 3. FIG. It is a figure which shows the example which installed two the gas processing apparatuses shown by patent document 3 in the passage direction of process target gas as a gas processing unit.

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

  FIG. 1 is a diagram showing a main part of an embodiment (Embodiment 1) of a gas processing apparatus according to the present invention. 5, the same reference numerals as those in FIG. 5 denote the same or equivalent components as those described with reference to FIG. 5, and the description thereof will be omitted.

  Also in this gas processing apparatus, the gas processing units GU1 and GU2 are connected to the duct 1 along the passing direction of the processing target gas GS (the direction from the inlet to the outlet of the duct 1) in the same manner as the gas processing apparatus shown in FIG. Placed in

  However, in this embodiment, the second electrode 9-1 of the first honeycomb structure group 4A of the gas processing unit GU1 and the second electrode 9- of the first honeycomb structure group 4C of the gas processing unit GU2 are used. 2 is integrated into a common electrode 9. In addition, the honeycomb structure 4-12 of the first honeycomb structure group 4A of the gas processing unit GU1 and the honeycomb structure 4-22 of the first honeycomb structure group 4C of the gas processing unit GU2 are integrated to form a common A honeycomb structure 4-2 is formed. Further, the honeycomb structure 4-13 of the second honeycomb structure group 4B of the gas processing unit GU1 and the honeycomb structure 4-23 of the second honeycomb structure group 4D of the gas processing unit GU2 are integrated into a common structure. A honeycomb structure 4-3 is provided.

  Further, between the first electrode 8-1 and the common electrode 9 of the first honeycomb structure group 4A of the gas processing unit GU1, the electrode 8-1 is a positive high voltage electrode, and the common electrode 9 is a ground electrode. A high voltage from the high voltage power source 5-1 is applied, and the common electrode 9 is a ground electrode between the common electrode 9-1 and the second electrode 10-1 of the second honeycomb structure group 4B. A high voltage from the high voltage power source 5-1 is applied with the electrode 10-1 as a positive high voltage electrode.

  Further, between the first electrode 8-2 and the common electrode 9 of the first honeycomb structure group 4C of the gas processing unit GU2, the electrode 8-2 is a negative high voltage electrode, and the common electrode 9 is a ground electrode. A high voltage from the high voltage power source 5-2 is applied, and the common electrode 9 is connected to the ground electrode and the electrode 10 between the common electrode 9 and the second electrode 10-2 of the second honeycomb structure group 4D. −2 is a negative high voltage electrode, and a high voltage from the high voltage power source 5-2 is applied.

  That is, in this embodiment, the ground electrodes 9-1 and 9-2 of the adjacent gas processing units GU1 and GU2 are integrated, and the positive high voltage electrode 8-1 and the negative high voltage electrode 8-2 are integrated. The positive high-voltage electrode 10-1 and the negative high-voltage electrode 10-2 are opposed to each other. As a result, a large potential difference is generated between the opposing high voltage electrodes, plasma is generated in the space between adjacent gas processing units (plasma is also generated in the areas AR1 and AR2), and gas processing is performed. In addition, the number of ground electrodes is reduced, the number of parts is reduced, and manufacturing / assembly costs and time are reduced.

  As described above, in the first embodiment, the cost and time for manufacturing and assembling are reduced, and the gas generated by the plasma generated between the gas processing units is added to the sum of the individual gas processing capacities of the gas processing units GU1 and GU2. The processing capacity is added, and the overall gas processing capacity is further increased.

[Embodiment 2]
FIG. 2 shows a main part of another embodiment (Embodiment 2) of the gas treatment apparatus according to the present invention. In this gas processing apparatus, the first electrode 8-1 of the first honeycomb structure group 4A of the gas processing unit GU1 and the second electrode 8-2 of the first honeycomb structure group 4C of the gas processing unit GU2 Are integrated into a common electrode 8.

  Further, the second electrode 10-1 of the second honeycomb structure group 4B of the gas processing unit GU1 and the second electrode 10-2 of the second honeycomb structure group 4D of the gas processing unit GU2 are integrated, The common electrode 10 is used.

  In addition, the honeycomb structure 4-11 of the first honeycomb structure group 4A of the gas processing unit GU1 and the honeycomb structure 4-21 of the first honeycomb structure group 4C of the gas processing unit GU2 are integrated into a common A honeycomb structure 4-2 is formed.

  Further, the honeycomb structure 4-14 of the second honeycomb structure group 4B of the gas processing unit GU1 and the honeycomb structure 4-24 of the second honeycomb structure group 4D of the gas processing unit GU2 are integrated, and a common A honeycomb structure 4-4 is provided.

  Further, between the common electrode 8 and the second electrode 9-1 of the first honeycomb structure group 4A of the gas processing unit GU1, the common electrode 8 is a ground electrode, and the electrode 9-1 is a negative high voltage electrode. A high voltage from the high voltage power source 5-2 is applied, and the electrode 9-1 is a negative high voltage electrode between the first electrode 9-1 and the common electrode 10 of the second honeycomb structure group 4B. The high voltage from the high voltage power source 5-2 is applied using the common electrode 10 as a ground electrode.

  Further, between the common electrode 8 and the second electrode 9-2 of the first honeycomb structure group 4C of the gas processing unit GU2, the common electrode 8 is a ground electrode, and the electrode 9-2 is a positive high voltage electrode. A high voltage from the high voltage power source 5-1 is applied, and the electrode 9-2 is a positive high voltage electrode between the first electrode 9-2 and the common electrode 10 of the second honeycomb structure group 4D. The high voltage from the high voltage power source 5-1 is applied using the common electrode 10 as a ground electrode.

  That is, in this embodiment, while integrating the ground electrodes 8-1 and 8-2 of the adjacent gas processing units GU1 and GU2, and integrating the ground electrodes 10-1 and 10-2, The negative high voltage electrode 9-1 and the positive high voltage electrode 9-2 are opposed to each other. As a result, a large potential difference is generated between the high-voltage electrodes facing each other, plasma is generated in the space between the adjacent gas processing units (plasma is also generated in the area AR3), and gas processing is performed. In addition, the number of ground electrodes is reduced, the number of parts is reduced, and manufacturing / assembly costs and time are reduced.

  As described above, also in the second embodiment, manufacturing and assembly costs and time are reduced, and the gas generated by the plasma generated between the gas processing units is added to the sum of the individual gas processing capacities of the gas processing units GU1 and GU2. The processing capacity is added, and the overall gas processing capacity is further increased.

  In the first embodiment, the honeycomb structures 4-12, 4-22 and 4-13, 4-23 in contact with the ground electrode 9 are integrated between the gas processing units GU1 and GU2. In Embodiment 2, the honeycomb structures 4-11, 4-21 and 4-14, 4-24 in contact with the ground electrodes 8 and 10 are integrated between the gas processing units GU1 and GU2, but they are not necessarily integrated. You don't have to.

  As in the first and second embodiments, the honeycomb structure in contact with the ground electrode is integrated between the gas processing units GU1 and GU2, thereby reducing the number of honeycomb structures and the number of parts, and integrating the ground electrode. Along with this, the time and cost required for assembling the gas processing apparatus can be greatly reduced.

  In the first embodiment, the number of ground electrodes is smaller than that in the second embodiment. However, since the number of positive and negative high voltage electrodes can be increased, the space between the honeycomb structures in contact with the opposed positive and negative high voltage electrodes is large. Therefore, the opportunity for generating plasma between adjacent gas processing units increases, and the increase in gas processing capacity increases.

  In the second embodiment, since the ground electrode can be disposed outside the outermost honeycomb structure in the direction orthogonal to the passing direction of the processing target gas, the design is facilitated. That is, it is easy to ground, easy to manufacture, and easy to ensure safety.

  In the second embodiment, in the gas processing unit GU1, the gaps G1, G2 between the honeycomb structures 4 are gradually narrowed from the upstream side to the downstream side in the passing direction of the processing target gas GS. The gaps G1 and G2 between the bodies 4 are widened on the upstream side where the plasma generation conditions are good and narrowed on the downstream side where the plasma generation conditions are bad, and the gas generation capacity is balanced between the upstream and downstream plasma generation states. Is stable.

  In the first and second embodiments described above, the honeycomb structure 4 may have a catalyst function for decomposing ozone, and a catalyst for decomposing ozone may be provided at a downstream position in the passing direction of the processing target gas GS. It may be.

  Moreover, in Embodiment 1 and 2 mentioned above, although the number of gas processing units was two, you may make it increase the number further. In the first and second embodiments, the number of honeycomb structure groups in the gas treatment unit is not limited to two, but may be two or more, and the number may be increased. Further, the number of honeycomb structures constituting the honeycomb structure group is not limited to two.

  Further, in the first and second embodiments described above, a large amount of ozone may be generated as a by-product and used as an ozone generator.

The gas processing apparatus of the present invention can also be applied to so-called reforming for generating a hydrogen-containing gas from hydrocarbons or the like for the purpose of efficiently generating hydrogen used in a fuel cell or the like. For example, in the case of octane (substance relatively close to the average molecular weight of gasoline) C ₈ H ₁₈ , when supplied to this gas treatment device, the chemical reaction represented by the following formula (1) is promoted, and as a result, hydrogen gas is efficiently generated. can do.
C ₈ H ₁₈ + 8H ₂ O + 4 (O ₂ + 4N ₂ ) → 8CO ₂ + 17H ₂ + 16N ₂ ... (1)

  DESCRIPTION OF SYMBOLS 1 ... Duct (ventilation path), 4 (4-1-4-4, 4-11-4-14, 4-21-4-24) ... Honeycomb structure, 4a ... Through-hole (cell), 4A-4D ... Honeycomb structure group, 5-1, 5-2 ... High voltage power supply, 8 (8-1, 8-2), 9 (9-1, 9-2), 10 (10-1, 10-2) ... Electrode, 11 ... Space, G (G1 to G4) ... Interval, GS ... Process target gas, GU (GU1, GU2) ... Gas treatment unit, AR1, AR2, AR3 ... Area.

Claims (4)

A plurality of honeycomb structures having a large number of through holes arranged at intervals along a direction orthogonal to the passage direction of the processing target gas from the inlet to the outlet of the ventilation path, and through which the processing target gas passes;
A plurality of adjacent honeycomb structures among the plurality of honeycomb structures are made into one group of honeycomb structures, and a ground electrode and a high pressure are arranged outside the honeycomb structures positioned at both ends of each honeycomb structure group. Electrodes,
A high voltage source that individually applies a high voltage between the ground electrode and the high-voltage electrode of each honeycomb structure group to generate plasma in the through-holes of the honeycomb structure and the space between the honeycomb structures. In a gas processing apparatus in which a plurality of gas processing units are installed along the direction of passage of the gas to be processed,
The ground electrode of each gas processing unit is integrated with the ground electrodes of adjacent gas processing units facing each other.
The high-pressure electrode of each gas processing unit is such that the high-voltage electrodes of adjacent gas processing units face each other, and the high-voltage application polarities of the opposing high-pressure electrodes are different from each other. The gas treatment device according to claim 1, wherein
The honeycomb structure of each of the gas processing units has a honeycomb structure in which the ground electrodes of adjacent gas processing units are arranged opposite to each other and integrated. In the gas treatment device according to claim 1 or 2,
The gas processing apparatus, wherein the high-pressure electrode is disposed outside the honeycomb structure disposed at an outermost end in a direction orthogonal to a passing direction of the processing target gas from the inlet to the outlet of the ventilation path. In the gas treatment device according to claim 1 or 2,
The gas processing apparatus, wherein the ground electrode is disposed outside the honeycomb structure disposed at an outermost end in a direction orthogonal to a passing direction of the processing target gas from the inlet to the outlet of the ventilation path.

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