JP4570847B2 - Method and apparatus for halogen-containing compound decomposition by plasma reaction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for quickly and efficiently decomposing a halogen-containing compound in a safe and simple manner when handling it by generating a high-temperature plasma using a halogen-containing compound such as Freon and water as raw materials.
[0002]
[Prior art]
Freon (CFC), halon, carbon tetrachloride, trichloroethane, methyl bromide, hydrochlorofluorocarbon (HCFC) and the like are considered to be substances that destroy the ozone layer. In addition to carbon dioxide, methane, and nitrous oxide, hydrofluorocarbon (HFC), perfluorocarbon (PFC), and fluorine hexafluoride compounds are designated as global warming target gases. Measures to solve the problems of halogen-containing compounds that have a major impact on both ozone-depleting substances and global warming are the development of alternative technologies such as alternative substances and the recovery and decomposition technologies for halogenated compounds currently used. In development.
[0003]
By the way, since CFC, HCFC, and HFC, which are typical fluorine-containing compounds as halogen-containing compounds, are chemically stable, it was once considered difficult to decompose them. Equipment has been developed.
[0004]
Major fluorine compound decomposition techniques include a combustion method, a plasma method, and other non-combustion methods. In these decomposition treatment methods, a method is generally used in which chlorofluorocarbon is decomposed in a heat decomposition portion such as combustion or plasma, and the generated highly corrosive halogen compound gas is separately subjected to wet neutralization treatment. This method has the advantage that the existing heating method and neutralization method can be used, but the disadvantage is that the running cost increases due to corrosion of the piping by the generated corrosive gas, complicated wastewater treatment of neutralized water, neutralization Increase in facility size and initial cost due to processing equipment. In particular, with regard to the decomposition treatment of halons, it is in the verification test stage and has not yet been put into practical use.
[0005]
Combustion methods include reactor cracking method, gas / fume oxidation method, rotary kiln method, liquid injection method, municipal waste incineration method, and cement kiln method.
[0006]
The reactor cracking method is a method in which hydrogen, oxygen, and CFC are decomposed with a high-temperature burner of 2300K or higher. The Solvay company in Frankfurt city decomposes CFCs and halons by reactor cracking.
[0007]
The gas / fume oxidation method is a method of decomposing CFC using a combustion flame of natural gas or the like. Iones Chemical Co., Ltd. in Hiroshima Prefecture decomposes CFC at 165 kg / hour and halon at about 15 kg / hour.
[0008]
The rotary kiln method uses a rotary kiln for waste treatment in combination with a halon decomposition process. Liquid or gaseous halon / fluon is injected and decomposed together with a combustion aid at a high temperature of 1773K. This decomposition facility has a secondary combustion chamber and a tertiary combustion chamber, and performs further combustion at 1123 to 1373K. The treatment of the acidic exhaust gas is carried out by rapidly cooling to 353 K with a cooling tower, thereafter performing alkali cleaning with a two-stage washing tower, and removing dust with a two-stage wet electrostatic precipitator. The advantage of this method is that it is possible to use a rotary kiln for waste disposal nationwide. However, a disadvantage is that highly corrosive halogen compounds generated by the decomposition of halon and flon damage the kiln furnace wall. Maintenance costs are greatly increased, and the frequency of maintenance is increased, which is said to hinder the disposal of general waste, which is the original use, and it is difficult to arrange the acceptance of waste disposal contractors on site. In Sweden, there is an example in which WMI-SAKAB company decomposed CFCs and halons using a rotary kiln.
[0009]
In the liquid injection method, there is a chlorofluorocarbon decomposition facility owned by Teijin Fluorochemical Co., Ltd. (currently Ineos Chemical Co., Ltd.), which is one of the Ministry of the Environment model commercialization research. This facility thermally decomposes a mixed gas of halon, flon, water vapor and air using LPG as a combustion aid. The inside of the cracking furnace is at a high temperature of 1473K or higher, and the temperature is kept constant by supplying a combustion aid. The acid gas in the exhaust gas is absorbed in water and neutralized with slaked lime.
[0010]
The municipal waste incineration method is a method of decomposing fluorine compounds in a municipal waste incinerator such as a moving bed type stoker furnace.
[0011]
The cement kiln method is an economical method because it reacts cement, which is an alkali material, with fluoride and chloride generated by the decomposition of CFCs. However, since the strength of cement decreases, the proportion of chlorine that can be mixed is about 100 ppm, and the amount that can actually be mixed is very limited.
[0012]
As in the present invention, chlorofluorocarbon decomposition using plasma includes a direct current plasma method, a high frequency plasma method, and a microwave plasma method. These are methods for decomposing chlorofluorocarbons by utilizing the high temperature of about 5000K which the plasma has.
[0013]
As a method using DC plasma, there is a CFC and halon decomposition process (PLASCON process) by SRL Plasma Limited of Australia. In this method, water vapor and CFC or halon are supplied into the argon plasma and decomposed in the plasma. Murphy et al. Decomposed PCB, CFC and halon using Ar arc plasma. This is H to plasma₂O or O₂After exhausting and decomposing, exhaust gas is quenched with water. It has been reported that when CFC-12 is decomposed, the amount of Freon up to 14 mol / kWh can be decomposed by 99.99%, and the same result can be obtained even when CFC-12 is decomposed. In addition, as a NEDO contract research under the Ministry of International Trade and Industry (currently the Ministry of Economy, Trade and Industry), Asahi Glass Co., Ltd. This is to thermally decompose halon 1301 using arc plasma of 5000K or more. The decomposition gas of halon contains F and Br, and these gases are subjected to scrubber and wet neutralization treatment. Although it is said that the decomposition rate of halon has reached 99.99%, it has not been put into practical use in terms of cost. There is also a method using nitrogen plasma instead of argon gas. Fluorine compound and water vapor are supplied into nitrogen plasma by DC discharge. Since it is difficult to generate pure water vapor plasma with direct current discharge plasma, gas is first generated using a gas that easily generates plasma such as argon or nitrogen, and then water vapor and halogen-containing compound are supplied to it. Therefore, it must be a method of disassembling.
[0014]
As a method using high frequency plasma, there is a method of treating CFC or HCFC in water vapor plasma possessed by Ichikawa Environmental Engineering Co., Ltd. This is a method having a processing speed of 50 kg / hour using an electric power of about 100 kW. In addition, Uematsu et al. Developed a system that rapidly cools high-temperature exhaust gas to 80 ° C or less at once by performing catalytic decomposition of CFC / halon and water vapor using high-frequency plasma. CFC and halon have a decomposition capacity of 50 kg / h or more, a decomposition rate of 99.999% or more, and decomposition exhaust gas is less than UNEP guidelines.
[0015]
As a method using microwave discharge, there is a method in which water vapor and a fluorine compound developed by Mitsubishi Heavy Industries, Ltd. are supplied into plasma and decomposed. With a power of about 2 kW, it has a processing speed of 2 kg / hour.
[0016]
As a method for decomposing a halogen-containing compound by a plasma reaction method using plasma energy, a method using water plasma is considered suitable. This is because, in addition to the reason that water used as a plasma gas is inexpensive, it is possible to combine halogen and carbon generated by decomposition of a halogen-containing compound with hydrogen and oxygen generated from water plasma, respectively. .
[0017]
As a method for generating water plasma using direct current discharge, there are a method of supplying liquid water into the plasma and vaporizing the water in the plasma, and a method of supplying water vapor into the plasma. In both cases, it is difficult to obtain pure water plasma, and usually only plasma composed of a mixed gas of argon and water can be obtained. This is because water is jetted downstream of the DC discharge plasma using argon gas or the like. This method is not an efficient method because water does not pass through the discharge region where the plasma is the hottest.
Furthermore, in this case, pure water plasma cannot be obtained. Here, argon is excited by direct current discharge to become argon plasma, and is considered to have a catalytic plasma assist action of repeatedly returning to argon after transferring energy to water. The use of nitrogen gas instead has also been studied.
[0018]
In the case of the former (liquid water supply), vaporization of water in the plasma is unstable, and it is difficult to obtain a stable plasma. In the latter case, there are problems of stable supply of water vapor into the plasma, stability of the plasma, and the need for a separate steam generator. Conventionally, as a method for solving these problems, in the case of plasma by direct current discharge, operation was performed under reduced pressure as a method for stably supplying water vapor into the plasma. Still, there were problems with plasma stability. In this case, since a pressure reducing device is required, the size of the device is increased and the entire device becomes expensive. In addition, since the decomposition is always performed under a reduced pressure condition, it is complicated compared to the operation under atmospheric pressure.
[0019]
As a method for generating pure water plasma, there are high-frequency discharge plasma and microwave discharge. In these methods, since water vapor previously vaporized is injected into high-temperature plasma, it is difficult to supply stable water vapor, and thus it is difficult to generate stable water plasma. Furthermore, in this case, the power supply device becomes large and expensive as compared with DC discharge plasma. In order to decompose halogen-containing compounds by the plasma reaction method, it is necessary to supply halogen-containing compounds together with water, and it is more difficult to stably supply water and halogen-containing compounds into the plasma and to generate stable plasma. Met.
[0020]
In the case of decomposing a halogen-containing compound by water plasma, it is important to stably generate plasma using water as a raw material. Therefore, it is a problem to stably and quickly generate plasma composed of water vapor. Furthermore, it is a problem to develop an apparatus that easily generates water plasma without requiring a gas cylinder or a steam generator.
[0021]
In order to decompose a halogen-containing compound using water plasma, it is necessary to supply the halogen-containing compound stably in a high-temperature plasma. In this case as well, it is important to pass the halogen-containing compound through the high temperature region of the plasma, but this is difficult in the case of DC plasma. Therefore, in order to decompose the halogen-containing compound using water plasma, there are many problems in applying to the industrial field in the conventional technology from the viewpoint of efficiency.
[0022]
In order to generate plasma, a gas cylinder that contains a gas for generating plasma is usually required. In addition to the plasma generator, a gas cylinder is required, the apparatus becomes large, and it may be difficult to generate plasma in a limited place. Furthermore, when supplying water vapor to generate water plasma, it is necessary to start up an external steam generator and keep the piping warm to prevent water vapor condensation. take time. Furthermore, since the entire apparatus is large, it is difficult to carry a water plasma generator composed of these apparatuses.
[0023]
As a method for generating water plasma using direct current discharge, there are a method of supplying liquid water into the plasma and vaporizing the water in the plasma, and a method of supplying water vapor into the plasma. In both cases, it is difficult to obtain pure water plasma, and usually only plasma composed of a mixed gas of argon and water can be obtained.
[0024]
  As a result of diligent research on a method for decomposing a halogen-containing compound by a plasma reaction, the present inventors have found a method for vaporizing a liquid or gas-containing halogen-containing compound and water and directly decomposing the halogen-containing compound by using the gas plasma. The present invention has been achieved. That is, the present invention relates to the thermal energy of an electrode that generates high-temperature plasma.Or thermal energyThis is achieved by promoting the vaporization of the liquid halogen-containing compound and water using the action of the vibration plate that vibrates at an ultrasonic frequency and reacting these gases in the discharge region. Especially power supplyAsUsing a simple and inexpensive DC power supplyAndThe halogen-containing compound is decomposed by a water plasma generator that does not require a gas cylinder or a steam generator.
[0025]
A point to be considered in the method of decomposing a halogen-containing compound by a plasma reaction is to supply water vapor and a halogen-containing compound stably in a high-temperature plasma and react efficiently. That is, when supplying water vapor into the atmospheric pressure plasma, it is necessary to heat the pipe for introducing the water vapor to 100 ° C. or higher. Further, in order to react the halogen-containing compound with water in the plasma, It is necessary to pass the halogen compound through the high temperature region of the plasma. If water vapor condenses in the pipe, or if the supply position of water vapor or halogen-containing compounds to the plasma is offset or cannot be supplied stably, the plasma state becomes unstable, and in extreme cases the plasma disappears Resulting in.
[0026]
[Problems to be solved by the invention]
The present invention has been made in view of these points, and its purpose is to use a halogen-containing compound and water as raw materials, and the action of a diaphragm that vibrates at the thermal energy of an electrode generating plasma and the frequency of ultrasonic waves. To vaporize the halogen-containing compound and water, and to realize a method and apparatus for stably supplying the plasma into the plasma. In particular, the halogen-containing compound and water are efficiently reacted to generate a plasma reaction. An object of the present invention is to realize a method and an apparatus for decomposing a halogen-containing compound efficiently, simply and rapidly without generating soot and a wax-like substance.
[0027]
[Means for Solving the Problems]
  The above-mentioned problem is (1) “the arc generated between the cathode and the anode of the present invention.Halogen-containing compoundsAnd water supply, hot plasmaGenerateA method,Given to the cathode and anodeenergyBy,AboveThe halogenated compound and water are vaporized, and the resulting gas isIn the discharge region between the cathode and anodeA method of decomposing a halogen-containing compound by reacting. ";
(2) “By the action of the diaphragm that vibrates at the frequency of ultrasonic wavesHalogenated compounds and waterEvaporatethingA method for decomposing a halogen-containing compound as described in (1) above. ";
(3) “The halogen-containing compound is chlorofluorocarbon, halon, hydrofluorocarbon, hydrochlorofluorocarbon, trichloroethane, PCB, SF.₆Said (1) characterized by being selected from the group ofOr(2) A method for decomposing the halogen-containing compound described in item (2). Is achieved.
  In addition, the above object is (4) “nozzle shape” of the present invention.Electrodes andStickelectrodeDC plasma torch consisting of a halogen-containing compound and waterStorage roomAnd contain theseAnd opened at the opening of the nozzle-like electrodecontainerThe halogen-containing compound and water are vaporized by the energy applied to the DC plasma torch, led to a discharge region generated by the DC plasma torch, and exit from the opening.Halogen-containing compounds by plasma reaction methodDecompositionapparatus. ";
(5) "It has a diaphragm that vibrates at an ultrasonic frequency,The halogen-containing compound and waterSaidVaporization is promoted by the action of the diaphragm.thingAn apparatus for decomposing a halogen-containing compound as described in (4) above. ";
(6) “The halogen-containing compound is chlorofluorocarbon, halon, hydrofluorocarbon, hydrochlorofluorocarbon, trichloroethane, PCB, SF.₆(4) characterized in that it is selected from the groupOr(5) The apparatus which decomposes | disassembles the halogen-containing compound as described in a term. Is achieved.
[0028]
Hereinafter, the present invention will be described in detail and specifically with reference to the drawings.
When a high voltage is applied between the cathode and the anode and an instantaneous short circuit is performed, arc discharge, that is, thermal plasma is generated, and the water in the tank is instantly evaporated by the generated arc heat (H₂O (l) → H₂O (g)) and dissociated (H in the arc discharge region)₂O (g) → 2H + O), ionization (2H + O → 2H)⁺+ O⁺+ 3e) reaction. In this ionization state, since the electric conductivity is good, a large current flows constantly, and the thermal plasma state is maintained. In this case, the plasma temperature is about 10,000 ° C.
[0029]
In the plasma generation method and apparatus of the present invention, the high-temperature region of direct current discharge is not only used for plasma formation from a gas obtained from a halogen-containing compound and water, but also uses the energy generated by the electrode generating the arc. Thus, when the organic material and water are vaporized and led to the high temperature region of the discharge, it is used as an auxiliary of an adjustable piezo vibrator, and in particular, the liquid organic material and water are efficiently reacted to generate a plasma reaction. Therefore, it is possible to realize a method and an apparatus for decomposing a halogen-containing compound efficiently, simply, and quickly without involving soot and the formation of a wax-like substance.
[0030]
The plasma generator according to the present invention is particularly characterized in that the halogen-containing compound and water are vaporized by utilizing the action of a diaphragm that vibrates at the frequency of thermal energy and ultrasonic waves generated by the electrodes.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
The apparatus of the present invention has been made in view of the above background, and a liquid plasma generation apparatus using a novel working liquid transport system is provided, and it is efficient without the generation of soot and wax-like substances, Provided is a liquid plasma generator capable of easily and rapidly decomposing halogen-containing compounds at extreme locations.
[0034]
  FIG. 2 shows the plasma generator of the present invention.1 exampleIs shown. In the apparatus of this example, the plasma torch of this embodiment isFIG.The following points are different from the known plasma torch described in 1).
(1) Taking out the moisture absorbing material 7 from the container 6 for working fluid, partitioning the interior of the container with a partition member 25, and providing a water storage chamber for storing an organic compound containing halogen and water 24 directly in the internal space on the rear end side. Formed.
(2) An organic compound containing halogen is added to the torch main body 1 side from the water containing chamber by the partition walls 26 and 27 provided additionally, and a misting chamber for misting the organic compound containing halogen and water by ultrasonic vibration is provided. A piezoelectric element, for example, a piezoelectric element 28 as an ultrasonic vibrator, for example, is disposed here. An external drive circuit and a switch (not shown) for applying a voltage from an external power source are connected to the piezo element 28.
(3) In order to supply the organic compound containing halogen, the organic compound containing halogen in the water storage chamber, and water to the mist chamber, a felt 29 serving as a water transmission member is disposed across the two chambers. The end of the felt 29 on the mist chamber side was positioned so as to be in contact with the piezo element 28.
(4) The porous heat conductive material 8 was shortened and the shape was changed as described later. Furthermore, the shape of the link 9 was also changed with this shape change.
(5) A plurality of heat-resistant pipes 30 connected the gap between the outer peripheral surface of the porous thermal conductive material 8 and the inner peripheral surface of the torch body 1 and the mist chamber.
(6) The anode 2 and the cathode 4 may be used as the cathode 2 and the anode 4 with the voltages reversed.
[0035]
  3 (a) and 3 (b), the porous thermal conductive material 8 is the porous heat shown in FIG.Conductive material 8On the other hand, only the part facing the inner peripheral surface of the torch main body 1 was left, and the rear end side was cut from that. Innumerable protrusions 31 are provided spirally on the outer peripheral surface. Further, a taper is provided at the contact tip with the link 9, and a plurality of tangential groove passages 32 are formed in the taper. And the rear end surface shape of the link 9 was made into the reverse taper shape so that the said taper part may be contacted. A plurality of (eight in the illustrated example) groove passages 10 a are formed on the outer peripheral surface of the link 9. Further, a groove groove 10 for a passage is formed by continuing only a part (three in the illustrated example) of the plurality of grooves 10a on the outer peripheral surface at the tip tapered portion that contacts the annot 2 of the link 9. .
[0036]
In FIG. 3C, a flat piezo element 28 was used as the piezo element, and the felt ends were overlapped so as to contact the surface. A square hole 33 was formed at the felt end. Instead of such a shape, a plurality of round holes 34 may be formed as shown in FIG. Further, one end of the heat-resistant pipe may be connected to the round hole 34 as indicated by a virtual line in FIG.
[0037]
In the above configuration, when the plasma torch of the present embodiment is used, first, the stopper 17 is removed and the organic compound containing halogen in the container 6 from the working fluid replenishment hole 18 and the halogen as the working fluid in the water storage chamber. Add water and organic compound. The organic compound containing halogen, the organic compound containing halogen in the water storage chamber, and the water 24 are supplied to the mist chamber through the felt 29, and the organic compound containing halogen at the felt end overlapping the upper surface of the piezoelectric element 27. Water is retained, and the holes 33 formed in the felt 29 are also filled with an organic compound containing halogen and water. Thereafter, the stopper 17 is attached. In this state, the external power supply is turned on to start voltage application to the anode 2 and the like. Then, the button 16 is pressed, the cathode holder 3 is moved, and the cathode 4 at the tip is brought into contact with the anode 2. Then, the pressing of the button 16 is stopped. When the push-in is stopped, the button 16 is pushed back by the urging force of the spring 15, and the cathode holder 3 also returns to the initial position along with this. With this return, arc discharge starts in the discharge chamber 10 when the cathode 4 moves away from the anode 2. The contact portion between the lid 14 and the plastic cover 19 is a screw. By rotating this screw by hand, the positional relationship between the lid 14 and the plastic cover 19 can be adjusted. Thereby, the distance between the anode 2 and the cathode 4 can be adjusted. Therefore, the optimal length of the arc can be obtained.
[0038]
  In this embodiment, as the external power source is turned on, a voltage is applied to the driving circuit of the piezo element 28 as the button 16 is pressed. Start ultrasonic vibration. By this ultrasonic vibration, the organic compound containing halogen and water held at the felt end portion on the piezo element are misted. In particular, the halogen-containing organic compound and water filled in the hole 33 formed at the felt end are efficiently misted. Then, the mist of the organic compound containing water and water is passed through the heat-resistant pipe 30 to generate porous heat.Conductive material 8To the gap between the outer peripheral surface of the torch body 1 and the inner peripheral surface of the torch body 1.
[0039]
  Then, the heat generated by the current flowing through the arc discharge is transferred to the porous heat conductive material 8 through the heat conductive link 9. This results in porous heatConductive material 8A mist of water containing an organic compound containing halogen and water supplied to the gap between the outer peripheral surface of the torch body and the inner peripheral surface of the torch body 1 becomes steam. Then, excessive pressure is generated, and this vapor enters the discharge chamber 11 through the passage 10a on the outer peripheral surface of the link 9 and the groove passage 10 on the tip tapered portion, as indicated by symbol A in FIG. . In addition, the vapor | steam which entered into what is not continuing to the channel | path 10 of a front-end | tip taper part among the some channel | paths 10a of the outer peripheral surface of the link 9 flows back. In addition, due to the excessive pressure, a part of the vapor is porous heat as indicated by a symbol B in FIG.Conductive material 8It directly enters the discharge chamber 11 through the passage 32 of the tip taper portion. Backflow abovesteamPart of this also directly enters the discharge chamber 11 through this passage 32. Then, the vapor that has entered the discharge chamber 11 is turned into plasma and blown out through the hole in the central axis of the anode 2. This stabilizes the arc column and simultaneously cools the anode 2 and the cathode 4.
[0040]
According to the plasma torch according to the above embodiment, the halogen-containing organic compound and water misted by the ultrasonic vibrator are supplied to the torch body 1 side, so the halogen-containing organic compound and water supply to the torch body side. Can be controlled by driving control of the ultrasonic transducer. Therefore, for example, a stable organic compound containing halogen and water can be supplied by continuous driving. In addition, a stable plasma jet flow can be injected immediately after the start of operation. In contrast,FIG.In the known plasma torch, the organic compound containing halogen in the container 9 fluctuates depending on the environment and use history, and the organic compound containing halogen to the torch body 1 side due to the water partial state and the like, steam is generated by the water supply state and heating. The state is influenced, and the plasma jet flow tends to become unstable immediately after the start of operation.
[0041]
Further, in the plasma torch of the present embodiment, the moisture absorbing material 7 is not in a state of being absorbed by the moisture absorbing material 7, but the organic compound containing halogen and the organic compound containing halogen and water are accommodated directly in the water accommodating chamber. As much as 7 is not used, a larger amount of halogen-containing organic compound and water capacity can be secured. Therefore, the internal volume of the whole plasma torch can be reduced or the capacity of the stored water can be increased.
[0042]
Note that the liquid plasma apparatus according to the above embodiment can be held and handled, but the present invention can also be applied to a stationary liquid plasma apparatus. Moreover, although the plasma apparatus which concerns on the said embodiment is a thing of the plasma jet which spouts as a plasma jet stream, or a non-transferable arc production | generation type, this invention is applicable also to the type which produces | generates a transferable arc. Further, in the above embodiment, in order to cause arc discharge, a method is adopted in which a current is passed through the cathode and the anode in contact with each other, and then the electrodes are separated. Instead, a high frequency high voltage is applied between the electrodes. The present invention can also be applied to a method of applying ionization to gas between electrodes, a method of short-circuiting between electrodes with a thin wire, and using an arc when a wire is fused by current as seed plasma.
[0043]
In the conventional plasma generator using direct current discharge, the electrode becomes high temperature, so that the electrode is protected by cooling water so as not to melt. However, the energy added to the plasma is lost by the cooling water, and the energy actually given to the plasma is about 30% of the added energy. However, since the plasma generator according to the present invention uses the energy generated at the electrode for vaporizing the halogen-containing compound and water, the energy efficiency applied to the plasma generator is good. Therefore, it is a big feature that the energy efficiency of the whole hydrogen generator is good.
[0044]
A feature of hydrogen production by water plasma is that a rapid production process can be started. Since an external steam generator and piping heat insulating device are not required, water plasma can be quickly generated and decomposed when the halogen-containing compound needs to be decomposed. If it is necessary to stop the apparatus for some reason, the apparatus can be safely and urgently stopped by stopping the supply of power to the power source generating the water plasma. According to the present invention, the amount of the halogen-containing compound can be quickly decomposed according to the necessity of the decomposition of the halogen-containing compound, so that the storage facility for the halogen-containing compound can be minimized.
Furthermore, since the entire apparatus is small and light, it is easy to carry the apparatus as needed.
[0045]
As described above, the method for decomposing a halogen-containing compound by the plasma reaction method based on the invention described in the item (1) of the present invention is a conventional method in which water vapor or a halogen-containing compound is introduced into the plasma in a gaseous state in the plasma. The method is characterized in that the halogen-containing compound and water are used as raw materials and these liquids are vaporized by the energy of an electrode for generating plasma, and the gas is directly guided to the discharge region.
[0046]
In the invention described in item (2), the type of halogen-containing compound is referred to, and the halogen-containing compound is flon, halon, hydrofluorocarbon, hydrochlorofluorocarbon, trichloroethane, PCB, SF.₆This is a method for decomposing a halogen-containing compound by the plasma reaction method according to item (1), which is selected from the group consisting of:
[0047]
Further, the halogen-containing compound decomposition apparatus based on the plasma reaction according to the invention described in item (3) includes a direct current plasma torch comprising a copper nozzle-like anode and a cathode made of copper rod-like and hafnium alloy tips. A vessel containing a halogen-containing compound that is vaporized using the action of a vibration plate that vibrates at the frequency of thermal energy and ultrasonic waves generated by these electrodes, and a flow that guides these gases to the discharge part. It is characterized in that it is provided with a path, a gas outlet port obtained by the reaction, and a container for storing them. The voltage for stably generating water plasma by the DC power supply is about 100V, and the current is about 5A. When the halogen-containing compound is soluble in water, the halogen-containing compound is put in a container. When the halogen-containing compound is insoluble in water, a vapor mixture of the halogen-containing compound and water is obtained in separate containers. This container contains 100 cm of halogen-containing compound aqueous solution.³The degree is accommodated to obtain a mixed vapor of halogen-containing compound and water. In either method, the conventional method requires a plasma generator and a separate vaporizer to evaporate the liquid. However, in this device, the halogen-containing compound and water are evaporated by the energy generated at the plasma electrode. Therefore, no special vaporizer is required other than the plasma generator.
[0048]
Furthermore, in the invention described in item (4), the kind of halogen-containing compound is referred to, and the halogen-containing compound is flon, halon, hydrofluorocarbon, hydrochlorofluorocarbon, trichloroethane, PCB, SF.₆The apparatus for decomposing a halogen-containing compound by a plasma reaction according to item (3), which is selected from the group consisting of:
[0049]
A method for efficiently reacting a halogen-containing compound and water by a high-temperature plasma by a plasma reaction and decomposing the halogen-containing compound easily and rapidly is based on the following reaction. Specific reaction examples are shown below.
[0050]
When CFC-11 is used as the halogen-containing compound, the reaction represented by the following formula occurs in plasma.
[0051]
[Chemical 1]
CCl₃F + 2H₂O → CO₂+ 3HCl + HF
When CFC-113 is used as the halogen-containing compound, the reaction represented by the following formula occurs in plasma.
[0052]
[Chemical 2]
C₂Cl₃F₃+ 3H₂O → CO₂+ CO + 3HCl + 3HF
When using Halon 1301 as the halogen-containing compound, the reaction represented by the following formula occurs in plasma.
[0053]
[Chemical 3]
CBrF₃+ 2H₂O → CO₂+ HBr + 3HF
When using Halon 1211 as the halogen-containing compound, the reaction represented by the following formula occurs in plasma.
[0054]
[Formula 4]
CBrClF₂+ 2H₂O → CO₂+ 1 / 2HBr + 1 / 2HCl + HF
[0055]
A gas for generating high-temperature plasma is generated by vaporizing water and a halogen-containing compound with energy generated by a high-temperature electrode. The gas thus vaporized reacts in a high-temperature plasma, and chlorine, fluorine, or bromine contained in the halogen-containing compound becomes hydrogen chloride, fluorine chloride, or bromine chloride, respectively. Therefore, it is possible to decompose a halogen-containing compound using water selected from those selected from the group of various halogen-containing compounds described in claim 2.
[0056]
When the halogen-containing compound is soluble in water, an aqueous solution of these halogen-containing compounds is put in a container to obtain a mixed vapor of the halogen-containing compound and water. In this case, the composition of the gas obtained by the reaction can be controlled by adjusting the concentration of the halogen-containing compound in the aqueous solution. When the halogen-containing compound is insoluble in water, the halogen-containing compound and water are put in separate containers to obtain a mixed vapor of the halogen-containing compound and water.
[0057]
In addition to the above, when the halogen-containing compound is soluble in water, it is dissolved in water, and this is atomized into a mist form in an inert gas such as argon, and this is led to a space where an arc is generated. It is also possible to use a method of decomposing a halogen-containing compound by converting it into a plasma with the energy of. Mist is generated by the action of a diaphragm that vibrates at an ultrasonic frequency by a piezoelectric element. Mist water fine particles uniformly contain a halogen-containing compound and can be transported together with argon gas. This is guided to the arc chamber by a pipe, and thus the arc chamber is filled with a mist of water uniformly containing argon gas and a halogen-containing compound. Mist water fine particles are easy to vaporize because of their small diameter. When an arc is generated between the electrodes in the arc chamber, the mist is vaporized in the vicinity of the arc by the heat of the arc and further decomposed into a plasma state. Water fine particles are vaporized, and water vapor containing a halogen-containing compound is formed. In this state, a plasma state is caused by the arc, so that the water vapor and the halogen-containing compound are decomposed. Argon remains undecomposed. Due to the expansion at the time when the water is vaporized, the pressure in the arc chamber is increased, and plasma is ejected from the jet outlet at the tip of the arc chamber.
When ejected, the pressure of the arc chamber decreases, so that the injection pressure of mist and argon gas is superior, and argon gas and mist are supplied again, and the water particles are immediately vaporized by the heat of the arc chamber. This cycle time is determined by the diameter of the plasma outlet, the jet pressure, the diameter of the argon gas and mist inlets, the injection pressure, the heat capacity of the arc chamber, and the like. A groove is provided in a spiral shape on the wall surface of the outlet at the tip of the arc chamber. For this reason, the plasma surface advances while rotating, and is narrowed down. Recombination of hydrogen and oxygen is also generated, resulting in a high temperature state. According to experiments, the temperature is 6000 ° C-8000 ° C.
The organic substance melted in water is decomposed while the plasma is heated from the time when it is turned into plasma in the arc chamber. Argon gas is recovered and reused.
[0058]
On the other hand, when decomposing a halogen-containing compound gas that is difficult to melt into a liquid, argon gas is not used, but a liquid such as water is misted in the halogen-containing compound gas by the same method as described above, and this is converted into an arc chamber. The gas containing the water fine particles uniformly can be guided to the arc chamber. On the other hand, the tip of a pipe for injecting a gas containing mist into the arc chamber is narrowed down to obtain a jet power. In addition, by narrowing down, it is possible to prevent the explosive increase in the pressure in the arc chamber when the fine particles are vaporized and flow back to the mist carrying pipe, thereby reducing the efficiency of the water fine particle formation by the piezoelectric element. In the case of increasing the size of the apparatus, the injection pressure is injected by applying pressure by a pump for injection. The small one can use the force of the piezoelectric element that is used when misting as the power for injection. Injection may be continuous or intermittent, and generation of continuous or intermittent water plasma is possible, and the halogen-containing compound contained in water can be efficiently decomposed.
[0059]
The method of generating an arc is to either first contact the anode and cathode electrodes and separate them with current flowing, or to set the distance between the electrodes first and apply the electrical energy required for arc generation. Can be generated. The arc can be direct current or high frequency. In addition, by providing a plurality of arc chambers, by alternately generating arcs, continuous treatment is possible even when some arcs are stopped, and the efficiency of decomposition of halogen-containing compounds can be increased.
[0060]
In order to generate plasma using a halogen-containing compound and water as raw materials and to produce hydrogen efficiently by plasma reaction, the value of O / C, which is the ratio of oxygen to carbon in the plasma, must be 1.0 or more. desirable. This is because when this value is below 1.0, C is liberated and soot is generated.
[0061]
【Example】
EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.
Example 1
Trichloroethane was decomposed using water as a raw material. Trichloroethane is a colorless and transparent liquid, a volatile organochlorine compound having a solubility in water of 4400 mg / l and a boiling point of 74 ° C., and has an odor similar to chloroform. In addition, since trichloroethane is nonflammable, it is difficult to decompose by the combustion method used for chlorofluorocarbon decomposition.
Since trichloroethane is insoluble in water, water and trichloroethane were put in separate containers to generate a plasma consisting of a mixed vapor of water and trichloroethane. As a result of experiments, solid substances such as tar and soot were not generated downstream of the plasma. Sample the plasma gas downstream of the nozzle, and from the peak of the gas chromatograph, products containing C element are CO and CO₂Met. Further, trichloroethane was not detected, and decomposition was 100%.
[0062]
【The invention's effect】
As described above, as is clear from the detailed and specific explanation, according to the present invention, the halogen-containing compound and water are used as raw materials, the plasma is generated using the energy of the electrode generating the plasma, and the halogen-containing compound is decomposed. can do. The halogen-containing compound decomposition method according to the present invention is characterized in that it does not require a separate gas cylinder or a steam generator for containing a gas for generating plasma, and further does not require the insulation of the piping to prevent water vapor condensation. is there. Furthermore, it is possible to rapidly decompose the halogen-containing compound in an amount as required. Further, when it becomes necessary to stop the apparatus for some reason, it is possible to stop the apparatus safely and urgently by stopping the supply of power to the power source generating the water plasma. Since the entire apparatus is small and light, it is possible to carry the water plasma generator as needed. By vaporizing these halogen-containing compounds and water, it is possible to realize a method and apparatus for stably supplying the plasma into the plasma. In particular, the halogen-containing compounds and water are reacted efficiently, soot and waxy substances are generated by the plasma reaction. Thus, it is possible to realize a method and an apparatus for decomposing a halogen-containing compound efficiently, conveniently and rapidly without the production of. Therefore, the method and apparatus for decomposing halogen-containing compounds according to the present invention can quickly and efficiently decompose various halogen-containing compounds in which storage locations are scattered at a time and place as required. The industrial value of is extremely high.
[Brief description of the drawings]
[Figure 1]It is a schematic sectional drawing explaining the plasma mechanism in a plasma apparatus.
FIG. 2 shows an apparatus for carrying out the present invention.One specific exampleIt is sectional drawing of the schematic which shows these. This is an apparatus used when the organic compound is water-soluble.
3 is a cross-sectional view of a schematic diagram showing a detailed example of a main part of the apparatus shown in FIG. 2. FIG. This is an apparatus used when an organic compound is insoluble in water.
FIG. 4 is a schematic cross-sectional view showing a specific example of a conventional plasma apparatus.
[Explanation of symbols]
1 Torch body
2 Anode
3 Cathode holder
4Cathode
5 Container sleeve
6 Working fluid container
7 Moisture absorber
8 Porous thermal conductive material
9 links
10 Groove passage for passage
10a Groove passage
11 Discharge chamber
12 Electrically insulating tube
13 Thermally conductive tube
14 Lid
15 Spring
16 buttons
17 stopper
18 Working fluid replenishment hole
19 Plastic cover
20 Button flange
24 Organic compounds containing halogen and water
25 Container partition member
26 Organic compounds containing halogen and water storage chamber
27 Organic compounds containing halogen and water storage chamber
28 Piezo elements
29 Felt
30 heat resistant pipe
31 Countless spiral protrusions
32 Tangent groove passage
33 holes
34 holes

Claims (6)

A method of supplying a halogen-containing compound and water to an arc generated between a cathode and an anode, and decomposing the halogen-containing compound by the generated water plasma, wherein the halogen-containing compound and water are mist A method for decomposing a halogen-containing compound, characterized in that the thermal energy generated by direct current plasma applied to the cathode and the anode is vaporized by being conducted by a thermally conductive material and is supplied by the resulting excess pressure.   The method for decomposing a halogen-containing compound according to claim 1, wherein the mist formation is performed by an action of a diaphragm that vibrates at an ultrasonic frequency. The halogen-containing compound is CFC, halons, hydrofluorocarbons, decomposes hydrochlorofluorocarbons, trichloroethane, PCB, a halogen-containing compound according to claim 1 or 2, characterized in that a member selected from the group of SF ₆ Method.   To transmit heat generated by arc discharge, DC plasma torch composed of nozzle-like electrode and rod-like electrode, storage chamber for containing halogen-containing compound and water, mist chamber with vibration plate vibrating at ultrasonic frequency A halogen-containing compound decomposing apparatus by a plasma reaction method comprising the thermally conductive material and a container containing these and opening at the opening of the nozzle-like electrode, wherein the halogen-containing compound and water Mist is vaporized by the energy applied to the DC plasma torch, supplied to the discharge region generated by the DC plasma torch by the resulting excessive pressure, and the halogen-containing compound is decomposed by the generated water plasma. An apparatus for decomposing a halogen-containing compound by a plasma reaction method.   5. The halogen-containing compound according to claim 4, further comprising: a water-transmitting member disposed across both chambers for supplying the halogen-containing compound and water in the storage chamber to the mist chamber. Disassembly equipment. The halogen-containing compound is CFC, halons, hydrofluorocarbons, hydrochlorofluorocarbons, trichloroethane, PCB, the device for decomposing the halogen-containing compound according to claim 4 or 5, characterized in that a member selected from the group of SF ₆ .

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