JP2011206704A - 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.SOLUTION: A high voltage from a high voltage power source 5 is applied between a first electrode 8-1 as a ground electrode, and a second electrode 9-1 as a high voltage electrode, of a gas treatment unit GU1. The high voltage from the high voltage power source 5 is applied between a first electrode 8-2 as a high voltage electrode, and a second electrode 9-2 as a ground electrode, of another gas treatment unit GU2. As a result, a potential difference is generated between the facing electrodes, and plasma is generated even in the space between the adjacent gas treatment units (plasma is generated even in areas AR1 and AR2) to treat gas in the space (in the areas).

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 type 1 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, intervals G (G1 to G3) are provided along a direction orthogonal to the passing direction of the processing target gas GS from the inlet to the outlet of the duct 1, and a large number of through holes (round holes) 4a are formed. A plurality of honeycomb structures 4 (4-1 to 4-4) are arranged.

  Reference numeral 8 denotes a first electrode disposed outside the honeycomb structure 4-1 located at one end in a direction orthogonal to the passing direction of the processing target gas GS among the honeycomb structures 4-1 to 4-4. Reference numeral 9 denotes a second electrode disposed outside the honeycomb structure 4-4 located at the other end of the honeycomb structures 4-1 to 4-4 in the direction orthogonal to the passing direction of the processing target gas GS. The metal mesh is used so that the processing target gas GS passes through.

  By applying a high voltage from a high voltage power source (high voltage source) 5 between the first electrode 8 and the second electrode 9 using the electrode 8 as a high voltage electrode and the electrode 9 as a ground electrode, Plasma is generated in the space 11 (11-1 to 11-3) between the through hole 4a of the structure 4 and the honeycomb structure 4. 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.

  Further, the present applicant has proposed a type 2 gas processing apparatus as shown in FIG. 5 (see Patent Document 4). In this gas treatment device, the honeycomb structure 4-1 and 4-2 constitute a first honeycomb structure group 4A, and the honeycomb structure 4-1 located at both ends of the first honeycomb structure group 4A. And the electrode 8 is arrange | positioned as a 1st electrode on the outer side of 4-2, and the electrode 9 is arrange | positioned as a 2nd 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.

JP 2000-140562 A JP 2001-276561 A JP 2008-194669 A JP 2008-194670 A

  In the above-described type 1 and type 2 gas processing apparatuses, 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, the type 1 and type 2 gas processing apparatuses are improved. It is conceivable that a plurality of gas processing apparatuses are installed in the direction of passage of the processing target gas GS as one gas processing unit. FIG. 6 shows an example in which two type 1 gas processing units are installed in the passing direction of the processing target gas GS. FIG. 7 shows an example in which two type 2 gas processing units are installed in the passing direction of the processing target gas GS.

  In this case, in the example shown in FIG. 6, the high voltage electrodes 8-1 and 8-2 of the adjacent gas processing units GU1 and GU2 face each other, and the ground electrodes 9-1 and 9-2 face each other. Since there is no potential difference between the opposing electrodes, plasma is not easily generated in the space between the gas processing units GU1 and GU2 (there is no generation of plasma in the areas AR1 and AR2). It remains in the sum of the gas processing units GU1, GU2.

  In the example shown in FIG. 7, 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 pressure electrodes GU1 and GU2 face each other. Since the electrodes 10-1 and 10-2 face each other and no potential difference is generated between the electrodes facing each other, plasma is hardly generated in the space between the gas processing units GU1 and GU2 (plasma generation in the areas AR1, AR2 and AR3) In this case, the total gas processing capacity is limited to the sum of the individual gas processing units GU1 and GU2.

  The present invention has been made to solve such problems, and the object of the present invention is to generate plasma even in the space between adjacent gas processing units, thereby further improving the overall gas processing capacity. Is to provide a simple gas treatment apparatus.

  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, a first electrode disposed on the outer side of the honeycomb structure disposed at one end of the plurality of honeycomb structures in a direction orthogonal to the passing direction of the gas to be treated; A second electrode disposed outside the honeycomb structure disposed at the other end of the honeycomb structure in a direction orthogonal to the passage direction of the gas to be processed, and the first electrode and the second electrode Gas processing in which a plurality of gas processing units are provided along the direction of passage of the gas to be processed, with a high voltage applied between them to generate plasma in the through holes of the honeycomb structure and plasma in the space between the honeycomb structures Equipment There are, in which the first electrode and the second electrode of the gas processing unit and adjacent to face, and that different polarity of the applied high voltage of the electrodes of the opposing.

  Further, a plurality of honeycomb structures having a plurality of through-holes arranged at intervals along a direction orthogonal to the direction of passage of the processing target gas from the inlet to the outlet of the ventilation passage and having a plurality of through holes through which the processing target gas passes, A plurality of adjacent honeycomb structures among the honeycomb structures are defined as one group of honeycomb structures, and the first and second honeycomb structures are arranged outside the honeycomb structures positioned at both ends of each honeycomb structure group. High voltage source for generating plasma in the through holes of the honeycomb structure and the space between the honeycomb structures by individually applying a high voltage between the electrode and the first electrode and the second electrode of each honeycomb structure group In the gas processing apparatus in which a plurality of gas processing units each including the gas processing unit are installed along the passage direction of the gas to be processed, the first electrode and the second electrode of each honeycomb structure group of the adjacent gas processing units It is opposed, and is obtained by a different from each other the polarity of the applied high voltage of the electrodes of the opposing.

  According to the present invention, when a plurality of type 1 gas processing units are installed along the direction in which the gas to be processed passes, the first electrode and the second electrode of the adjacent type 1 gas processing units are The opposite polarities of the high-voltage application polarities of the opposing electrodes are different from each other. For example, when the first electrode of one adjacent gas processing unit is a high-voltage electrode and the second electrode is a ground electrode, the first electrode of the other adjacent gas processing unit is the ground electrode, and the second electrode These electrodes are high voltage electrodes. As a result, a potential difference is generated between the opposing electrodes, and plasma is generated in the space between adjacent gas processing units to perform gas processing.

  Further, when a plurality of type 2 gas processing units are installed along the passage direction of the gas to be processed, the first electrode and the second electrode of each honeycomb structure group of the adjacent type 2 gas processing unit The electrodes face each other, and the high voltage application polarities of the facing 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 high-voltage electrode and the second electrode is a ground electrode, the first structure of the honeycomb structure group of the other adjacent gas processing unit is the first electrode. The electrode is a ground electrode, and the second electrode is a high voltage electrode. As a result, a potential difference is generated between the opposing electrodes, and plasma is generated in the space between adjacent gas processing units to perform gas processing.

  According to the present invention, the first electrode and the second electrode of the adjacent gas processing units are opposed to each other, and the high voltage application polarities of the opposed electrodes are different from each other. The first electrode and the second electrode of each honeycomb structure group of the gas treatment unit are opposed to each other, and the high voltage applied polarities of the opposed electrodes are different from each other. As a result, plasma is generated in the space between adjacent gas processing units and gas processing is performed, and the sum of the gas processing capacities of the gas processing units is added to the gas processing capacity by the plasma generated between the gas processing units. As a result, the overall gas processing capacity is further increased.

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 (type 1 gas processing unit) shown by patent document 3. FIG. It is a figure which shows the principal part of the gas processing apparatus (type 2 gas processing unit) shown by patent document 4. FIG. It is a figure which shows the example which installed two conventional type 1 gas processing units in the passage direction of process target gas. It is a figure which shows the example which installed two conventional type 2 gas processing units in the passage direction of process target gas.

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

[Embodiment 1 (Type 1)]
FIG. 1 is a diagram showing a main part of an embodiment (Embodiment 1) of a gas processing apparatus according to the present invention. In FIG. 6, the same reference numerals as those in FIG. 6 denote the same or equivalent components as those described with reference to FIG.

  In this gas processing apparatus, as in the gas processing apparatus shown in FIG. 6, the type 1 gas processing units GU1 and GU2 are arranged along the passing direction of the processing target gas GS (direction from the inlet of the duct 1 to the outlet). Is placed in the duct 1

  However, in this embodiment, the electrode 8-1 is a ground electrode and the electrode 9-1 is a high-voltage electrode between the first electrode 8-1 and the second electrode 9-1 of the gas processing unit GU1, A high voltage from the high voltage power supply 5 is applied. Further, between the first electrode 8-2 and the second electrode 9-2 of the gas processing unit GU2, the electrode 8-2 is a high voltage electrode, and the electrode 9-2 is a ground electrode. A high voltage is applied.

  That is, in this embodiment, the ground electrode 8-1 and the high voltage electrode 8-2 of the adjacent gas processing units GU1 and GU2 are opposed to each other, and the high voltage electrode 9-1 and the ground electrode 9-2 are opposed to each other. Yes. As a result, a potential difference is generated between the opposing 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 this manner, in the first embodiment, the gas processing capability 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, and the overall gas processing capability is further increased. It will increase.

[Embodiment 2 (Type 2)]
FIG. 2 is a view showing a main part of another embodiment (Embodiment 2) of the gas treatment apparatus according to the present invention. In this figure, the same reference numerals as those in FIG. 7 denote the same or equivalent components as those described with reference to FIG.

  In this gas processing apparatus, as in the gas processing apparatus shown in FIG. 7, the type 2 gas processing units GU1 and GU2 are arranged along the passing direction of the processing target gas GS (direction from the inlet of the duct 1 to the outlet). Is placed in the duct 1

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

  Further, between the first electrode 8-2 and the second electrode 9-2 of the first honeycomb structure group 4C of the gas processing unit GU2, the electrode 8-2 is a high-voltage electrode, and the electrode 9-2 is a ground. As an electrode, a high voltage from the high voltage power source 5 is applied, and the electrode 9-2 is interposed between the first electrode 9-2 and the second electrode 10-2 of the second honeycomb structure group 4D. Is a ground electrode and the electrode 10-2 is a high voltage electrode, and a high voltage from the high voltage power source 5 is applied.

  That is, in this embodiment, the ground electrode 8-1 and the high voltage electrode 8-2 of the adjacent gas processing units GU1 and GU2 are opposed to each other, and the high voltage electrode 9-1 and the ground electrode 9-2 are opposed to each other. The ground electrode 10-1 and the high-voltage electrode 10-2 are opposed to each other. As a result, a potential difference is generated between the opposing electrodes, plasma is generated in the space between adjacent gas processing units (plasma is also generated in the areas AR1, AR2, and AR3), and gas processing is performed.

  As described above, also in the second embodiment, the gas processing capacity 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, and the overall gas processing capacity is further increased. It will increase.

  Since the gas processing apparatus of the second embodiment has more electrode pairs facing each other between the adjacent gas processing units GU1 and GU2 than the gas processing apparatus of the first embodiment, plasma is generated between the gas processing units. Spatial area is wide and gas processing capacity is greatly increased.

  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 embodiment, the number of honeycomb structures in the gas treatment unit is not limited to four, but may be two or more, and the number may be increased. In the second embodiment, the number of honeycomb structure groups in the gas treatment unit is not limited to two, and the number may be further increased. Further, the number of honeycomb structures in 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 (4-11-4-14, 4-21-4-24) ... Honeycomb structure, 4a ... Through-hole (cell), 4A-4D ... Honeycomb structure group, 5 ... High voltage power supply, 8-1, 8-2, 9-1, 9-2, 10-1, 10-2 ... electrode, 11 ... space, G (G1-G6) ... interval, GS ... gas to be processed, GU (GU1, GU2) ... gas processing unit, AR1, AR2, AR3 ... area.

Claims (2)

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 first electrode disposed on the outer side of the honeycomb structure disposed at one end of the plurality of honeycomb structures in a direction perpendicular to the direction of passage of the gas to be treated;
A second electrode disposed on the outside of the honeycomb structure disposed at the other end of the plurality of honeycomb structures in a direction perpendicular to the direction of passage of the gas to be treated;
A gas processing unit comprising a high voltage source for applying a high voltage between the first electrode and the second electrode to generate plasma in the through hole of the honeycomb structure and the space between the honeycomb structures In the gas processing apparatus in which a plurality of the gas to be processed is installed along the passage direction of the processing target gas,
The first electrode and the second electrode of each gas processing unit are such that the first electrode and the second electrode of the adjacent gas processing units are opposed to each other, and the high voltage applied polarities of the opposing electrodes are mutually opposite. A gas processing device characterized by being different. 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 regarded as a group of honeycomb structures, and each of the honeycomb structures is disposed outside the honeycomb structures positioned at both ends thereof. Two electrodes;
A high voltage source for generating a plasma in a through hole of the honeycomb structure and a space between the honeycomb structures by individually applying a high voltage between the first electrode and the second electrode of each honeycomb structure group In a gas processing apparatus in which a plurality of gas processing units comprising:
The first electrode and the second electrode of each honeycomb structure group of each gas processing unit are opposed to each other between the first electrode and the second electrode of each honeycomb structure group of the adjacent gas processing unit, and A gas treatment apparatus, wherein the opposing electrodes have different high-voltage application polarities.

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