JP2006122866A - Treatment method and treatment apparatus of gaseous halogen compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method and a treatment apparatus for a gaseous halogen compound which are capable of detoxicating a gaseous halogen compound such as methyl bromide, lessening the load on global environments, and decreasing the treatment cost, and by which a treatment facility can be made sufficiently compact. <P>SOLUTION: The treatment method involves steps of decomposing a halogen compound by bringing a gas current containing the halogen compound into contact with electric discharge plasma and forming a salt of the halogen and a metal for halogen fixation by bringing a gas current containing the decomposition product produced in the decomposition step into contact with a chemical solution containing the metal ion. The treatment apparatus 1 comprises an electric discharge plasma reactor 2 for causing reaction of the gas current containing the gaseous halogen compound with electric discharge plasma generated in the reactor and a scrubber 3 for bringing the gas current after the reaction in the electric discharge plasma reactor into contact with the chemical solution containing the metal ion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a treatment method and a treatment apparatus for decomposing and detoxifying gaseous halogen compounds such as methyl bromide gas used for fumigation treatment for insecticidal purposes carried out during quarantine, for example.

  For example, imported foods are fumigated for pesticidal purposes during quarantine. Methyl bromide gas is often used as an insecticide for this fumigation treatment. For example, as shown in FIG. 9, after placing an object to be fumigated (fumigation target) (101) in a fumigation warehouse (100), methyl bromide (103) is activated by operating a blower (102) for internal circulation. Is circulated in the fumigation warehouse (100). Methyl bromide has a vaporization point of about 3 to 4 ° C. and is vaporized at room temperature. Therefore, it becomes a gas and circulates in the fumigation warehouse (100) and is placed in the fumigation warehouse (100). Stick to (101) to kill insects. After performing the fumigation process for a predetermined time, the exhaust blower (104) discharges the gas in the fumigation warehouse (100), and the intake air blower (105) sends new air into the warehouse (100). While diluting, the methyl bromide gas (103) in the fumigation warehouse (100) is released into the atmosphere as an exhaust gas.

  The concentration of methyl bromide used in insecticidal fumigation during quarantine is generally 3000-12000 ppm, and a large amount of methyl bromide is used in one fumigation process, but at present most cases The methyl bromide after fumigation is released to the atmosphere as it is without any treatment. However, methyl bromide has an ozone depletion coefficient of 0.6 (ODP) and is a substance that promotes ozone layer depletion and has ecotoxicity, so the concentration of methyl bromide released into the atmosphere is suppressed. There is a need to. In recent years, there is a strong demand to suppress the release of methyl bromide to the atmosphere as the demand for protecting the global environment increases.

  Under such circumstances, an adsorption method using activated carbon has been proposed as a method for treating methyl bromide (see Cited Document 1). For example, as shown in FIG. 10, activated carbon (111) is arranged in an activated carbon adsorption tower (110), and methyl bromide gas (112) after fumigation sent from a fumigation warehouse is transferred to the activated carbon adsorption tower (110). ) And adsorbed methyl bromide with the activated carbon (111) for separation, and then the gas (113) after the adsorption treatment is released to the atmosphere.

Further, as a method for treating methyl bromide, a method for subjecting methyl bromide gas to combustion decomposition has also been proposed (see Patent Document 1).
JP-A-11-197455 (Claims 1 and 5)

  However, in the activated carbon adsorption method, the amount of methyl bromide adsorbed on the activated carbon has a saturation amount, so that in order to treat a large amount of methyl bromide used in fumigation treatment, the adsorbent activated carbon is inevitably. There has been a problem that the amount of filling has to be increased and the equipment volume becomes enormous and the equipment becomes larger. Further, in the activated carbon adsorption method, methyl bromide is adsorbed and trapped on activated carbon, and therefore, methyl bromide cannot be fundamentally detoxified. Furthermore, since it is necessary to dispose of the activated carbon that has adsorbed methyl bromide, there is also a problem of placing a burden on the global environment.

  Further, the combustion decomposition treatment method has a problem that bromine oxide having a toxicity higher than that of methyl bromide is generated by the combustion treatment of methyl bromide. That is, a secondary treatment for detoxifying the generated bromine oxide is required. Moreover, in order to burn methyl bromide gas, it is necessary to set the heating temperature to 500 ° C. or higher, and a large amount of heat energy is required for the treatment, so that there is a problem that a great cost is required. Furthermore, the equipment of the combustion decomposition treatment apparatus has to be large, and there is a problem that it is difficult to reduce the size.

  The present invention has been made in view of such a technical background, and is capable of detoxifying a gaseous halogen compound such as methyl bromide, thereby reducing the burden on the global environment and protecting the global environment. To provide a processing method and a processing apparatus for gaseous halogen compounds that can sufficiently contribute, can reduce processing costs without requiring a large amount of heat energy, and can sufficiently reduce the size of processing equipment. Objective.

  In order to achieve the above object, the present invention provides the following means.

[1] a decomposition treatment step of decomposing the halogen compound by bringing a gas stream containing a gaseous halogen compound into contact with discharge plasma;
And a halogen fixing step of forming a salt of the halogen and the metal by bringing a gas stream containing the decomposition product generated by the decomposition treatment into contact with a chemical solution containing metal ions. Halogen compound treatment method.

[2] a decomposition treatment step of decomposing the methyl bromide by bringing a gas stream containing methyl bromide gas into contact with the discharge plasma;
A halogen fixing step of forming a metal bromide salt by bringing a gas stream containing hydrogen bromide generated by the decomposition treatment into contact with a chemical solution containing metal ions. Processing method.

[3] A flow feeding step of feeding a gas flow containing methyl bromide gas after being used for the fumigation treatment from the fumigation warehouse into the discharge plasma reactor;
A decomposition treatment step of decomposing the methyl bromide by bringing a gas flow containing the methyl bromide gas into contact with the discharge plasma in the discharge plasma reactor;
A halogen fixing step of forming a metal bromide salt by bringing a gas stream containing hydrogen bromide generated by the decomposition treatment into contact with a chemical solution containing metal ions;
A return flow step for returning the gas flow after the halogen fixing step into the fumigation warehouse,
A method for treating a gaseous halogen compound, wherein the circulation treatment comprising the flow feeding step, the decomposition treatment step, the halogen fixing step, and the return flow step is performed one or more times.

  [4] The method for treating a gaseous halogen compound according to any one of the above items 1 to 3, wherein a chemical solution containing sodium ions is used as the chemical solution containing metal ions.

  [5] The method for treating a gaseous halogen compound according to any one of items 1 to 3, wherein a sodium hydroxide aqueous solution is used as the chemical solution containing the metal ion.

  [6] A non-equilibrium generated by a pulse corona reactor that generates a pulse corona between both electrodes by applying a pulse voltage between the discharge electrode and the counter electrode that are arranged apart from each other as the discharge plasma. 6. The method for treating a gaseous halogen compound according to any one of items 1 to 5, wherein plasma is used.

[7] A discharge plasma reactor for reacting a gas stream containing a gaseous halogen compound with the discharge plasma generated in the vessel;
An apparatus for treating a gaseous halogen compound, comprising: a scrubber for bringing a gas flow after reacting in the discharge plasma reactor into contact with a chemical solution containing metal ions.

[8] A pulse corona reactor for reacting a gas stream containing a gaseous halogen compound with non-equilibrium plasma generated in the chamber;
An apparatus for treating a gaseous halogen compound, comprising: a scrubber for bringing a gas flow after reacting in the pulse corona reactor into contact with a chemical solution containing metal ions.

[9] Fumigation warehouse,
A pulse corona reactor for reacting a gas stream containing a gaseous halogen compound sent from the fumigation warehouse with non-equilibrium plasma generated in the vessel;
A scrubber for contacting the gas flow after reacting in the pulse corona reactor with a chemical containing metal ions;
In addition to introducing a gas flow sent from the scrubber, a switching damper capable of switching between a route for returning the gas flow to the fumigation warehouse and a route for releasing the gas flow to the atmosphere as it is. Equipment for treating gaseous halogen compounds.

  [10] In the pulse corona reactor, the distance between the discharge electrode and the counter electrode is set to 100 mm or less, the distance average electric field strength is set to rise at 10 V / cm / ns or more, and the maximum value is 5 kV / cm. 10. The apparatus for treating a gaseous halogen compound according to 8 or 9 above, which is set to apply the pulse high voltage as described above at least 100 times per second.

  [11] In the pulse corona reactor, the counter electrode is formed in a spiral coil shape, while the discharge electrode is formed by a linear electrode twisted with a square wire, and the linear discharge electrode is formed in the spiral coil. 11. The apparatus for processing a gaseous halogen compound according to any one of the above items 8 to 10, which is inserted and disposed in a space in a spiral of the counter electrode having a shape.

  [12] The apparatus for treating a gaseous halogen compound as described in any one of [8] to [11], wherein a dielectric is coated on the surface of the counter electrode of the pulse corona reactor.

  [13] The apparatus for processing a gaseous halogen compound as described in [12] above, wherein one or more dielectrics selected from the group consisting of ceramic, glass and resin are used as the dielectric.

  [14] The apparatus for treating a gaseous halogen compound as described in any one of [7] to [13], wherein a chemical solution containing sodium ions is used as the chemical solution containing metal ions.

  [15] The apparatus for treating a gaseous halogen compound as described in any one of [7] to [13], wherein a sodium hydroxide aqueous solution is used as the chemical solution containing the metal ions.

  In the invention of [1], since the gas stream containing the gaseous halogen compound is brought into contact with the discharge plasma, the halogen compound can be decomposed by the action of the discharge plasma, and further the gas stream containing the decomposition product is converted into a metal stream. Since it is brought into contact with the chemical solution containing ions, this makes it possible to form a metal halide salt and to detoxify the gaseous halogen compound. Since the gaseous halogen compound can be detoxified in this way, the release of halogen compounds that promote ozone layer destruction to the atmosphere can be sufficiently suppressed, and the release of toxic substances to the atmosphere can also be suppressed. It can reduce the burden on the global environment and can contribute to the protection of the global environment. Moreover, since a great amount of heat energy is not required for processing, the processing cost can be reduced. In addition, in this treatment method, waste such as activated carbon adsorbed with gas is not generated, so that the load on the global environment can be extremely small also in this respect. Furthermore, in this processing method, the processing equipment can be sufficiently downsized.

  [2] In the invention of [3], since the gas stream containing methyl bromide gas is brought into contact with the discharge plasma, the bromide can be decomposed by the action of the discharge plasma, and further, the bromide which is a decomposition product is bromide. Since the gas stream containing hydrogen is brought into contact with a chemical solution containing metal ions, a metal bromide salt can be formed thereby, and thus methyl bromide gas can be rendered harmless. Since methyl bromide gas can be detoxified in this way, the release of methyl bromide gas that promotes ozone layer destruction to the atmosphere can be sufficiently suppressed, and the release of toxic substances to the atmosphere can also be suppressed. It can reduce the burden on the global environment and can contribute to the protection of the global environment. Moreover, since a great amount of heat energy is not required for processing, the processing cost can be reduced. In addition, in this treatment method, waste such as activated carbon adsorbed with gas is not generated, so that the load on the global environment can be extremely small also in this respect. Furthermore, in this processing method, the processing equipment can be sufficiently downsized.

  Further, in the invention of [3], the methyl bromide gas detoxification treatment is carried out by performing the circulation treatment comprising the flow feeding step, the decomposition treatment step, the halogen fixing step and the return flow step one or more times. Since the detoxification process (decomposition process of methyl bromide gas) is advanced, there is an advantage that it can be handled with a small facility and the detoxification process of methyl bromide gas can be performed to a sufficient extent.

  In the invention of [4], since the chemical solution containing sodium ions is used as the chemical solution containing metal ions, there is an advantage that a metal bromide salt (sodium bromide salt) can be formed efficiently in the halogen fixing step.

  In the invention of [5], since an aqueous sodium hydroxide solution is used as a chemical solution containing metal ions, there is an advantage that a metal bromide salt (sodium bromide salt) can be formed more efficiently in the halogen fixing step.

  In the invention of [6], the discharge plasma is generated by a pulse corona reactor that generates a pulse corona between both electrodes by applying a pulse voltage between a discharge electrode and a counter electrode that are spaced apart from each other. In addition, since the non-equilibrium plasma is used, the decomposition process of the gaseous halogen compound can be carried out very efficiently, and the detoxification process can be performed in a short time.

  The invention (processing apparatus) of [7] includes a discharge plasma reactor for reacting a gas flow containing a gaseous halogen compound with a discharge plasma generated in the vessel, wherein the gaseous halogen compound is contained in the discharge plasma reactor. The gas stream containing gas can be contacted with the discharge plasma to decompose the halogen compound, and the gas stream containing the decomposition product is brought into contact with the chemical solution containing metal ions in the scrubber. Thus, the gaseous halogen compound can be detoxified. Since the gaseous halogen compound can be detoxified in this way, the release of halogen compounds that promote ozone layer destruction to the atmosphere can be sufficiently suppressed, and the release of toxic substances to the atmosphere can also be suppressed. It can reduce the burden on the global environment and can contribute to the protection of the global environment. Moreover, since a great amount of heat energy is not required for processing, the processing cost can be reduced. In addition, since the present processing apparatus does not generate waste such as activated carbon that has adsorbed gas, the load on the global environment can be extremely small. Furthermore, in this processing apparatus, the processing equipment can be sufficiently downsized.

  [8] The invention (processing apparatus) of [9] includes a pulse corona reactor for reacting a gas stream containing a gaseous halogen compound with non-equilibrium plasma generated in the reactor, and in the pulse corona reactor, A gas stream containing methyl bromide gas can be contacted with discharge plasma to decompose methyl bromide, and a gas stream containing hydrogen bromide, which is a decomposition product, in a scrubber is brought into contact with a chemical solution containing metal ions. Thus, a metal bromide salt can be formed thereby, and thus methyl bromide gas can be rendered harmless. Since methyl bromide gas can be detoxified in this way, the release of methyl bromide gas that promotes ozone layer destruction to the atmosphere can be sufficiently suppressed, and the release of toxic substances to the atmosphere can also be suppressed. It can reduce the burden on the global environment and can contribute to the protection of the global environment. Moreover, since a great amount of heat energy is not required for processing, the processing cost can be reduced. In addition, since the present processing apparatus does not generate waste such as activated carbon that has adsorbed gas, the load on the global environment can be extremely small. Furthermore, in this processing apparatus, the processing equipment can be sufficiently downsized.

  Furthermore, in the invention of [9], a gas circulation path including a fumigation warehouse, a pulse corona reactor, a scrubber, and a switching damper is configured, and a circulation process is performed by passing a gas flow through the gas circulation path. There is an advantage that it can be handled with a small facility and that the detoxification treatment of methyl bromide gas can be performed to a sufficient extent. Further, since a switching damper is provided, when the concentration of methyl bromide gas in the gas flow passing through the gas circulation path is lower than a predetermined concentration, the switching damper is set to switch from the switching damper. The treated gas can be released to the atmosphere. When the concentration of methyl bromide gas in the gas flow passing through the gas circulation path is higher than a predetermined concentration, the gas flow sent to the switching damper by setting the switching damper is changed to a fumigation warehouse. It can be returned to the inside for recirculation.

  In the invention of [10], the pulse corona reactor is set such that the distance between the discharge electrode and the counter electrode is set to 100 mm or less, the distance average electric field strength is set to rise at 10 V / cm / ns or more, and the maximum value is Since it is set to apply a pulse high voltage of 5 kV / cm or more 100 times or more per second, the conversion rate from gaseous halogen compounds to decomposition products (conversion rate from methyl bromide to hydrogen bromide) is There is an advantage of becoming very large. Thereby, the processing efficiency of the processing apparatus is remarkably improved.

  In the invention of [11], in the pulse corona reactor, the counter electrode is formed in a spiral coil shape, while the discharge electrode is formed by a linear electrode twisted with a square wire, and the linear discharge electrode is a spiral coil Therefore, the amount of non-equilibrium plasma generated is greatly increased, and the decomposition efficiency can be further improved.

  In the invention of [12], since the dielectric is coated on the surface of the counter electrode of the pulse corona reactor, the pulse corona that develops from the discharge electrode can be prevented from bridging with the counter electrode.

  In the invention of [13], one or more dielectrics selected from the group consisting of ceramic, glass and resin are used as the dielectric, so that the pulse corona that develops from the discharge electrode is connected to the counter electrode and the bridge. Entanglement can be reliably prevented.

  In the invention of [14], since a chemical solution containing sodium ions is used as the chemical solution containing metal ions, a metal bromide salt (sodium bromide salt) can be efficiently formed in a scrubber.

  In the invention of [15], an aqueous sodium hydroxide solution is used as a chemical solution containing metal ions, so that a metal bromide salt (sodium bromide salt) can be formed more efficiently in a scrubber.

  FIG. 1 shows an embodiment of a gaseous halogen compound treatment apparatus (1) according to the present invention. In the present embodiment, a case where the gaseous halogen compound is methyl bromide will be described as an example. In FIG. 1, (2) is a discharge plasma reactor, (3) is a scrubber, and (6) is a fumigation warehouse.

  In the fumigation warehouse (6), an object to be fumigated (an object to be fumigated) (41) is arranged, and an internal circulation fan (40) is further arranged. When performing the fumigation treatment, methyl bromide (42) is left in the fumigation warehouse (1). The internal circulation blower (40) is a facility for circulating vaporized methyl bromide in the fumigation warehouse (1).

  A damper (21) is attached and fixed to an opening provided at the bottom of the side wall of the fumigation warehouse (6), and a first gas induction pipe (25) is connected to the damper (21). The other end (right end of the drawing) of the first gas induction tube (25) is connected to the side wall of the discharge plasma reactor (2). The damper (21) is closed during the fumigation process so that the fumigation warehouse (6) is closed. A damper (22) described later is similarly closed during the fumigation process.

  In this embodiment, a pulse corona reactor is used as the discharge plasma reactor (2). The pulse corona reactor (2) includes a pulse power source (11) outside, and a discharge electrode (12) and a counter electrode (13) in the reactor (2). In this embodiment, a spiral configuration as shown in FIG. 2 is adopted. That is, the counter electrode (13) is formed in a spiral coil shape, and the discharge electrode (12) is formed by a linear electrode twisted (twisted) with a rectangular cross section, and the linear discharge electrode (12 ) Is inserted and arranged in the spiral space of the spiral coil-shaped counter electrode (13). A dielectric (not shown) is coated on the surface of the counter electrode (13). One end of the discharge electrode (12) is connected to an external pulse power source (11), and one end of the counter electrode (13) is also connected to an external pulse power source (11). By applying a pulse voltage between the electrode (12) and the counter electrode (13), non-equilibrium plasma (low temperature plasma) of a pulse corona can be generated between the electrodes (12) and (13).

  In the pulse corona reactor (2), a gas flow containing methyl bromide sent from the fumigation warehouse (6) through the damper (21) and the first gas induction pipe (25) is reacted. It is brought into contact with the non-equilibrium plasma generated in the vessel (2) to cause a decomposition reaction. That is, as shown in FIG. 2, a gas flow containing methyl bromide is sent into the spiral space of the spiral coil-shaped counter electrode (13) and brought into contact with non-equilibrium plasma to cause a decomposition reaction. By this reaction, the methyl bromide is decomposed and converted to hydrogen bromide. In FIG. 2, (14) indicates a gas flow before decomposition, and (15) indicates a gas flow after decomposition.

  Side walls of the pulse corona reactor (2) and the scrubber (3) are connected to each other via a second gas induction pipe (26). As shown in FIG. 3, the scrubber (3) includes a processing tower (30), spray nozzle portions (31) (31) provided in the processing tower (30), and the inside of the processing tower (30). And a gas-liquid contact layer portion (32) provided on the surface. The second gas induction pipe (26) is connected to the lower position of the side wall of the processing tower (30), and the third gas induction pipe (27) is connected to the upper position of the side wall of the processing tower (30). Communication connection is established. The gas-liquid contact layer portion (32) is disposed at a position higher than the mounting position of the second gas induction pipe (26) in the processing tower (30). This gas-liquid contact layer part (32) consists of a plurality of perforated plates stacked one above the other, and the perforated plates are arranged apart from each other. Spray nozzle portions (31) (31) are provided at positions between the gas-liquid contact layer portion (32) and the third gas guide pipe (27) mounting position in the processing tower (30). That is, the spray nozzle portions (31) (31) are fixedly mounted at positions lower than the mounting position of the third gas induction pipe (27) on the side wall of the processing tower (30).

  A large number of nozzle holes are formed in the spray nozzle part (31), and a chemical solution (34) containing metal ions is sprayed into the processing tower (30) from these nozzle holes. Thus, the gas flow (gas flow containing hydrogen bromide as a decomposition product) sent from the second gas induction pipe (26) passes through the processing tower (30) of the scrubber (3). Then, it is sent to the next switching damper (5) through the upper third gas induction pipe (27), and this gas flow is passed through the processing tower (30) of the scrubber (3). First, in the gas-liquid contact layer portion (32) during the passage of the gas, it comes into contact with the metal ion-containing chemical solution (34) that has been sprayed and dropped from the spray nozzle portion (31) on the upper side, and is further in contact with the gas-liquid In contact with the metal ion-containing chemical liquid (34) sprayed from the spray nozzle part (31) in the space above the contact layer part (32). A metal bromide salt is formed by contact with such a metal ion-containing chemical solution (34), and this metal bromide salt is retained at the bottom of the processing tower (30) of the scrubber (3) (halogen). Fixed).

  A third gas induction pipe (27) is attached and fixed to an opening provided at an upper position of the side wall of the scrubber (3), and the other end of the third gas induction pipe (27) is connected to the suction fan (4). Has been. The suction fan (4) is connected in communication with the switching damper (5) via the fourth gas guide pipe (28). Further, the switching damper (5) is connected in communication with the other end of the fifth gas guide pipe (29) connected to an opening provided at an upper position of the side wall of the fumigation warehouse (6). When the suction fan (4) is operated, the gas in the fumigation warehouse (6) is sucked to the fan (4) side, and the damper (21), the first gas induction pipe (25), the pulse The corona reactor (2), the second gas induction pipe (26), the scrubber (3), and the third gas induction pipe (27) are sequentially passed through the suction fan (4) and further to the fourth gas induction pipe (28). To the switching damper (5). When the switching damper (5) is switched to be connected to the fifth gas induction pipe (29), the gas passes through the fifth gas induction pipe (29) and the damper (22) in this order. Pass through and return to the fumigation warehouse (1) to join. Further, when the switching damper (5) is switched to open to the outside, the gas is released to the outside atmosphere.

  Then, the dampers (21) and (22) are closed, and the fumigation process is performed for a predetermined time with methyl bromide (42) in the fumigation warehouse (6). Thereafter, the dampers (21) and (22) are opened to communicate with each other, the suction fan (4) is operated, and the discharge plasma reactor (pulse corona reactor) (2) is put into operation.

  By the operation of the suction fan (4), the gas in the fumigation warehouse (6) (the gas containing methyl bromide gas) passes through the damper (21) and the first gas induction pipe (25) to the pulse corona reactor ( 2) is introduced. In the pulse corona reactor (2), a pulse voltage is applied between the discharge electrode (12) and the counter electrode (13) by using a pulse power source (11), so that both electrodes (12) and (13) are connected. In this case, the non-equilibrium plasma of the pulse corona is generated, and the methyl bromide gas in the gas introduced into the reactor (2) comes into contact with the non-equilibrium plasma and is decomposed by the action of the non-equilibrium plasma, so that hydrogen bromide Converted to The gas flow (gas flow containing hydrogen bromide) subjected to such decomposition treatment passes through the second gas induction pipe (26) by the suction action of the suction fan (4) and enters the scrubber (3). be introduced.

  In the scrubber (3), the introduced gas stream (a gas stream containing hydrogen bromide which is a decomposition product) is firstly sprayed at the upper part of the spray nozzle part (31) in the gas-liquid contact layer part (32). The metal ions sprayed from the nozzle and contacted with the metal ion-containing chemical liquid (34) that has fallen and adhered, and further sprayed from the spray nozzle section (31) in the space above the gas-liquid contact layer section (32). Contact with the contained chemical (34). A metal bromide salt is formed by contact with such a metal ion-containing chemical solution (34), and this metal bromide salt is retained at the bottom of the processing tower (30) of the scrubber (3) (halogen). Fixed). That is, in FIG. 3, (33) is a post-reaction solution (for example, metal bromide salt + water). The solution after the reaction (for example, sodium bromide aqueous solution) is discharged and recovered. The recovered sodium bromide can be reused, for example, for photographic materials.

  The gas flow having undergone the fixing treatment passes through the third gas induction pipe (27) by the suction action of the suction fan (4), passes through the suction fan (4), and further passes through the fourth gas induction pipe (28). Reach the switching damper (5). The switching damper (5) is connected to the fifth gas induction pipe (29) when the methyl bromide gas concentration in the gas passing through the fourth gas induction pipe (28) is higher than a predetermined concentration. Therefore, the gas passes through the fifth gas induction pipe (29) and the damper (22) in this order and is returned to the fumigation warehouse (1) to join (gas is circulated). .

  Therefore, the circulation treatment operation using the discharge plasma reactor (2) and the scrubber (3) is repeated one or more times. When the methyl bromide gas concentration in the gas that has passed through the fourth gas induction pipe (28) is lower than a predetermined concentration after one circulation operation or a plurality of repeated circulation treatment operations, a switching damper ( In 5), since the switching is performed so as to open to the outside, in this case, the gas is released to the outside atmosphere. The gas thus released into the atmosphere is a gas that hardly contains methyl bromide gas or hydrogen bromide gas. In this way, the release of methyl bromide gas, which promotes ozone layer destruction, to the atmosphere can be sufficiently suppressed, and the release of toxic substances to the atmosphere can also be suppressed, thereby reducing the burden on the global environment. It can be reduced and can fully contribute to the protection of the global environment.

  Further, in the present processing method using the processing apparatus (1), a large amount of heat energy is not required for the processing, so that the processing cost can be reduced. In addition, in this treatment method, waste such as activated carbon adsorbed with gas is not generated, so that the load on the global environment can be extremely small also in this respect. Further, in the present processing apparatus (1), neither the discharge plasma reactor (2) nor the scrubber (3) is a large facility, and can be sufficiently miniaturized to constitute a small processing apparatus (1). There are also advantages.

  In the above embodiment, the scrubber (3) employs a structure having a spray nozzle part (31) and a gas-liquid contact layer part (32) in the processing tower (30). In particular, it is not limited to the thing of such a structure. For example, you may employ | adopt the structure shown to FIG. A scrubber (3) shown in FIG. 7 (a) is a bubbling scrubber, and a gas flow (a gas containing hydrogen bromide as a decomposition product) in a metal ion-containing chemical liquid (34) in the processing tower (30). The gas stream and the chemical solution (34) are brought into contact with each other to form a metal bromide salt. Moreover, the scrubber (3) shown in FIG. 7 (b) is a gas-liquid contact layer type scrubber, which falls from above in the gas-liquid contact layer portion (32) and stays attached and retains the metal ion-containing chemical solution (34). ) And a gas stream (a gas stream containing hydrogen bromide as a decomposition product) are contacted to form a metal bromide salt. The scrubber (3) shown in FIG. 7 (c) is a spray-type scrubber, and in the internal space of the processing tower (30), the metal ion-containing chemical liquid (34) sprayed from the spray nozzle part (31) and The gas stream (a gas stream containing hydrogen bromide as a decomposition product) is contacted to form a metal bromide salt. Among these, from the viewpoint of sufficiently increasing the contact efficiency between the metal ion-containing chemical solution and the gas flow, the configuration of the present embodiment (with the spray nozzle portion (31) and the gas-liquid contact layer portion (32) in the processing tower). It is preferable to adopt the configuration described above.

  Although it does not specifically limit as said chemical | medical solution (34) containing the metal ion, For example, the chemical | medical solution etc. which contained sodium ion are mentioned. Examples of the chemical solution containing sodium ions include a sodium hydroxide aqueous solution and a calcium hydroxide aqueous solution. Among these, it is preferable to use a sodium hydroxide aqueous solution from the viewpoint of efficiently forming a sodium bromide salt.

  Moreover, in the said embodiment, although the helical structure as shown in FIG. 2 is employ | adopted as an electrode structure in a pulse corona reactor (2), it is not specifically limited to the thing of such a structure. For example, you may employ | adopt the electrode structure shown to FIGS. In FIG. 4, flat discharge electrodes (12) (12) (12) (12) and flat counter electrodes (13) (13) (13) (13) are alternately arranged in parallel with a predetermined interval. Adopted an open arrangement. Further, in FIG. 5, linear discharge electrodes (12), (12), and (12) are inserted and arranged in a facing space between a pair of spaced flat electrodes (13) and (13). The configuration is adopted. Moreover, in FIG. 6, the structure by which the linear discharge electrode (12) was penetrated by the internal space of a cylindrical counter electrode (13) is employ | adopted. 5 and 6, (14) shows a gas flow before decomposition, and (15) shows a gas flow after decomposition.

  In the pulse corona reactor (2), the distance between the discharge electrode (12) and the counter electrode (13) is preferably set to 100 mm or less. If it exceeds 100 mm, the energy density per unit volume in the reaction space tends to decrease and the decomposition rate tends to decrease, such being undesirable.

  In the pulse corona reactor (2), the distance average electric field strength is preferably set so as to rise at 10 V / cm / ns or more. The “distance average electric field strength” is a value obtained by dividing the voltage of the applied pulse high voltage by the distance between the discharge electrode and the counter electrode.

  Further, the pulse corona reactor (2) is preferably set to apply a pulse high voltage having a maximum value of 5 kV / cm or more 100 times or more per second. Less than 100 times per second is not preferable because the energy density per unit volume in the reaction space tends to decrease and the decomposition rate tends to decrease.

  A suitable voltage waveform (23) and current waveform (24) in the pulse corona reactor (2) are shown in FIG. It is desirable to apply a high voltage pulse having such a steep rising waveform of several hundred nanoseconds. In this case, methyl bromide can be converted to hydrogen bromide at a high conversion rate by the generated non-equilibrium plasma (low temperature plasma), and it is sufficiently possible to achieve a conversion rate of 90% or more.

  In the above embodiment, the surface of the counter electrode (13) is coated with a dielectric, but a configuration in which such a dielectric is not coated may be employed. However, from the viewpoint of effectively preventing the pulse corona extending from the discharge electrode (12) from bridging with the counter electrode (13), the surface of the counter electrode (13) is covered with a dielectric. It is preferable to adopt. Although it does not specifically limit as said dielectric material, It is preferable to use the 1 type, or 2 or more types of dielectric material chosen from the group which consists of ceramic, glass, and resin.

  Further, in the above embodiment, the treatment of fumigation methyl bromide gas has been described. However, the treatment method and treatment apparatus of the present invention are not particularly limited to such treatment of methyl bromide gas, for example, other equipment. It can also be applied to the treatment of methyl bromide gas used in applications. Furthermore, the treatment method and treatment apparatus of the present invention are not limited to the treatment of methyl bromide gas, but can be applied to the treatment of gases containing other gaseous halogen compounds. Examples of other applicable gaseous halogen compounds include Freon gas (CFC-12), trichlorotrifluoroethane (CFC-113), and the like.

  Moreover, in the said embodiment, although it processes using the discharge plasma (non-equilibrium plasma) by a pulse corona reactor, it is not specifically limited only to the discharge plasma by such a pulse corona reactor, For example, Processing may be performed using discharge plasma by arc discharge or discharge plasma by glow discharge, and the present invention also includes processing by this kind of discharge plasma. However, it is desirable to perform the decomposition treatment using non-equilibrium plasma by a pulse corona reactor in that a higher decomposition rate can be obtained.

  Next, specific examples of the present invention will be described.

<Example 1>
The treatment apparatus (1) having the configuration shown in FIG. 1 was used to detoxify methyl bromide gas after being used for fumigation in the fumigation warehouse (6). That is, after the fumigation treatment, the dampers (21) and (22) were opened and brought into communication, the suction fan (4) was operated, and the discharge plasma reactor (pulse corona reactor) (2) was put into operation.

  Due to the operation of the suction fan (4), the gas flow rate in the fourth gas induction pipe (28) was 5600 L / min. The methyl bromide gas concentration in the fumigation warehouse (6) immediately after the fumigation treatment was 10,000 ppm. The frequency of the pulse corona reactor (2) was set to 1000 Hz and the voltage was set to 80 kV. Further, the pulse corona reactor (2) has an electrode structure of a spiral type as shown in FIG. 2, the distance between the discharge electrode and the counter electrode is set to 90 mm, and the distance average electric field strength is 1000 V / cm / ns or more. The pulse high voltage having a maximum value of 5 kV / cm or more is set to be applied 1000 times per second. In the scrubber (3), a 1.25 mol / L (5% aqueous solution) sodium hydroxide aqueous solution was used as a chemical solution.

  Thus, after the operation of the processing apparatus (1) is started, the methyl bromide gas concentration in the fourth gas induction pipe (28) for each elapsed time is shown in Table 1. It can be seen that the methyl bromide gas concentration decreases with time.

  After confirming that the methyl bromide gas concentration was 1 ppm or less after 8 hours, the switching damper (5) was switched to open to the outside to release the gas flow to the outside atmosphere.

<Example 2>
Harmless methyl bromide gas after being used for fumigation in the fumigation warehouse (6) in the same manner as in Example 1 except that the methyl bromide gas concentration in the fumigation warehouse (6) immediately after the fumigation treatment was 5000 ppm. The treatment was performed. Table 1 shows the methyl bromide gas concentration in the fourth gas induction pipe (28) for each elapsed time after the start of the operation of the processing apparatus (1). Since it was confirmed that the methyl bromide gas concentration was 5 ppm or less after 6 hours had elapsed, the switching damper (5) was switched to open to the outside to release the gas flow to the outside atmosphere.

  As is clear from the table, in Examples 1 and 2, the methyl bromide gas concentration decreased with the passage of time, and thus the methyl bromide gas could be rendered harmless quickly. As described above, according to the processing apparatus and the processing method of the present invention, it is possible to sufficiently suppress the emission of methyl bromide gas that promotes destruction of the ozone layer to the atmosphere, and to suppress the release of toxic substances to the atmosphere. Because it can, it can reduce the burden on the global environment and can fully contribute to the protection of the global environment.

It is the schematic which shows one Embodiment of the gaseous halogen compound processing apparatus of this invention. It is the schematic which shows an example (helical type) of the electrode structure of a pulse corona reactor. It is the schematic which shows a scrubber. It is the schematic which shows the other example of the electrode structure of a pulse corona reactor. It is the schematic which shows the further another example of the electrode structure of a pulse corona reactor. It is the schematic which shows the further another example (cylindrical type) of the electrode structure of a pulse corona reactor. (A) (b) (c) All are schematic views showing other examples of scrubbers. It is a graph which shows the suitable example of the voltage and current waveform of a pulse power supply. It is explanatory drawing of the gas process after the conventional fumigation process. It is the schematic of the activated carbon adsorption tower used with the conventional processing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gaseous halogen compound processing apparatus 2 ... Discharge plasma reactor (pulse corona reactor)
3 ... Scrubber 5 ... Switching damper 6 ... Fumigation warehouse 11 ... Pulse power supply 12 ... Discharge electrode 13 ... Counter electrode 42 ... Methyl bromide

Claims (15)

A decomposition treatment step for decomposing the halogen compound by contacting a gas stream containing a gaseous halogen compound with the discharge plasma;
And a halogen fixing step of forming a salt of the halogen and the metal by bringing a gas stream containing the decomposition product generated by the decomposition treatment into contact with a chemical solution containing metal ions. Halogen compound treatment method. A decomposition treatment step for decomposing the methyl bromide by bringing a gas stream containing methyl bromide gas into contact with the discharge plasma;
A halogen fixing step of forming a metal bromide salt by bringing a gas stream containing hydrogen bromide generated by the decomposition treatment into contact with a chemical solution containing metal ions. Processing method. A flow process for sending a gas stream containing methyl bromide gas after being used for fumigation treatment from a fumigation warehouse into a discharge plasma reactor;
A decomposition treatment step of decomposing the methyl bromide by bringing a gas flow containing the methyl bromide gas into contact with the discharge plasma in the discharge plasma reactor;
A halogen fixing step of forming a metal bromide salt by bringing a gas stream containing hydrogen bromide generated by the decomposition treatment into contact with a chemical solution containing metal ions;
A return flow step for returning the gas flow after the halogen fixing step into the fumigation warehouse,
A method for treating a gaseous halogen compound, wherein the circulation treatment comprising the flow feeding step, the decomposition treatment step, the halogen fixing step, and the return flow step is performed one or more times.   The method for treating a gaseous halogen compound according to any one of claims 1 to 3, wherein a chemical solution containing sodium ions is used as the chemical solution containing metal ions.   The processing method of the gaseous halogen compound of any one of Claims 1-3 which uses sodium hydroxide aqueous solution as a chemical | medical solution containing the said metal ion.   As the discharge plasma, non-equilibrium plasma generated by a pulse corona reactor that generates a pulse corona between both electrodes by applying a pulse voltage between a discharge electrode and a counter electrode that are spaced apart from each other is used. The processing method of the gaseous halogen compound of any one of Claims 1-5. A discharge plasma reactor for reacting a gas stream containing a gaseous halogen compound with the discharge plasma generated in the chamber;
An apparatus for treating a gaseous halogen compound, comprising: a scrubber for bringing a gas flow after reacting in the discharge plasma reactor into contact with a chemical solution containing metal ions. A pulse corona reactor for reacting a gas stream containing gaseous halogen compounds with a non-equilibrium plasma generated in the chamber;
An apparatus for treating a gaseous halogen compound, comprising: a scrubber for bringing a gas flow after reacting in the pulse corona reactor into contact with a chemical solution containing metal ions. Fumigation warehouse,
A pulse corona reactor for reacting a gas stream containing a gaseous halogen compound sent from the fumigation warehouse with non-equilibrium plasma generated in the vessel;
A scrubber for contacting the gas flow after reacting in the pulse corona reactor with a chemical containing metal ions;
In addition to introducing a gas flow sent from the scrubber, a switching damper capable of switching between a route for returning the gas flow to the fumigation warehouse and a route for releasing the gas flow to the atmosphere as it is. Equipment for treating gaseous halogen compounds.   In the pulse corona reactor, the distance between the discharge electrode and the counter electrode is set to 100 mm or less, the distance average electric field strength is set to rise at 10 V / cm / ns or more, and the maximum value is 5 kV / cm or more. The apparatus for processing a gaseous halogen compound according to claim 8 or 9, wherein the apparatus is set to apply a pulse high voltage at least 100 times per second.   In the pulse corona reactor, the counter electrode is formed in a spiral coil shape, while the discharge electrode is formed by a linear electrode twisted with a square wire, and the linear discharge electrode is opposed to the spiral coil shape. The processing apparatus of the gaseous halogen compound of any one of Claims 8-10 currently inserted and arranged in the spiral space of the electrode.   The apparatus for processing a gaseous halogen compound according to any one of claims 8 to 11, wherein a dielectric is coated on the surface of the counter electrode of the pulse corona reactor.   The gaseous halogen compound processing apparatus according to claim 12, wherein the dielectric is one or more dielectrics selected from the group consisting of ceramic, glass, and resin.   The apparatus for treating a gaseous halogen compound according to any one of claims 7 to 13, wherein a chemical solution containing sodium ions is used as the chemical solution containing metal ions.   The processing apparatus of the gaseous halogen compound of any one of Claims 7-13 in which sodium hydroxide aqueous solution is used as a chemical | medical solution containing the said metal ion.

Images