JP2008029994A - Ventilation gas cleaning apparatus and its cleaning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ventilation gas cleaning apparatus which realizes regeneration of an adsorbing part and surely cleans a ventilation gas without carrying out a troubling operation control. <P>SOLUTION: The ventilation gas cleaning apparatus has an electric charging part 11 which introduces the ventilation gas (X) coexisting with oxygen and oxidizes NO, which is a constituent component of NO<SB>x</SB>contained in the ventilation gas by electric discharging treatment, the adsorbing part 12, which adsorption removes the produced NO<SB>2</SB>to discharge the clean gas cleaned, a reduction gas supplying apparatus 16 which is arranged on a bypass pipe passage 15 arranged over the electric discharging part and the adsorbing part to produce the reduction gas without oxygen, and a switch controlling means 17a, 17b, 18a, 18b, 21, 22 which introduces the ventilation gas (X) and the reduction gas (Y) in turn to the electric discharging part 11 by selecting a gas discharging passage and a reduction gas passage, and reduction decomposes a harmful gas, which is adsorbed on the adsorbing part by electric discharging treatment due to the electric discharging part in introducing of the reduction gas (Y), to produce a harmless gas, while circulating it through the reduction gas supplying apparatus 16, to regenerate the adsorbing part 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ventilation gas purification apparatus and purification method for purifying a ventilation gas containing harmful substances, and in particular, a normal temperature / low concentration such as ventilation gas for tunnels and underground parking lots, roadside exhaust gas at intersections with many vehicles, etc. The present invention relates to a ventilation gas purification device for purifying ventilation gas containing harmful substances and a purification method thereof.

  In recent years, environmental pollution due to acid rain and the like has become a problem, and along with this, nitrogen oxides (hereinafter referred to as NOx) contained in ventilation gas in tunnels and underground parking lots, roadside exhaust gas at intersections with many vehicles, etc. ) And other harmful substances have been increasingly regulated.

  However, the ventilation gas including the current roadside exhaust gas is air having a normal temperature. As a result, the NOx purification catalyst in combustion exhaust gas generally used conventionally cannot be activated because the gas temperature is low, and therefore cannot be used for the purification of the ventilation gas described above.

  Thus, conventionally, two purification methods have been proposed mainly as methods for removing NOx and the like contained in ventilation gas in the presence of oxygen at room temperature.

As one of the purification methods, a dry NOx adsorption / removal method is used, in which NOx (components are nitrogen monoxide NO and nitrogen dioxide NO ₂ ) in the ventilation gas is adsorbed and removed by an adsorbent. In particular, since the NO 2 in NOx _has a property of easily adsorbed, it is possible to easily adsorb and remove NO ₂ in the ventilation gas. In this NOx adsorption removal method, the NOx removal performance can be maintained by exchanging a new adsorbent before the adsorption saturation of NO ₂ .

However, NOx in the ventilation gas is usually composed of about 90% of NO and the remaining 10% of NO ₂ , so that removal efficiency as NOx is poor only by adsorption removal of NO _{2 by} the adsorbent.

Therefore, in this dry NOx adsorption / removal method, ozone O ₃ is added to the ventilation gas before it is adsorbed by the adsorbent to convert NO into NO ₂ , thereby increasing the amount of NOx removed by the adsorbent.

Also, the dry NOx adsorption removal method is a state where the used adsorbent that has sufficiently adsorbed NO ₂ is once transported to another regeneration plant, and then subjected to high-temperature heat treatment, chemical cleaning, etc. so that it can be reused. A method of reproducing and newly reusing is considered (see Patent Document 1).

As another purification method, a wet NOx absorption and removal method in which NOx is absorbed and removed by an alkaline solution is used. This wet NOx absorption and removal method is a method of absorbing and removing NOx which is an acidic gas by spraying an alkali solution into a ventilation gas or sending a ventilation gas into an alkali solution and causing it to bubble (Patent Document 2). reference).
JP-A-8-24579 (FIG. 1) JP-A-6-99030 (FIG. 1)

  By the way, in the purification method using the dry NOx adsorption / removal method as described above or the wet NOx absorption / removal method, the adsorbent can be used relatively easily, and the NOx is absorbed in the alkaline solution in the atmosphere. It is being put into practical use because it does not come out.

However, the dry NOx adsorption / removal method requires a new regeneration process for the adsorbent by the regeneration plant and the replacement process for the adsorbent before the adsorption saturation of NO ₂ , so that operation management and maintenance are complicated and costly. There is a problem.

  In addition, since the wet NOx absorption and removal method is a wet process, a new water distribution treatment facility for the NOx absorption liquid is required, and problems such as operation management of the water distribution treatment facility, equipment cost, and an increase in installation space arise. Come.

  The present invention has been made in view of the above circumstances, realizes regeneration processing of the adsorption unit with a simple configuration, and reliably purifies ventilation gas containing harmful substances without performing stable and complicated operation management over a long period of time. An object of the present invention is to provide a ventilation gas purification device and a purification method thereof.

(1) In order to solve the above-mentioned problem, the ventilation gas purification apparatus according to the present invention is a constituent component of NOx that is provided on the gas discharge path of the ventilation gas coexisting with oxygen and is contained in the ventilation gas by discharge treatment. a discharge unit for NO and by oxidizing to generate NO _2, the discharge portion of the NO ₂ produced is adsorbed removed by a suction unit to discharge the cleaned purge gas, across the discharge portion and the suction portion A reductive gas supply device that generates a reductive gas that does not contain oxygen and is provided on the reductive gas flow path provided, and the ventilation gas and the reductive gas are alternately selected by selecting the gas discharge path and the reductive gas flow path. Introducing into the discharge part, NO ₂ which is a harmful substance adsorbed in the adsorption part by the discharge treatment by the discharge part when the reducing gas is introduced into the reducing gas supply device while reducing and decomposing it into harmless gas Through And a switching control unit that circulates and regenerates the adsorption unit.

In addition, the electrode configuration of the discharge portion includes a first conductor electrode, a second conductor electrode facing the first conductor electrode, and a dielectric covering at least one of the conductor electrodes. When the distance between the first conductor electrode and the second conductor electrode is d (cm) and the absolute value of the applied peak voltage between the first and second conductor electrodes is Vp (kv), the distance average electric field strength E = Based on Vp / d, it is preferable that the distance average electric field intensity E is set so as to satisfy E> 40 (kv / d). The reducing gas produced by the reducing gas supply device is preferably N ₂ containing no oxygen.

(2) Further, the ventilation gas purification apparatus according to the present invention is provided with a NOx concentration sensor in the gas discharge path connected to the inlet side of the discharge part, in addition to the configuration of the above item (1), As the switching control means, the NOx amount measured by the NOx concentration sensor at the time of introduction of the ventilation gas into the discharge portion is integrated, and this integrated NOx amount reaches a predetermined amount before the adsorption saturation of the adsorption portion. Sometimes, the reducing gas flow path is selected, and the reducing gas is introduced from the reducing gas supply device into the discharge section.

  Moreover, if a heating means is provided in the adsorption part or the reducing gas flow path, harmful substances adsorbed on the adsorption part can be separated.

(3) Further, in the ventilation gas purification method according to the present invention, a discharge treatment is performed on the ventilation gas coexisting with oxygen in the discharge section, and NO, which is a constituent component of NOx in the ventilation gas, is oxidized to NO2. NOx generated by this discharge step is adsorbed and removed by the adsorption unit, and the purified gas is discharged, and the amount of NOx is integrated when the ventilation gas is introduced into the discharge unit Then, it is determined whether or not the accumulated NOx amount has reached a prescribed amount before the adsorption saturation of the adsorption portion, and the accumulated NOx amount is reduced to the prescribed amount before the adsorption saturation of the adsorption portion. Switch to a gas supply system, introduce a reducing gas that does not contain oxygen from the reducing gas supply system into the discharge part during discharge treatment, and regenerate the adsorption part while reducing and decomposing harmful substances adsorbed on the adsorption part Play A method and a management step.

  ADVANTAGE OF THE INVENTION According to this invention, the ventilation | gas_gas purification apparatus which can implement | achieve the regeneration process of an adsorption | suction part with a simple structure, can purify the ventilation gas containing a toxic substance reliably for a long time, and without performing complicated operation management, and its A purification method can be provided.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing an embodiment of a ventilation gas purifying apparatus according to the present invention.
The ventilation gas purification apparatus 1 purifies harmful substances such as NOx (nitrogen oxide) contained in the ventilation gas (X) coexisting with oxygen, and purifies the ventilation gas (X) and discharges it. It is installed at an appropriate location in the discharge path 2. Here, the ventilation gas (X) is a ventilation gas including tunnels and underground parking lots, exhaust gas along roads at intersections with many vehicles, etc. Gas.

  The ventilation gas purification apparatus 1 is arranged in the order of the discharge part 11 and the adsorption part 12 from the upstream side of the gas discharge path 2, and a high-voltage cable line 13 is supplied to the discharge part 11 in order to supply a desired discharge voltage. The discharge power supply 14 is connected.

The discharge unit 11 has a function of generating NO ₂ by oxidizing NO, which is a constituent of NOx, which is a harmful substance, by performing a discharge process on the ventilation gas (X) flowing in from the gas discharge path 2. Internally, as shown in FIG. 2, the conductor electrode 11a and the opposing conductor electrode 11b opposed to the conductor electrode 11a are arranged at a predetermined distance. The electrode configuration of the discharge part 11 will be described later.

  The discharge power source 14 applies a desired voltage to the conductor electrode 11a and the counter conductor electrode 11b accommodated in the discharge part 11 while inverting the positive / negative polarity, thereby providing electric power necessary for the discharge process of the discharge part 11. Supply. For example, the counter conductor electrode 11b that constitutes the discharge unit 11 is set to a zero potential, and is applied to the conductor electrode 11a alternately with alternating polarity from + V to -V and from -V to + V. As V, for example, a discharge voltage of 5 kv to 10 kv is used.

That is, the discharge unit 11 generates NO ₂ by oxidizing NO when passing through the conductor electrode 11a and the counter conductor electrode 11b during the discharge process in which the supply of the discharge voltage is supplied. Introduce.

The adsorption unit 12 efficiently adsorbs and supplements NO ₂ generated in the discharge unit 11, takes out the purified gas (Z) purified as a result, and connects the gas discharge path 2 connected to the outlet side of the adsorption unit 12. To the outside. As the adsorbent of the adsorbing portion 12, granular materials such as zeolite, noble metal, activated carbon, alkali metal, alkaline earth metal, activated alumina, silica, and manganese oxide are laminated and used. Of these adsorbents, zeolite and activated alumina are particularly desirable.

  Further, the ventilation gas purification apparatus 1 is connected to a bypass pipe (reducing gas flow path) 15 so as to straddle the discharge section 11 and the adsorption section 12, and the bypass pipe 15 is provided with a reducing gas supply device 16. Yes. The reducing gas supply device 16 introduces the reducing gas (Y) into the discharge unit 11 during the discharge process, and reduces and decomposes harmful substances adsorbed on the adsorption unit 12 by the effect of the discharge process, while the discharge unit 11 and the adsorption unit By circulating through the part 12, the harmful substance is further reduced and decomposed to regenerate the adsorption part 12.

  In order to introduce the ventilation gas (X) and the reducing gas (Y) into the discharge part 11 by alternately switching the gas discharge path 2 and the bypass pipe 15, the gas discharge path 2 and the bypass pipe 15 are respectively provided at predetermined positions of the gas discharge path 2 and the bypass pipe 15. Switching valves 17a, 17b and 18a, 18b are attached.

2A to 2C are diagrams showing detailed electrode configuration examples of the discharge unit 11 shown in FIG.
In the discharge section 11 shown in FIG. 2A, rod-shaped (round bars, square bars) conductor electrodes 11a and counter conductor electrodes 11b are alternately arranged at a desired interval. For example, with respect to the two conductor electrodes 11a and 11a, three counter conductor electrodes 11b, 11b, and so on form a line at an intermediate position between the two conductor electrodes 11a and 11a and a predetermined position outside the conductor electrodes 11a and 11a. 11b is arranged. A dielectric 11c is covered on at least one of the conductor electrode 11a and the counter conductor electrode 11b. The reason for covering the conductor electrode 11a or the counter conductor electrode 11b with the dielectric 11c is to ensure the stability of discharge. The purpose is to eliminate biased and unstable concentrated arc discharge.

  By adopting such an electrode arrangement configuration, a space in which the conductor electrode 11a and the counter conductor electrode 11b are partitioned through the dielectric 11c is formed, and this space portion is a ventilation gas (X) or a reducing gas (Y). It becomes this flow path. And the adsorption | suction part 12 is installed in the downstream of a gas flow path.

  The discharge part 11 shown in FIG. 2 (b) is provided with a plate-like conductor electrode 11a instead of the rod-like conductor electrode 11a, and the other configuration is the same as FIG. 2 (a).

  The discharge part 11 shown in FIG.2 (c) is the structure which covered both the conductor electrode 11a and the opposing conductor electrode 11b with the dielectric material 11c.

Next, the operation of the ventilation gas purification apparatus configured as described above will be described.
The ventilation gas purifying apparatus 1 opens the switching valves 17a and 17b and closes the switching valves 18a and 18b, and from the discharge power supply 14 to each conductor electrode 11a and each counter conductor electrode 11b in the discharge unit 11, A predetermined discharge voltage is applied by alternately switching between positive and negative polarities, and a discharge treatment is performed between each pair of conductor electrode 11a and each counter conductor electrode 11b.

At this time, when the ventilation gas (X) is introduced into the discharge part 11 through the gas discharge path 2, NO which is a constituent of NOx, which is a harmful substance contained in the ventilation gas (X), is oxidized by the discharge treatment. Is produced into NO ₂ (nitrogen dioxide) and flows to the adsorption section 12 on the downstream side.

In the adsorption unit 12, the NO ₂ sent from the discharge unit 11 is efficiently adsorbed and supplemented to take out only the purified gas (Z), and the gas discharge path 2 connected to the outlet side of the adsorption unit 12. However, the switching valves 17a and 17b are closed and the switching valves 18a and 18b are opened while the discharging process of the discharging unit 11 is continued before the adsorption of the suction unit 12 is saturated.

  As a result, the purified gas (Z) discharged from the adsorption unit 12 is supplied to the reducing gas supply device 16 through the bypass line 15. The reducing gas supply device 16 takes in the purified gas (Z) that is input from the adsorption unit 12 through the bypass pipe 15 and generates the reduced gas (Y) that does not contain oxygen, and the bypass pipe 15 and the gas discharge path. 2 to the discharge unit 11.

In the discharge unit 11, NO ₂ adsorbed on the adsorption unit 12 is decomposed into NO and N ₂ by feeding the reduction gas (Y) to the adsorption unit 12 while performing discharge treatment in a reducing gas (Y) atmosphere. Then, by circulating the discharge unit 11 and the adsorption unit 12 through the reducing gas supply device 16, the adsorption unit 12 is regenerated with a completely harmless reducing atmosphere (N ₂ ) that does not contain harmful substances. That is, NO ₂ adsorbed on the adsorption unit 12 is reduced and decomposed into N ₂ . After the complete reducing atmosphere (N ₂ ) is reached, the adsorption unit 12 can be regenerated by simply stopping the original generation function of the reducing gas supply device 16 and circulating N ₂ .

FIG. 3 is a block diagram showing another embodiment of the ventilation gas purifying apparatus according to the present invention. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
In this ventilation gas purification apparatus 1, the difference from FIG. 1 is that the adsorption unit 12 is accommodated in the discharge unit 11. Since other configurations are the same as those in FIG. 1, the description will be given with reference to FIG.

4A to 4C are diagrams illustrating a detailed configuration example of the discharge unit 11 in which the suction unit 12 is housed.
In the discharge part 11 including the attracting part 12 shown in FIG. 4A, for example, three conductor electrodes 11a and four counter conductor electrodes 11b are arranged in a staggered pattern, and the conductor electrode 11a is covered with a dielectric 11c. It has been broken. And the adsorption | suction part 12 is arrange | positioned between these three conductor electrodes 11a and the four opposing conductor electrodes 11b. In addition, it may replace with the conductor electrode 11a and the structure which covers the opposing conductor electrode 11b side with the dielectric material 11c may be sufficient.

  The discharge part 11 including the adsorbing part 12 shown in FIG. 4B is configured so that one flat counter conductor electrode 11b is opposed to the three conductor electrodes 11a, 11a, 11a at a predetermined distance. This is an example of arrangement. The adsorption portion 12 is disposed between the plurality of conductor electrodes 11a, 11a, 11a and the flat opposing conductor electrode 11b.

  The discharge part 11 including the adsorption part 12 shown in FIG. 4C has a plurality of conductor electrodes 11a and a plurality of counter conductor electrodes 11b arranged in a staggered manner as in FIG. 4A, and these conductor electrodes 11a. The counter conductor electrode 11b is covered with a dielectric 11c. The arrangement of the suction unit 12 is the same as that in FIG.

By adopting such an electrode arrangement configuration, a space in which the conductor electrode 11a and the counter conductor electrode 11b are partitioned through the dielectric 11c is formed, and this space portion is a ventilation gas (X) or a reducing gas (Y). Therefore, if the adsorption part 12 is installed in this flow path portion, it is included in the ventilation gas (X) by performing a discharge treatment between the paired conductor electrode 11a and each opposing conductor electrode 11b. NO (nitrogen oxide), which is a harmful substance, is oxidized to generate NO ₂ (nitrogen dioxide), which can be adsorbed by the adsorption unit 12. The reductive decomposition action is the same as in FIG.

  FIG. 5 is an experimental example showing the relationship between the residence time and the ozone generation amount in the distance average electric field strength in the discharge section 11 in the ventilation gas purification apparatus 1 according to the present invention. The residence time means the time for the gas to pass through the discharge region.

Now, as the electrode configuration of the discharge unit 11 of the ventilation gas purification apparatus 1, the distance between the electrode 11a and the counter conductor electrode 11b via the dielectric 11c = d (cm), and the applied peak voltage = Vp (kv). The distance average electric field strength E is
E = Vp / d (kv / cm). Here, “distance” means that the applied peak voltage is divided by the interelectrode distance.

Therefore, based on such an electrode configuration, when the distance average electric field intensity E is set to 25 (kv / cm) and 50 to 60 (kv / cm), the distance average electric field intensity E for the same discharge input. It can be seen that the amount of ozone O ₃ generated is clearly increased when it is set to 50 to 60 (kv / cm) as compared with 25 (kv / cm). Here, the discharge input represents the electric power (w) required per 1 m ³ / h, which is the amount of gas per unit time.

As is clear from this experimental result, if the distance average electric field strength is at least E> 40 (kv / cm) and the gas residence time in the discharge part 11 is shortened, the amount of ozone O ₃ generated can be increased. Is possible. Further, if the distance average electric field strength is increased, not only the amount of ozone O ₃ generated can be increased, but also a compact and highly efficient discharge unit 11 can be realized.

Further, since the NOx oxidation process generates NO ₂ by the oxidation reaction between ozone (◯ ₃ ) generated by the discharge treatment in the discharge section 11 and NO, how efficiently ozone O ₃ is generated. Is an important factor. Therefore, the distance average electric field strength is more preferably 50 (kv / cm) or more.

6 and 7 are diagrams for explaining the NOx purification characteristics in the ventilation gas purification apparatus 1 according to the present invention.
FIG. 6 is a diagram showing an adsorption removal process by NO oxidation in the discharge unit 11 when the ventilation gas (X) is introduced into the ventilation gas purification device 1. The discharge treatment of the discharge unit 11, when the state of oxidizing atmosphere, NO in the ventilation gas (X) to be introduced from the gas discharge passage 2 is oxidized to form NO _2. If the discharge input is increased at this time, the oxidation amount increases to NO ₂ with the increase. Therefore, if the desired predetermined discharge input value is set, it is possible to greatly increase the NOx adsorption amount to the adsorption unit 12 and, in turn, the NOx removal amount.

FIG. 7 is a diagram showing a NOx decomposition process in the discharge unit 11 when reducing gas (Y) is introduced into the ventilation gas purification device 1. When the discharge treatment is performed in a state where the reducing gas (Y) containing no oxygen is introduced, the adsorption unit 12 becomes a reducing atmosphere, and NO ₂ adsorbed on the adsorption unit 12 is reduced and decomposed into NO and N ₂ . At this time, if the discharge input is increased, the reduction amount of N ₂ is also increased with the increase. Thereby, the adsorption unit 12 can be gradually regenerated by reductive decomposition.

  FIG. 8 is a diagram for explaining an example of switching control between the switching valves 17a, 17b and 18a, 18b when the ventilation gas purification apparatus 1 is operated.

  The ventilation gas purification apparatus 1 is newly provided with a NOx concentration sensor 21 for measuring the NOx concentration and a calculation control unit 22 in the gas discharge path 2 near the entry side of the discharge unit 11.

  The calculation control unit 22 is set with a NOx concentration regulation value before the adsorption saturation of the adsorption unit 12 based on past experience and actual measurement, and further, NOx adsorption amount judgment means and judgment results to the adsorption unit 12. Is provided with a switching control means for switching and controlling the switching valves 17a, 17b and 18a, 18b.

In this state, when the arithmetic control unit 22 opens the switching valves 17 a and 17 b and closes the switching valves 18 a and 18 b via the switching control unit, the ventilation gas (X) is introduced into the discharge unit 11. When the ventilation gas is introduced, the flow rate per unit time in the ventilation gas (X) is Q, the NOx concentration measured by the NOx concentration sensor 21 is taken in, and the integrated NOx concentration taken in from the NOx concentration sensor 21 every predetermined cycle is obtained. If X and the gas introduction time are T, the approximate amount of accumulated NOx adsorbed to the adsorption unit 12 can be predicted from the calculation formula of Q, X, and T. Therefore, the NOx adsorption amount determination means described above compares the measured integrated adsorption NOx amount with the NOx concentration prescribed value before the adsorption saturation, and when the measured accumulated adsorption NOx amount reaches the NOx concentration prescribed value. The NOx adsorption saturation to the adsorption unit 12 is determined, the switching valves 17a and 17b are closed and the switching valves 18a and 18b are opened via the switching control means, and the ventilation gas (X) is reduced from the introduction to the discharge unit 11 Switching to introduction of the gas (Y) into the discharge part 11;
As a result, the reducing gas supply device 16 takes in the purified gas (Z) on the outlet side of the adsorption unit 12 to generate, for example, N ₂ which is a reducing gas (Y) containing no oxygen, and discharge unit 11 and adsorption unit 12. Is set in a nitrogen atmosphere and discharge treatment is performed, NO ₂ adsorbed on the adsorption unit 12 is reduced and decomposed into NO and N ₂ and enters the reducing gas supply device 16. Here, when converted again to N ₂ reducing gas (Y) and circulated through the discharge unit 11 and the adsorption unit 12, NO decomposed in the adsorption unit 12 decreases, and finally an N ₂ atmosphere is obtained. The adsorption unit 12 is regenerated.

_{By the way,} at the time of introducing the reducing gas, the calculation control unit 22 takes in the NOx concentration measured by the NOx concentration sensor 21, determines whether or not the NOx concentration is equal to or lower than a preset NOx concentration prescribed value, and the NOx concentration. When the value becomes equal to or less than the NOx concentration regulation value, a switching control signal is sent, the switching valves 17a and 17b are opened, the switching valves 18a and 18b are closed, and the process proceeds to the original ventilation gas purification process.

  Therefore, by performing the switching control of the switching valves 17a, 17b and 18a, 18b for introducing the ventilation gas (X) and the reducing gas (Y) as described above, the NOx removal in the ventilation gas and the adsorption unit 12 are performed. While repeating regeneration, the ventilation gas (Z) containing harmful substances can be reliably purified and discharged without stable and complicated operation management over a long period of time.

  FIG. 9 is a block diagram showing another embodiment in which air is taken in and the reducing gas supply device 16 extracts N2 to obtain reducing gas (Y).

  A plurality of the ventilation gas purification apparatuses 1 are arranged in parallel in a bypass pipe (reducing gas channel) 15 for circulating the reducing gas. A reducing gas supply device 16 is installed at a predetermined location of the bypass conduit (reducing gas passage) 15.

  Among the plurality of ventilation gas purification devices 1,..., For example, when the adsorption unit 12 of the second ventilation gas purification device 1 from the left side in the figure reaches a predetermined specified value before NOx adsorption saturation, the corresponding ventilation gas purification is performed. After opening the switching valve 18 provided on the inlet side of the discharge unit 11 of the apparatus 1 and closing the switching valves 17a and 17b (not shown) on the input / output side of the gas exhaust path 2 of the ventilation gas (X) Then, the reducing gas supply device 16 is operated.

Unlike the embodiment described above, the reducing gas supply device 16 takes in air in the atmosphere to generate N ₂ , and has a discharge unit that is paired with the adsorption unit 12 that reaches a predetermined specified value before NOx adsorption saturation. 11, the reducing gas supply device 16 -the supply side bypass line 15 -the discharge part 11 -the adsorption part 12 -the return side bypass pipe 15 is circulated. As a result, the discharge unit 11 and the suction unit 12 is a reductive atmosphere by the N _2, is NO ₂ adsorbed in the adsorption unit 12 is reduced and decomposed into such N _2, the suction unit 12 is gradually gradual regeneration. Then, as described in FIG. 8, when the NOx concentration acquired from the NOx concentration sensor 21 becomes equal to or less than the specified value, the switching valve 18 is closed and the switching valves 17a and 17b on the input / output side of the gas discharge path 2 are closed. Open and ventilating gas (X) is introduced.

  Examples of the reducing gas supply device 16 include a PSA (Pressure Swing Adsorption) type nitrogen generator. The PSA type nitrogen generator is filled with an adsorbent having an appropriate pore size, and has a function of separating and extracting only nitrogen from gas components in the air.

FIG. 10 shows an example in which means for promoting detachment of N02 adsorbed by the adsorbing portion 12 constituting the ventilation gas purification apparatus 1 is provided.
Specifically, the ventilation gas purification apparatus 1 is provided with a heating means 23 in the adsorption unit 12 or in the reducing gas flow path 15, and during the adsorption unit regeneration operation when reducing gas is introduced, the inside of the adsorption unit 12 is used as a heating atmosphere to perform adsorption. NO ₂ which is a constituent component of NOx adsorbed on the portion 12 is efficiently promoted to promote the reductive decomposition reaction. That is, in a heated atmosphere, NOx in the adsorption unit 12 is released and released to the reducing gas (Y), whereby NOx is efficiently reduced and decomposed by the discharge treatment by the discharge unit 11, and the adsorption unit 12 is promptly moved. It is possible to reproduce.

Therefore, according to each embodiment as described above, NO is a constituent component of NOx to NO ₂ by the oxidizing atmosphere by the discharge process of the discharge unit 11 when introducing the ventilation gas. NOx can be adsorbed and removed. In addition, before the NOx adsorption saturation of the adsorption unit 12, the switching valves 17a, 17b and 18a, 18b are switched to introduce reducing gas (Y), and the adsorbed NO ₂ is discharged in a reducing atmosphere, so that the adsorption unit 12 Since the adsorption NO ₂ is reduced and decomposed into N ₂ , the adsorption unit 12 can be easily regenerated. Therefore, it is possible to reliably purify the ventilation gas containing harmful substances without performing stable and complicated operation management over a long period of time.

  In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

The block diagram which shows one Embodiment of the ventilation gas purification apparatus which concerns on this invention. The figure which shows the some example electrode structure in the discharge part shown in FIG. The block diagram which shows other embodiment of the ventilation gas purification apparatus which concerns on this invention. The figure which shows the example of a some electrode structure in the discharge part shown in FIG. The figure explaining the relationship between the gas residence time in the distance average electric field strength in a discharge part, and ozone generation amount. It shows the oxidation characteristic to NO ₂ from NO. Diagram illustrating the reductive decomposition characteristic of the NO ₂ to N _2. The figure explaining the switching control of each switching valve provided in the ventilation gas purification apparatus, and the ventilation gas purification method which concerns on this invention. The block diagram which shows other embodiment of the ventilation gas purification apparatus which concerns on this invention. The block diagram which shows other another embodiment of the ventilation gas purification apparatus which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ventilation gas purification apparatus, 2 ... Gas discharge path, 11 ... Discharge part, 11a ... Conductor electrode, 11b ... Opposite conductor electrode, 11c ... Dielectric, 12 ... Adsorption part, 14 ... Power supply for discharge, 15 ... Bypass line (Reducing gas flow path), 16 ... reducing gas supply device, 17a, 17b, 18a, 18b, 18 ... switching valve, 21 ... NOx concentration sensor, 22 ... arithmetic control unit, 23 ... heating means.

Claims (6)

Provided in the gas discharge path of the ventilation gas of oxygen coexist, discharge treatment by the a component of the NOx included in the ventilation gas (nitrogen oxides) NO (nitrogen monoxide) is oxidized to NO ₂ (2 nitric oxide ) Generating a discharge part;
An adsorption unit that adsorbs and removes NO ₂ generated by the discharge unit and discharges purified purified gas;
A reducing gas supply device that generates a reducing gas that does not contain oxygen, provided on a reducing gas flow path provided across the discharge unit and the adsorption unit;
The ventilation gas and the reducing gas are alternately introduced into the discharge unit by selecting the gas discharge path and the reducing gas channel, and are adsorbed on the adsorption unit by a discharge process by the discharge unit when the reducing gas is introduced. A ventilation gas comprising switching control means for recirculating the NO ₂ , which is a harmful substance, into a harmless gas and circulating it through the reducing gas supply device to regenerate the adsorption unit Purification equipment. In the ventilation gas purification apparatus of Claim 1,
The electrode configuration of the discharge part is composed of a first conductor electrode, a second conductor electrode facing the first conductor electrode, and a dielectric covering at least one of the conductor electrodes,
When the distance between the first conductor electrode and the second conductor electrode is d (cm) and the absolute value of the applied peak voltage between the first and second conductor electrodes is Vp (kv),
A ventilation gas purifying apparatus characterized in that, based on the distance average electric field strength E = Vp / d, the distance average electric field strength E is set to satisfy E> 40 (kv / d). In the ventilation gas purification apparatus of Claim 1,
A ventilation gas purifying device, wherein the reducing gas produced by the reducing gas supply device and introduced into the discharge section is N ₂ (nitrogen gas). In the ventilation gas purification apparatus as described in any one of Claims 1 thru | or 3,
A NOx concentration sensor is provided in the gas discharge path connected to the entry side of the discharge unit,
The switching control unit integrates the NOx amount measured by the NOx concentration sensor when the ventilation gas is introduced into the discharge unit, and the accumulated NOx amount reaches a predetermined amount before adsorption saturation of the adsorption unit. The ventilation gas purification apparatus characterized by sometimes selecting the reducing gas flow path and introducing the reducing gas from the reducing gas supply apparatus to the discharge section. In the ventilation gas purification apparatus as described in any one of Claims 1 thru | or 4,
A ventilation gas purifying apparatus, characterized in that a heating means is provided in the adsorbing part or the reducing gas flow path for separating harmful substances adsorbed on the adsorbing part. A discharge step of performing discharge treatment in the discharge section on the ventilation gas coexisting with oxygen, and oxidizing NO that is a constituent of NOx in the ventilation gas to generate NO2;
An adsorption step of adsorbing and removing NO2 generated by this discharge step at the adsorption unit and discharging the purified gas after purification,
An amount of NOx is integrated when the ventilation gas is introduced into the discharge unit, and an adsorption amount determination step of whether or not the integrated NOx amount has reached a predetermined amount before the adsorption saturation of the adsorption unit;
When the accumulated NOx amount reaches a specified amount before the adsorption saturation of the adsorption unit, it is switched to a reducing gas supply system, and a reducing gas not containing oxygen is introduced from the reducing gas supply system into the discharge unit during the discharge process, And a regeneration process step of regenerating the adsorbing part while reducing and decomposing the harmful substances adsorbed on the adsorbing part.

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