JP2000331795A - Microwave plasma torch and decomposing device for organic halogen compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave plasma torch which enables stable operation by maintaining a satisfactory plasma shape after it is ignited, while having satisfactory ignition performance when starting the operation, and a decomposing device for an organic halogen compound. SOLUTION: This microwave plasma torch is equipped with a cylindrical wave guide 7 comprising an outside conductor 8 and an inside conductor 9, and a discharge tube 5 having a double structure comprising an internal tube 11 coaxially installed in the cylindrical wave guide 7 and an external tube 12, a probe antenna 9a formed by extending the inside conductor 9 is disposed so as to surround the discharge tube 5, and the tip of the internal tube 11 is positioned so as to be positioned inside of the tip of the probe antenna 9b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for decomposing an organic halogen compound using plasma, and more particularly, to an apparatus for decomposing an organic halogen compound using microwaves to generate plasma, and this decomposition apparatus. The present invention relates to a microwave type plasma torch suitable for use in the present invention.

[0002]

2. Description of the Related Art Organic halogen compounds such as freon, trichloromethane, and halon containing fluorine, chlorine, and bromine in a molecule are widely used in a wide range of applications such as refrigerants, solvents, and fire extinguishers. Is very important.
However, these compounds have high volatility, and if released untreated into the environment such as air, soil, and water, they may have adverse effects on the environment, such as formation of carcinogenic substances and destruction of the ozone layer. It is necessary to perform detoxification treatment from the viewpoint of environmental protection.

[0003] Conventionally, there have been reported methods for treating organic halogen compounds, which mainly utilize a decomposition reaction at a high temperature, and this treatment method is further roughly classified into an incineration method and a plasma method. In the incineration method, an organic halogen compound is incinerated in a cement kiln or rotary kiln, whereas in the plasma method, an organic halogen compound is reacted with water vapor in plasma to be decomposed into carbon dioxide, hydrogen chloride, and hydrogen fluoride. Things.

Further, there is an apparatus for decomposing an organic halogen compound according to the latter plasma method, which generates plasma using microwaves. This disassembly device
An exhaust gas treatment tank containing an alkaline solution, a reaction tube disposed with the open lower end immersed in the alkaline solution, a cylindrical waveguide extending vertically above the reaction tube, and the cylinder A discharge tube disposed inside the waveguide and penetrating the lower end thereof and communicating with the reaction tube; a rectangular waveguide extending in the horizontal direction and connected to the cylindrical waveguide near one end thereof; It has a microwave oscillator and the like mounted on the other end of the waveguide.

[0005] In this decomposition apparatus, while the Freon gas and the water vapor are supplied to the discharge tube, the microwave oscillated from the microwave oscillator is transmitted to the cylindrical waveguide through the rectangular waveguide. Then, a discharge is caused by the microwave electric field formed inside the cylindrical waveguide, and the fluorocarbon gas is decomposed by the thermal plasma in the reaction tube. On the other hand, the generated gas generated by this decomposition reaction is neutralized by passing through an alkaline solution, and the remaining gas including carbon dioxide gas is discharged from the exhaust duct.

[0006]

By the way, in the above-mentioned apparatus for decomposing an organic halogen compound according to the plasma method, reliable and stable ignition of gas at the start of operation is required. During the operation of the apparatus after the ignition is completed, it is important to maintain a favorable plasma shape and continue a stable decomposition reaction.

The present invention has been made in view of the above circumstances, and has as its object to have good ignition performance at the start of operation, and to maintain a stable and stable plasma shape after ignition. An object of the present invention is to provide a microwave type plasma torch and an organic halogen compound decomposing device which enable operation.

[0008]

Means for Solving the Problems In order to solve the above problems, the present invention employs the following constitution. Claim 1
The described microwave plasma torch includes a cylindrical waveguide composed of an outer conductor and an inner conductor, and a discharge tube having a double structure composed of an inner tube and an outer tube coaxially installed in the cylindrical waveguide. A probe antenna formed by extending the inner conductor is disposed so as to surround the discharge tube, and the tip of the inner tube is positioned inside the tip of the probe antenna.

According to such a microwave-type plasma torch, the gas flow flowing spirally between the inner tube and the outer tube and flowing out forms stagnation just below the inner tube. Therefore, it is possible to easily ignite the stagnation of the gas flow.
In addition, since the tip of the inner tube is located inside the tip of the probe antenna, the tip of the inner tube is separated from the energy concentration portion of the plasma and is less affected by heat.

According to a second aspect of the present invention, there is provided an apparatus for decomposing an organic halogen compound, wherein an exhaust gas processing tank containing a processing solution for neutralizing the decomposed product of the organic halogen compound is provided, and an open lower end is provided in the exhaust gas processing tank. A reaction tube disposed in a state of being immersed in the processing solution, a cylindrical waveguide formed of an outer conductor and an inner conductor extending vertically above the reaction tube, and installed coaxially in the cylindrical waveguide. A discharge tube having a double structure comprising an inner tube and an outer tube, wherein a probe antenna formed by extending the inner conductor is arranged so as to surround the discharge tube, and a tip of the inner tube is formed by the probe antenna. And a microwave-type plasma torch positioned inside the tip of the microwave plasma torch.

According to such an apparatus for decomposing an organic halogen compound, a reliable and stable ignition performance at the start of operation and a stable decomposition reaction can be maintained by maintaining a good plasma shape during operation.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In FIG. 3, the rectangular waveguide 1 extending in the horizontal direction is provided with a microwave oscillator 2 that oscillates a microwave having a frequency of 2.45 GHz at the start end (left end), and from the start end to the end (right end). To transmit microwaves.

As shown in FIG. 1, the rectangular waveguide 1 prevents the reflected wave from affecting the oscillation side by absorbing the microwave reflected at the terminal end and returning to the start end. An isolator 3 and a tuner 6 that adjusts the wave mismatch amount of the radio wave by moving a plurality of wave adjustment members 4 in and out respectively to converge the radio wave to the discharge tube 5 are provided.

As shown in FIG. 2A, the cylindrical waveguide 7 is composed of an outer conductor 8 and an inner conductor 9 having a smaller diameter than the outer conductor 8. They are connected so as to extend in the vertical direction while communicating with the waveguide 1. The inner conductor 9 extends toward the end plate 8A of the outer conductor 8 while surrounding the discharge tube 5 made of quartz while being fixed on the upper portion of the rectangular waveguide 1, and this extended portion is used as a probe antenna 9a. I have.

The discharge tube 5 has a double structure composed of an inner tube 11 and an outer tube 12, and a gas flow path is provided between the inner tube 11 and the outer tube 12. Such a double-tube discharge tube 5 is disposed inside so as to be coaxial with the central axis of the cylindrical waveguide 7. Hereinafter, in the present invention, a combination of the cylindrical waveguide 7 and the discharge tube 5 is referred to as a microwave plasma torch (or simply, a plasma torch). A Tesla coil 14 that generates heat by an ignition device 13 is inserted into the inner tube 11 of the discharge tube 5.

Further, the tip (lower end) of the inner tube 11 extends a predetermined distance L inward (upward) from the tip of the probe antenna 9a that extends the inner conductor 7 downward and surrounds the discharge tube 5. It is located at the retracted position (Fig. 2
(B)). This distance L is given by:
It is best to set the tip of the probe antenna 9a and the tip of the inner tube 11 to coincide, that is, set L = 0. However, when L = 0 is set, the inner tube 1
Since the front end of the first member is exposed to the energy concentration portion of the plasma, continuation of the operation causes melting deformation due to the heat effect. If the tip of the inner tube 11 is melted and deformed, the flow of gas flowing out between the inner tube 11 and the outer tube 12 becomes unstable, and the plasma shape is significantly deformed. Therefore, the decomposition reaction may become unstable, or the outer tube 12 may be damaged by the thermal influence of the deformed plasma.

However, in the present invention, since the tip of the inner tube 11 is raised and the distance L is provided between the tip of the probe antenna 9a as described above, the tip of the inner tube 11 is It is not affected by heat away from the central part. In addition, as the distance L is increased, the effect on the heat effect is further improved. However, the distance for forming the swirling flow of the gas is shortened accordingly, so that the heat effect and the swirling flow are limited in the limited space. It is necessary to consider a proper balance with the formation. The tip of the inner tube 11 is connected to the probe antenna 9a.
If it extends downward from the tip of the electrode, it is unfavorable because the thermal effect of the plasma is greatly affected.

On the other hand, the tip of the outer tube 12 penetrates through the end plate 8A of the outer conductor 8 and communicates with the copper reaction tube 15;
The proximal end (upper end) of the outer tube 12 is attached with a gap between the outer tube 12 and the inner conductor 9. Reference numeral 17 denotes an optical sensor 17 directed to the outer cylinder 12 exposed between the end plate 8A of the outer conductor 8 and the reaction tube 15. This optical sensor 1
Numeral 7 monitors the state of plasma generation by detecting the luminous intensity.

A gas supply pipe 16 is inserted into the gap along the tangential direction of the outer pipe 12, and argon gas,
Freon gas (organic halogen compound), air, and water vapor are supplied to the discharge tube 5 via the gas supply tube 16. These argon gas, chlorofluorocarbon gas, and air are selectively sent to the heater 18 from respective supply sources by opening and closing operations of the solenoid valves 19a, 19b, and 19c shown in FIG.

The argon gas is supplied to facilitate ignition prior to generation of plasma, and is stored in an argon cylinder 21. This argon cylinder 21
A pressure regulator 22 and a pressure switch 23 are provided between the solenoid valve 19a and the solenoid valve 19a.

Air is supplied from the air compressor 24 to remove water remaining in the system to enhance ignition stability and to exhaust gas remaining in the system. , Nitrogen gas, argon gas and the like are used. Water vapor is necessary to decompose Freon gas.
It is generated by sending water in the water storage tank 26 to the heater 18 by the plunger pump 25. The water storage tank 26 has a level switch 27 for detecting a change in water level.
Is provided.

The Freon gas is stored in a liquid in a collected Freon cylinder 28, and the collected Freon cylinder 28 and the electromagnetic valve 1 are stored.
9b, the squeezing device 31, the mist separator 3
2, and a pressure switch 33 are provided.

The mist separator 32 is for removing oil (lubricating oil) and water contained in the CFC gas, and is of a collision type or a centrifugal type. The heater 18 is intended not only to generate water vapor to be reacted with the chlorofluorocarbon gas, but also to prevent the problem that the vapor is cooled down to the chlorofluorocarbon gas and re-condensed in the apparatus by heating the fluorocarbon gas or the like in advance. A heating method such as an electric type or a steam type is adopted.

In the heater 18, two parallel flow paths 3 are provided.
4a and 34b are formed, and Freon gas, argon gas, and air are introduced into one flow path 34a,
Water is introduced into the other flow path 34b from the water storage tank 26 to generate steam.

However, the fluorocarbon gas and the like having passed through the heater 18 and the water vapor are mixed in the mixer 37 and then supplied to the discharge tube 5 through the gas supply tube 16. As shown in FIG. 4, an orifice 38 is provided inside the mixer 37, and an opening 38a of the orifice 38 is set to a diameter of 0.1 mm to 5 mm. The outlet-side end surface 37A of the mixer 37 facing the opening 38a has an inclined surface such that the cross section of the flow path gradually decreases.

The exhaust gas treatment tank 41 is provided to neutralize and detoxify acidic gases (hydrogen fluoride and hydrogen chloride) generated when the fluorocarbon gas is decomposed. Is contained therein. For example, if the decomposed Freon gas is Freon R12 for a refrigerant recovered from a waste refrigerator, the following formula 1 is used.
The generated gas generated by the decomposition reaction shown in the above is detoxified by the neutralization reaction shown in the equation (2).

[0027]

[Formula 1] CCl ₂ F ₂ + 2H ₂ O → 2HCl + 2HF + CO ₂

[Formula 2] 2HCl + Ca (OH) ₂ → CaCl ₂ + 2H ₂ O 2HF + Ca (OH) ₂ → CaF ₂ + 2H ₂ O

Since the neutralized products (calcium chloride and calcium fluoride) produced by the neutralization reaction of the formula (2) have low solubility, some of them are dissolved in an alkaline solution, but most of them are present as a slurry. Further, the carbon dioxide generated by the decomposition reaction of the formula 1 and the acid gas reduced to a very small amount equal to or less than the emission reference value by the neutralization reaction of the formula 2 are connected to the exhaust duct 42 connected above the exhaust gas treatment tank 41. Is discharged out of the system by the blower 43.

Inside the exhaust gas treatment tank 41, a blowing pipe 45 connected to the reaction pipe 15 via an exchange joint 44 is provided.
It is arranged to extend vertically with its lower end immersed in an alkaline solution. The tip 4 of this blowing pipe 45
5a is formed so as to be inclined at a predetermined angle with respect to the vertical direction.

A cooler 46 provided with a cold water pipe (not shown) is provided at an intermediate portion in the axial direction of the reaction tube 15 so as to surround the peripheral surface thereof. The cooler 46 cools a gas produced by the decomposition reaction of the formula 1, and the reaction tube 1
In order to prevent the re-condensation of the residual water vapor in 5, it is controlled not to cool below the dew point. In the present embodiment, the cooling is performed to about 400 ° C.

The cooling water (warm water) of the cooler 46, which is heated by cooling the reaction tube 15, is used as a heating source of the recovered CFC cylinder 28. That is, a heater 4 provided with a hot water pipe (not shown) is provided around the recovered CFC cylinder 28.
7 is provided, and when the cooling water used for cooling the reaction tube 15 flows through the hot water pipe, the recovered CFC cylinder 28 is heated.

As shown in FIG. 2, the exchange joint 44 is detachably connected between the reaction tube 15 and the blowing tube 45, and the water injection nozzle 51 communicates with the inside thereof. Cooling water is discharged from the water injection nozzle 51, and the resin-made, for example, Teflon-made blowing pipe 45 is rapidly cooled to its heat-resistant temperature range. Incidentally, when the blowing pipe 45 is a Teflon pipe, it is cooled to 100 ° C. or lower.

The reason why the blowing pipe 45 is made of resin is that the blowing pipe 45 has good corrosion resistance to both an acid solution formed by dissolving an acidic gas in cooling water and an alkali solution in the exhaust gas treatment tank 41. This is because it is difficult to achieve this with a metal. On the other hand, in the case of the reaction tube 15,
Since the inside is always in a dry state, there is little possibility that the acidic gas generated by the decomposition reaction of the formula 1 is dissolved in water and is corroded by an acidic liquid. On the other hand, heat resistance to high-temperature plasma and decomposed gas is required.

From the tip (lower end) of the blowing pipe 45, the gas produced by the decomposition reaction of the formula 1 is released as bubbles into the alkaline liquid. The neutralization reaction in the alkaline solution is accelerated as the contact area between the bubbles and the alkaline solution increases and the time until the bubbles reach the liquid surface is increased. A bubble dividing means 52 for promoting the neutralization reaction of Formula 2 by dividing is provided.

The bubble separating means 52 includes a shaft 52b rotated by a motor 52a, a disk-shaped blade holder 52c fixed to the end of the shaft 52b, and an outer edge of the blade holder 52c. And six blades 52d.

The shaft portion 52a and the blade holding portion 52
Each of c and the blade 52d is made of a SUS material, and the blade 52d intersects the blade holding portion 52c and is fixed by silver brazing at equal intervals in the circumferential direction. The reason why the silver brazing is employed is that the general welding is highly corrosive to an alkaline solution.

The bubble separating means 52 includes a blade holder 52
The center of c is arranged so as to be located above the tip of the reaction tube 15, and the air bubbles that float from the tip of the reaction tube 15 are:
When the blade 52d rotates at 300 rpm, it is finely divided into bubbles having a diameter of about 3 to 5 mm. The bubble separating means 52 also plays a role of forming a suspension of water and water-insoluble calcium hydroxide by stirring the calcium hydroxide powder charged into the exhaust gas treatment tank 41.

Further, the exhaust gas treatment tank 41 is provided with a cooler 53 for cooling the temperature in the tank below the heat resistant temperature of the blow-in pipe 45 because the neutralization reaction of the formula 2 is an exothermic reaction. In the cooler 53, a part of a pipe connected to a heat radiating part 53b cooled by a fan 53a is inserted through the exhaust gas treatment tank 41, and a cooling medium such as water flows through the pipe to generate heat. And the heat dissipating part 53
Heat is dissipated in b. Incidentally, the temperature in the tank is detected by the thermocouple 54.

Further, the exhaust gas treatment tank 41 has a pH value
A sensor 55 is provided. The pH value of the alkaline solution is
It is constantly monitored by the control device 61 via the pH sensor 55. For example, when the pH value is 9 (11 to 11 when the operation is started).
In the case of 12), the alarm means is activated by a command from the control device 61, and the disassembling operation is stopped. As the warning means, any means can be used as long as it can draw attention to the surroundings. For example, means such as blinking a lamp or sounding a horn is adopted.

Since the slurry in the exhaust gas treatment tank 41 gradually increases as the operation time elapses, the slurry is received by the solid-liquid separator 62 together with the alkali liquid after the operation is stopped.
After solid-liquid separation, it is disposed of as waste or used for other purposes. On the other hand, the separated alkaline liquid is returned to the exhaust gas treatment tank 41 again and reused. Incidentally, the fluctuation of the liquid level in the exhaust gas treatment tank is detected by the level switch 56.

In the organic halogen compound decomposing apparatus having the above-described structure, the opening / closing operation of the electromagnetic valve and the ignition operation of the Tesla coil 14 are controlled by the control device 61 as shown in FIG. As is clear from this figure, in this decomposition apparatus, the decomposition of the chlorofluorocarbon gas is performed by batch processing in which one cycle is performed for 8 hours.

That is, before supplying the chlorofluorocarbon gas or water vapor, first, air is supplied for a predetermined time (3 minutes) for the purpose of removing residual moisture, and after the supply is stopped, argon gas is supplied for the purpose of improving ignition stability. Start supplying. Then, during the supply of the argon gas, the microwave is oscillated to ignite the gas by the Tesla coil 14, and the steam and the chlorofluorocarbon gas are supplied. Thereafter, the supply of the argon gas is stopped.

After the decomposition operation is stopped, air is supplied for a predetermined time (5 minutes) for the purpose of ensuring safety, and residual acid gas is purged.

In the above steps, the supply of the argon gas and the supply of the chlorofluorocarbon gas may overlap with each other. However, the time between the start of the supply of the chlorofluorocarbon gas and the stop of the supply of the argon gas may be very small. The reason is,
This is because, as long as the ignition state is stabilized, it is not necessary to continuously supply the argon gas, and it is necessary to keep the argon consumption low from the viewpoint of cost reduction.

The control device 61 is provided with the pressure switch 2
3, 33, thermocouples 36, 54, level switches 27, 5
6. By receiving signals from various sensors such as the optical sensor 17, the heaters 18 for the argon gas and the chlorofluorocarbon gas are used.
Supply pressure, the liquid level in the water storage tank 26, the state of plasma generation, the temperature and the liquid level in the exhaust gas treatment tank 41 are constantly monitored. Stop operation because there is a possibility that the operation is not performed efficiently. After the operation is stopped, air is supplied as described above to ensure safety, and the residual gas in the apparatus is scavenged.

Hereinafter, the operation of the disassembling apparatus according to this embodiment will be described. In this disassembly apparatus, first, the solenoid valve 19
a, 19b are closed and the solenoid valve 19c is opened to supply air from the air compressor 24 to the discharge tube 5 via the gas supply tube 16 for 3 minutes. This air is passed through the heater 18 to produce 100 to 180
Since it is heated to ° C., the residual moisture in the apparatus is surely removed.

Next, the solenoid valve 19c is closed and the solenoid valve 19a is opened, and argon gas is supplied to the discharge tube 5. At this time, since the argon gas is supplied from the tangential direction of the outer tube 12 and flows down spirally in the discharge tube 5 having the double structure, stagnation is formed near the tip of the inner tube 11 to facilitate ignition. In addition, it is easy to hold the plasma after ignition.

The gas supply amount at this time is 4 to 40.
l / min, preferably 12 l / min or more. In this setting range, stagnation is effectively formed, and ignitability and retention of plasma are further facilitated. Further, since an appropriate distance L is provided between the tip of the inner tube 11 and the tip of the probe antenna 9a, the discharge tube 5 is hardly affected by the thermal influence of the plasma, and its melting deformation and breakage are effectively prevented. Will be.

Then, microwaves are oscillated from the microwave oscillator 2 at a certain interval from the start of the supply of the argon gas. The microwave is transmitted to the rear end side by the rectangular waveguide 1 and further transmitted to the cylindrical waveguide 7.

At this time, as the electric field in the cylindrical waveguide 7, a TM01 mode having a large electric field intensity is formed, and the electric field mode in the rectangular waveguide 1 and the cylindrical waveguide 7 Since the electric field modes inside the cylindrical waveguide 7 are coupled, the electric field inside the cylindrical waveguide 7 is stable.

Next, the Tesla coil 1 is
4 is heated to ignite. At this time, the interior of the discharge tube 5 is easily ignited because moisture is removed by air and an easily ignited argon gas is supplied in advance. Next, water is sucked from the water storage tank 26 by the plunger pump 25, and the water is drawn through the heater 18 to supply the generated steam to the discharge tube 5.

The steam cannot flow smoothly through the flow path due to the resistor 35 filled in the heater 18, and a constant amount of steam always stays in the heater 18. For this reason, scattering due to pulsation and bumping is prevented, the outflow amount of steam is stabilized, and fluctuations in the flow rate on the upstream side of the mixer 37 can be effectively suppressed. Therefore, the plasma can be stabilized without causing the disappearance of the plasma, and the processing capability can be improved.

Next, the solenoid valve 19b is opened to supply Freon gas to the discharge tube 5. At this time, the chlorofluorocarbon gas flowing out of the collected chlorofluorocarbon cylinder 28 is supplied to the mist separator 3.
2 to remove oil and moisture.
For this reason, the generation of dirt and by-products from piping and the like due to the lubricating oil in the CFC gas is suppressed, and an efficient and stable supply of CFC gas and the like can be performed. Does not occur. Therefore, it is possible to stabilize the plasma and improve the processing capability.

Further, after passing through the heater 18, the mixer 37
The water vapor, the argon gas, and the chlorofluorocarbon gas flowing into the inside not only promote mixing due to the pressure loss when passing through the opening 38 a of the orifice 38, but also form the outlet side end face 3.
Mixing is also promoted by colliding with 7A,
The mixture flows out of the mixer 37 in a more uniformly mixed state, and is supplied to the discharge tube 5. Therefore, Equation 1
Is sufficiently performed, and the generation of by-products such as chlorine gas and carbon monoxide can be suppressed.

When the microwave is applied to the Freon gas supplied to the discharge tube 5 in this manner, the discharge tube 5
High electron energy and temperature of 2,000K ~
Thermal plasma increased to 6,000 K is generated.

Further, since the distal end of the inner tube 11 is disposed inside the distal end of the probe antenna 9a by a predetermined distance L, it is possible to avoid the thermal influence of the generated plasma, and Is prevented from being melted. As a result, a stable decomposition operation can be performed without remarkable deformation of the plasma shape.

However, the generation of thermal plasma causes the fluorocarbon gas to be easily dissociated into chlorine, fluorine, and hydrogen atoms, and is easily decomposed by reacting with water vapor as shown in equation 1. When the plasma is stabilized, the electromagnetic valve 19a is closed to stop the supply of the argon gas.

The gas generated by the decomposition reaction is supplied to the exchange joint 44.
Then, the gas is discharged into the alkaline liquid in the exhaust gas treatment tank 41 through the blowing pipe 45. However, since these generated gases are extremely high in temperature, they are first cooled to about 400 ° C. by the cooler 46 attached to the lower part of the reaction tube 15 before flowing into the blowing tube 45.

At this temperature, the residual water vapor does not re-condense inside the reaction tube 15, so that the reaction tube 15 is kept in a dry state and the plasma does not disappear. On the other hand, the cooling water of the cooler 46 heated to about 50 ° C. by cooling the reaction tube 15 is led to the heater 47 attached to the recovered freon cylinder 28, and the liquid freon in the recovered freon cylinder 28 is vaporized. In addition to preventing the formation of frost in the cylinder 28 and the downstream pipe that occurs when the pressure is reduced, the pressure fluctuation due to the temperature drop is also suppressed.

The product gas cooled by the cooler 46 is
While passing through the exchange joint 44, the water injection nozzle 51
Is rapidly cooled to about 100 ° C. or less by the cooling water discharged from the apparatus. Thereby, the resin blowing tube 45 can be used within its heat-resistant temperature range, and can be protected from thermal damage due to high temperature.

At this time, since the gas produced by the decomposition reaction of the formula (1) is dissolved in the cooling water to generate an acidic solution, the exchange joint 44 is gradually corroded. It can be replaced accordingly. That is, on the downstream side of the reaction tube 15, only the exchange joint 44 needs to be exchanged due to corrosion, so that the cost can be reduced and the exchange operation can be facilitated.

The product gas released into the alkaline solution through the blowing pipe 45 is rendered harmless by the neutralization reaction of the formula 2, and is discharged from the exhaust duct 42. Since this neutralization reaction is an exothermic reaction, the temperature of the alkaline solution is set to 70 ° C. by the cooler 53 in order to prevent thermal damage to the blowing pipe 45.
It is kept below.

The product gas released as bubbles from the tip of the blowing pipe 45 is supplied to the blade 52 of the bubble dividing means 52.
Since it is finely divided at d, the contact area with the alkaline liquid increases and the time to reach the liquid surface increases, thereby promoting the neutralization reaction. As a result, the amount of acidic gas exceeding the reference value is not continuously discharged out of the system due to insufficient neutralization.

The neutralized product produced by the neutralization reaction is
Although present as a slurry in the alkaline liquid, the slurry is received by the solid-liquid separator 62 together with the alkaline liquid after the decomposition operation is stopped, and is continuously subjected to solid-liquid separation. Since the separated liquid is returned to the exhaust gas treatment tank 41 and reused, in the present decomposition apparatus, the water consumption is significantly reduced in combination with the reuse of the cooling water.

The apparatus for decomposing an organic halogen compound according to the present invention is not limited to the above embodiment, but includes the following embodiments. (1) As means for promoting the mixing in the mixer 37, beads or the like may be filled in the mixer 37 instead of the orifice 38. In this configuration, the mixing of the flon gas and the steam is promoted because the gas randomly flows through the gap formed in the mixer 37.

Further, a plurality of baffles may be provided on the inner peripheral surface of the mixer 37, for example, alternately vertically or horizontally at intervals (static mixer). In this configuration, the mixing of the flon gas and the water vapor is promoted since the gas flows in a meandering manner.

Further, the pipe connected to the inlet side of the mixer 37 may be inclined with respect to the flow direction, and a guide plate extending spirally may be provided on the inner peripheral surface of the mixer 37 (swirl mixer). . In this configuration, since the CFC gas and the steam flow while drawing a spiral, mixing is promoted.

(2) Since the slurry in the exhaust gas treatment tank 41 is settled if left overnight after the operation is stopped, the settled high-concentration slurry is pumped up, and the slurry is separated into solid and liquid for disposal. It may be. In this case, since only the high-concentration slurry can be pumped without mixing with the free alkali solution, efficient slurry treatment can be performed. In addition, if a granulating agent, a coagulant, or the like is added to the alkaline solution to increase the number of slurry particles, the sedimentation time can be reduced, and the slurry treatment can be performed more efficiently.

(3) Connect the tip of the Tesla coil 14 to the discharge tube 5
May be arranged outside the discharge tube 5 to ignite by spark discharge. (4) Instead of heating the collected CFC cylinder 28 to make it into a gas state and allowing the CFC gas to flow out, instead of inverting the collection CFC cylinder 28 and allowing the collected CFC gas to flow out in a liquid state, a throttling device such as a differential pressure control valve , The flow may be quantified, heated and vaporized, and sent to the heater 18 side. In this case, by heating the expansion device and the piping, the flow rate fluctuation due to the temperature drop is suppressed.

(5) To heat the recovered CFC cylinder 28,
Instead of the cooling water used for cooling the reaction tube 15, the cooling water of the cooler 53 used for cooling the slurry in the exhaust gas treatment tank 41 may be used. (6) The distance L at which the tip of the inner tube 11 is separated inward from the tip of the probe antenna 9a is equal to the tip of the probe antenna 9a if the inner tube 11 has no problem of melting (that is, the distance L).
L = 0) is optimal.

(7) The bubble dividing means 52 may be of a screw type in which a propeller is fixed to the tip of a shaft. In addition, the bubble dividing means 52 includes each component 52b,
52c and 52d may be made of resin such as Teflon, and these may be screw-connected. In this configuration, there is no welding portion, and each component 52b, 52c,
Since 52d is made of resin, it has extremely excellent corrosion resistance.

(8) Instead of inclining the distal end of the blowing pipe 45 at a predetermined angle with respect to the vertical direction, the blowing pipe 45 may be formed in a substantially U-shape. (9) The neutralizing solution stored in the exhaust gas treatment tank 41 is not limited to the above-described alkaline suspension, and an alkaline aqueous solution such as an aqueous sodium hydroxide solution may be used.

[0073]

As is apparent from the above description, the present invention has the following effects. (A) According to the microwave plasma torch of the first aspect, the stagnation of the gas flow occurs at the lower portion of the inner tube by employing the discharge tube having the double structure, and the ignitability is improved by igniting the stagnation. Therefore, reliable and stable ignition becomes possible. Further, since the distance L is provided between the distal end of the inner tube and the distal end of the probe antenna, and the inner tube is positioned inside, the distal end of the inner tube is separated from the energy concentration portion of the plasma and is less likely to be affected by heat. Therefore, it is possible to prevent the inner tube from being thermally deformed, and it is possible to continue a stable decomposition reaction by supplying a stable gas flow.

(B) The apparatus for decomposing an organic halogen compound according to the second aspect employs a plasma torch which is excellent in ignitability and can continue a stable decomposition reaction. Ignition is performed, and a stable decomposition reaction can be continuously performed during operation.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of a decomposition apparatus according to the present invention.

FIG. 2A is an enlarged view of a main part of the decomposition apparatus, and FIG. 2B is an explanatory view showing an outline of a microwave type plasma torch part.

FIG. 3 is a perspective view showing an entire configuration of the disassembling apparatus.

FIG. 4 is a sectional view of a main part of a mixer provided in the decomposition apparatus.

FIG. 5 is a comparative diagram showing the time when microwaves, argon gas, and the like are supplied and the time of ignition in the decomposition apparatus over time.

[Explanation of symbols]

 Reference Signs List 5 discharge tube 7 cylindrical waveguide 8 outer conductor 9 inner conductor 9a probe antenna 11 inner tube 12 outer tube 15 reaction tube 41 exhaust gas treatment tank 61 control device (control means)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshio Hattori 1 Fukumita, Nagoya Laboratory, Iwazuka-cho, Nakamura-ku, Nagoya-shi, Aichi F-term (reference) 2E191 BA12 BB00 BD18 4G075 AA37 AA65 BA05 BB04 CA02 CA15 CA26 CA47 CA62 CA63 EB21 EB27 EB43

Claims (2)

[Claims] An inner conductor comprising: a cylindrical waveguide comprising an outer conductor and an inner conductor; and a discharge tube having a double structure comprising an inner tube and an outer tube coaxially provided in the cylindrical waveguide. A microwave type plasma torch characterized in that a probe antenna obtained by extending the above is disposed so as to surround the discharge tube, and the tip of the inner tube is located inside the tip of the probe antenna. 2. An exhaust gas treatment tank containing a treatment liquid for neutralizing a decomposition product of an organic halogen compound, and an open lower end portion is disposed in a state immersed in the treatment liquid in the exhaust gas treatment tank. A reaction tube, a cylindrical waveguide formed of an outer conductor and an inner conductor extending vertically above the reaction tube, and a double tube formed of an inner tube and an outer tube coaxially installed in the cylindrical waveguide. A microwave antenna having a discharge tube having a structure, wherein a probe antenna formed by extending the inner conductor is arranged to surround the discharge tube, and the tip of the inner tube is positioned inside the tip of the probe antenna. An apparatus for decomposing an organic halogen compound, comprising: a plasma torch.