JP4628719B2 - Hazardous gas treatment device and cleaning method thereof - Google Patents

Description

  The present invention relates to a harmful gas treatment apparatus using a technology for decomposing and detoxifying harmful gases with plasma, and in particular, provides an apparatus that can easily clean an electrode that generates plasma.

  A harmful gas treatment apparatus using plasma discharges between electrodes, generates low-temperature plasma between the electrodes, and decomposes harmful gases by the plasma, but has the ability to purify various harmful gases. Various things have been developed to increase the energy saving effect.

An apparatus that treats harmful gas using such plasma is required to be developed that can efficiently decompose even a rare gas. An example of such a technique is disclosed in Patent Document 1.
JP 2001-340442 A

  In the technique disclosed in Patent Document 1, a dilute gas is condensed by an adsorption rotor and then passed between plasma electrodes to be decomposed.

  However, the one described in Patent Document 1 has a problem that, when decomposing a harmful gas containing an organic substance having a high polymerization property, the harmful gas polymerized by the plasma adheres to the electrode and contaminates the electrode. Examples of such substances that easily pollute the electrode include nonpolar aromatic hydrocarbons such as toluene, xylene, and styrene.

  If such a substance by-product adheres to the electrodes, the generation of plasma between the electrodes is hindered, and the ability to decompose harmful gases gradually decreases. For this reason, such devices sometimes need to disassemble and clean the electrodes. With this disassembly and cleaning, there is a problem that the operation of the apparatus must be stopped. Therefore, when it is impossible to stop the operation for a long time, it is necessary to prepare a spare electrode and perform cleaning and use alternately.

  Further, there is a problem that disposal cannot be performed unless the cleaning agent and cleaning water used for cleaning are performed, and the associated costs and labor are required.

  An object of the present invention is to provide a harmful gas treatment apparatus that can be cleaned by a simple operation when an electrode is soiled and does not require a cleaning agent or cleaning water.

  In order to solve the above-described problems, the present invention is provided with a cleaning mode in which a vapor of an organic substance that contains oxygen atoms and is a gas or a liquid at normal temperature is flowed while generating plasma.

  Since the harmful gas treatment apparatus of the present invention is configured as described above, when an organic substance (cleaning agent) that contains oxygen atoms and is gaseous or liquid at normal temperature is decomposed by plasma, the organic substances attached to the electrode by the oxygen atoms contained therein The electrode can be cleaned by oxidative decomposition.

  At this time, the electrode can be cleaned by simply flowing a cleaning agent while generating plasma without disassembling the electrode. Therefore, it is not necessary to use a cleaning liquid or the like, and there is no problem of processing of the cleaning liquid.

  As the cleaning agent, a substance having a low molecular weight and a strong polarity is suitable. For example, if methanol or the like to be discarded is used, cleaning can be performed together with the disposal of methanol, and the operation of the harmful gas processing apparatus can be performed extremely rationally. Can do.

  Further, since cleaning can be performed without disassembling the electrodes, the time for stopping the operation for cleaning is short, and it is not necessary to prepare a plurality of electrodes for cleaning.

  The invention according to claim 1 of the present invention includes an electrode and a power source for generating plasma between the electrodes, and is configured to cause harmful gas to flow between the electrodes, and generates plasma. In addition, since the cleaning mode is provided in which an organic vapor that is a gas or a liquid at normal temperature and contains oxygen atoms is provided, the impurity can be easily removed when the impurity adheres to the electrode.

  Embodiments of the harmful gas treatment apparatus of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a flow chart of the harmful gas treatment apparatus of the present invention. The harmful gas generation source 1 is, for example, a painting booth, and generates harmful gases such as toluene and xylene, which are paint solvents. Alternatively, the harmful gas generation source 1 is a semiconductor wafer mask removing process or a place where other harmful gases are generated.

  The suction port of the blower 2 is connected to the harmful gas generation source 1 via the switching valve 3 and sucks gas from the harmful gas generation source 1. The discharge port of the blower 2 is connected to the plasma decomposition apparatus 4.

  The cleaning agent tank 5 stores a cleaning agent such as methanol, and the cleaning agent is supplied from the cleaning agent tank 5 to the vaporizer 6. The vaporizer 6 vaporizes a cleaning agent such as methanol supplied from the cleaning agent tank 5, and includes, for example, an ultrasonic vaporizer and a heater. The vaporizer 6 is connected to the suction port of the blower 2 via the switching valve 3.

  The plasma decomposition apparatus 4 is as shown in FIGS. That is, the plasma decomposing apparatus 4 has a plurality of electrodes 9 made of electrode conductors 8 such as stainless steel plates sandwiched between a pair of insulating plates 7 and 7 such as mica plates, and an adsorption inserted between the electrodes 9. It has a body 10.

  One end of the electrode conductor 8 is exposed from the insulating plates 7 and 7, and a pair of conductive wires 11 and 11 are connected to the exposed portion. Further, every other exposed portion of the plurality of electrode plates 8 is provided alternately. Accordingly, the conductive wires 11 and 11 are passed through the both ends of the electrode conductor 8 from the top to the bottom, and by alternately connecting the electrode plate 8 and the pair of conductive wires 11 and 11, all the electrode conductors 8 and the pair of conductive wires 11 are connected. , 11 can be connected.

  A high voltage pulse power supply 12 having a voltage of about 12 Kv is connected to the pair of conductive lines 11, 11, thereby generating plasma between the electrode 9 and the other electrode 9.

  Here, what is shown in FIG. 2 and FIG. 3 is an adsorbent 10 in which an inorganic adsorbent such as zeolite is supported on a corrugated ceramic sheet. The adsorbent 10 shown in FIG. 4 is a combination of a formed ceramic sheet and a flat ceramic sheet.

  In normal operation, the switching valve 3 is operated so that harmful gas from the harmful gas generation source 1 such as a semiconductor manufacturing plant is guided to the suction port of the blower 2. Then, the harmful gas from the harmful gas generation source 1 is sent to the plasma decomposition apparatus 4 by the blower 2 through the switching valve 3.

  Here, in the plasma decomposition apparatus 4, plasma is generated between the electrode 9 and the other electrode 9, and harmful gas molecules adsorbed on the adsorbent 10 are decomposed by the plasma.

  Depending on the type of harmful gas, a polymerization reaction also occurs with this decomposition. The polymerized molecules are generally substances that are difficult to decompose and gradually accumulate on the surface of the insulating plate 7. As the deposition progresses, the deposit gradually carbonizes and inhibits the generation of plasma.

  Here, the switching valve 3 is operated so that the vaporizer 6 and the blower 2 are in communication. Then, a cleaning agent such as methanol is supplied from the cleaning agent tank 5 to the vaporizer 6. The cleaning agent is vaporized by the vaporization device 6 and sent to the plasma decomposition device 4 by the blower 2.

  The vaporized cleaning agent is easily decomposed by the plasma decomposition apparatus 4. Along with the decomposition, oxygen atoms in the molecule are given to the polymer, and the polymer is decomposed. As a result, the polymer adhering to the surface of the electrode 9 is removed.

  In the above example, methanol is used as the cleaning agent, but ethanol or the like is also suitable. In the applicant's test, the cleaning effect was sufficiently exhibited even with methyl ethyl ketone having a solubility parameter of 9.3, but ethyl acetate (solubility parameter 9.1) or butyl acetate (solubility parameter 8.5) having a solubility parameter lower than this. However, the cleaning effect was not fully exhibited.

  In this embodiment, an example having the cleaning agent tank 5 to the vaporizer 6 is shown. However, when there is a plant in which an organic solvent gas suitable as a cleaning agent is generated, the organic solvent gas is removed from the plasma decomposition apparatus. If it is made to flow to 4, the process of the organic solvent gas and the cleaning of the electrode 9 can be performed simultaneously.

  In the above embodiment, the cleaning mode for supplying the cleaning agent and the decomposition mode for decomposing the harmful gas are switched. However, the cleaning mode for supplying the cleaning agent during the operation of the decomposition mode is set in parallel. It is also possible to do this.

  The present invention decomposes harmful gases by plasma, and decomposes and removes by-products deposited on the electrode by decomposing the cleaning agent with plasma when a by-product accompanying the decomposition is deposited on the electrode. To provide a harmful gas treatment device capable of

It is a flowchart which shows the Example of the noxious gas processing apparatus of this invention. It is a front view which shows the plasma decomposition apparatus used for the noxious gas processing apparatus of this invention. FIG. 3 is a partially enlarged view of FIG. 2. It is the elements on larger scale of the plasma decomposition apparatus of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Harmful gas generation source 2 Blower 3 Switching valve 4 Plasma decomposition apparatus 5 Cleaning agent tank 6 Vaporization apparatus 7, 7 Insulation board 8 Electrode conductor 9 Electrode 10 Adsorbent 11 Conductive wire 12 High voltage pulse power supply

Claims (3)

It has an insulated plate-like electrode and a power source for generating plasma between the electrodes, and allows harmful gas to flow between the electrodes, and contains oxygen atoms while generating plasma. A liquid organic vaporizer is provided so that a polar organic vapor that is a gas or liquid at normal temperature flows, and a cleaning mode is provided for cleaning substances accumulated on the electrodes that have been polymerized along with the decomposition of harmful gases. Hazardous gas treatment equipment provided. Harmful gas treatment apparatus according to claim 1, wherein organic material containing oxygen atoms is methanol. It has an insulated plate-like electrode and a power source for generating plasma between the electrodes, and allows harmful gas to flow between the electrodes, and contains oxygen atoms while generating plasma. A cleaning method for a harmful gas treatment apparatus, wherein a substance which is polymerized as the harmful gas is decomposed and accumulated on the electrode is flowed by flowing a vapor of a polar organic substance which is a gas or liquid at normal temperature.

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