JP2002126501A - Device for decomposing organic halogenated compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for decomposing an organic halogenated compound, in which the long life of a blowing pipe is realized. SOLUTION: In this device for decomposing the organic halogenated compound, thermal plasma is generated by irradiating to a gas containing the organic halogenated compound with a microwave and the same is decomposed in the thermal plasma. The device is equipped with both an exhaust gas treatment tank holding an alkali liquid and a blowing pipe 45 which is provided in such a state that an opened lower end part is immersed in the alkali liquid and blows decomposed gas of the organic halogenated compound into the alkali liquid. The blowing pipe 45 comprises a double pipe consisting of an inner tube 45a and an outer tube 45b and an air layer 46 is provided as a heat insulating layer between the inner tube 45a and the outer tube 45b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic halogen compound decomposing apparatus for decomposing an organic halogen compound such as chlorofluorocarbon.

[0002]

2. Description of the Related Art Organic halogen compounds such as chlorofluorocarbon (so-called chlorofluorocarbon) and trichloromethane containing fluorine, chlorine, bromine and the like in a molecule are widely used in a wide range of applications such as refrigerants, solvents and fire extinguishers. The importance in the industrial field is extremely high. However, these compounds have high volatility, and if released untreated into the atmosphere, soil, water, etc., they may produce carcinogens, destroy the ozone layer, etc.
Since it may adversely affect the environment, it is necessary to perform detoxification treatment from the viewpoint of environmental protection.

[0003] Conventionally, methods for treating organic halogen compounds have been reported which mainly utilize a thermal 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, the organic halogen compound is incinerated together with ordinary waste such as resin.On the other hand, in the plasma method, the organic halogen compound is reacted with water vapor in plasma to produce carbon dioxide, hydrogen chloride, and fluorine. It decomposes into hydrogen.

[0004] Further, as for the latter method of controlling the decomposition of an organic halogen compound according to the plasma method, a method of generating plasma using microwaves has recently been developed. The decomposition apparatus used in this decomposition method includes an exhaust gas treatment tank containing an alkaline solution, a reaction tube disposed with the open lower end immersed in the alkaline solution, and a vertically extending above the reaction tube. A cylindrical waveguide, a discharge tube disposed inside the cylindrical waveguide and penetrating the lower end thereof and communicating with the reaction tube, and extending horizontally and connected to the cylindrical waveguide near one end thereof. And a microwave oscillator mounted on the other end of the rectangular 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, acid gas (hydrogen fluoride and hydrogen chloride) is generated by this decomposition reaction.
This gas is guided into the alkaline liquid by the blowing pipe and neutralized, and the remaining gas including carbon dioxide gas is discharged from the exhaust duct.

[0006]

The acidic gas generated by the decomposition reaction of the chlorofluorocarbon gas exhibits severe corrosiveness. In the reaction tube, a considerable life can be expected by using a Ni-Cr alloy. However, in the blowing pipe that guides the acidic gas to the alkaline liquid, the acidic gas is condensed inside the blowing pipe due to the cooling by the alkaline liquid. Since the dew of an acidic gas is extremely corrosive compared to a gas, there is a problem that the life of the blow-in tube is extremely shortened.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an organic halogen compound decomposing apparatus which can prolong the life of a blowing pipe.

[0008]

According to the first aspect of the present invention, a thermal plasma is generated by applying microwave energy to a gas containing an organic halogen compound, and the organic halogen compound is decomposed in the thermal plasma. An exhaust gas treatment tank containing an alkaline solution, and a blowing pipe that is disposed with the open lower end immersed in the alkaline solution and blows a decomposition gas of an organic halogen compound into the alkaline solution. The blow pipe has a double pipe structure including an inner pipe and an outer pipe, and a heat insulating layer is provided between the inner pipe and the outer pipe.

In the present invention, since the heat insulating layer is provided between the inner pipe and the outer pipe of the blowing pipe, the temperature of the inner pipe is prevented from lowering to the dew point.

According to a second aspect of the present invention, in the organic halogen compound decomposing apparatus according to the first aspect, the blowing pipe has a straight pipe portion extending in a vertical direction, and a tip portion connected to a lower end of the straight pipe portion. Wherein the straight pipe portion has the double pipe structure, and the distal end portion is made of a material having corrosion resistance.

In the present invention, since the tip of the blowing pipe which is in direct contact with the alkaline liquid has corrosion resistance, even if the decomposition gas in the blowing pipe is dissolved in water to generate an acid solution, the blowing pipe is not corroded. Is prevented. Further, since the temperature of the decomposed gas decreases while passing through the straight pipe portion, the tip portion does not require high heat resistance.

According to a third aspect of the present invention, in the organic halogen compound decomposing apparatus according to the first or second aspect, the outer tube is extendable and contractible in a longitudinal direction.

The outer tube is at a low temperature in contact with the alkaline liquid, whereas the inner tube is exposed to a high-temperature decomposition gas and has a high temperature. Therefore, the expansion coefficient differs due to the difference in the coefficient of linear expansion between the inner pipe and the outer pipe. However, since the outer pipe can expand and contract as in the present invention, even if the inner pipe expands, its dimensional fluctuation is absorbed, and the inner pipe is expanded. No excessive stress occurs at the joint with the pipe.

[0014] The invention according to claim 4 is the invention according to claims 1 to 3.
In the organohalogen compound decomposer according to any of the above, while air is fed into the space between the inner tube and the outer tube as the heat insulating layer, the air is discharged from the space between the inner tube and the outer tube. It is characterized in that the combustion of the plasma is performed using air.

In the present invention, since air is sent between the inner pipe and the outer pipe, the heat insulating layer does not overheat. Also,
When the heat insulating layer is closed, water may enter due to expansion and contraction of the air in the heat insulating layer. However, since air is sent into the heat insulating layer from the outside, pressure fluctuation in the heat insulating layer can be prevented, and water intrusion can be prevented. Furthermore, since the introduced air is heated by the high-temperature plasma in the inner tube, when supplied to the discharge tube for use in burning the plasma, it prevents a local decrease in the discharge tube temperature in a portion where the air hits, Life can be extended.

[0016]

Next, an apparatus for decomposing an organic halogen compound according to the present invention will be described with reference to FIGS. In FIG. 1, a rectangular waveguide 1 extending in a horizontal direction is provided with a microwave oscillator 2 for oscillating a microwave having a frequency of 2.45 GHz at a starting end thereof, and transmits a microwave from a starting end to a terminating end. I do.

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 for moving a plurality of wave adjustment members 4 in and out of the discharge tube 5 so as to adjust the amount of wave mismatch of the wave and converge the wave to the discharge tube 5 are provided.

Here, the operation of generating microwaves will be described. The microwave oscillator 2 is placed at one end of a waveguide having a rectangular cross section, and drives a magnetron to emit an electromagnetic wave having a predetermined frequency. The characteristics of this electromagnetic wave propagation phenomenon can be grasped by solving Maxwell's wave equation relating to the electromagnetic wave. As a result, the electromagnetic wave propagates as an electromagnetic wave TE wave having no electric field component in the propagation direction.

[0019] indicated by arrows the direction examples of the first-order component TE ₁₀ alternates the propagation direction of the rectangular waveguide of Figure 2. The annular cavity of the double-cylindrical waveguide formed of a double-cylindrical conductor at the other end of the rectangular waveguide 1 has conductors 9 for electromagnetic waves propagating in the waveguide 1 and electromagnetic waves reflected at the tube end. , A TM wave having an electric field component in the traveling direction is generated in the annular cavity. The TM ₁₀ wave is the primary component are also shown by the arrows in the annular cavity of FIG. The fine adjustment caused by the second or higher harmonics related to the propagation of the electromagnetic wave is adjusted by the tuner 6. The isolator 3 prevents the microwave oscillator 2 from causing fundamental damage.

As shown in FIG. 2, the discharge tube 5 comprises an inner tube 11 and an outer tube 12, and is arranged so as to be coaxial with the central axis of the cylindrical waveguide 7. 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, and extends in the vertical direction near the terminal end of the rectangular waveguide 1 while communicating with the rectangular waveguide 1. Connected. The inner conductor 9 surrounds the quartz discharge tube 5 while being fixed to the upper part of the rectangular waveguide 1 and surrounds the outer conductor 8.
, And the extended portion is used as a probe antenna 9a. An ignition electrode 14 connected to an ignition transformer 13 is inserted into the inner tube 11 of the discharge tube 5. Further, the distal end (lower end) of the inner tube 11 is disposed at a predetermined distance inward from the distal end of the probe antenna 9a.

Now, as shown in FIG.
An optical sensor 17 is provided between the and the reaction tube 15 toward the exposed outer tube 12. The optical sensor 17 monitors the plasma generation state by detecting the luminous intensity.

As shown in FIG. 2, in a gap between the inner conductor 9 and the proximal end of the outer tube 12, a gas supply tube 16 is provided with an annular passage formed by the outer tube 12 and the inner tube 11. On the inlet side, they are inserted tangentially. Argon gas (rare gas), chlorofluorocarbon gas (organic halogen compound), air, and water vapor are supplied to the discharge tube 5 through the gas supply tube 16.
Is supplied to the annular passage. These argon gas, chlorofluorocarbon gas and air are supplied to the solenoid valves 19a and 19 shown in FIG.
By the opening / closing operation of b and 19c, it is selectively sent to the heater 18 from each supply source.

Argon gas is supplied to facilitate ignition prior to generation of plasma, and is stored in an argon cylinder 21. Needless to say, a rare gas such as helium or neon can be used in addition to the argon gas. A pressure regulator 22 and a pressure switch 23 are provided between the argon cylinder 21 and the solenoid valve 19a.
Is provided.

The air is supplied from the air compressor 24 in order to remove water remaining in the system to enhance the stability of ignition and to discharge gas remaining in the system. , Nitrogen gas, argon gas and the like are used. The water vapor is necessary for decomposing the chlorofluorocarbon gas, and is generated by sending water in the water storage tank 26 to the heater 18 by the plunger pump 25. This water storage tank 2
6 is provided with a level switch 27 for detecting a change in water level.

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 throttle device 31 is provided for quantifying the flow, and is constituted by, for example, a combination of a capillary tube and an orifice.

The mist separator 32 is for removing oil (lubricating oil) and water contained in the chlorofluorocarbon 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 water 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. Freon gas, argon gas, and air are introduced into one flow path 34a, and water is introduced from the water storage tank 26 into the other flow path 34b to generate steam. Channel 3 on the side that generates this water vapor
4b is filled with a resistor 35 that gives resistance to water vapor moving in the flow path 34b, so that the water vapor cannot flow smoothly in the flow path.

As the resistor 35, an inorganic or organic granular, fibrous, porous material or a molded product thereof is employed. From the viewpoint of preventing deterioration at high temperatures, SiO ₂ , Al, and the like are used. ₂ O ₃ , TiO ₂ , MgO, ZrO ₂
And inorganic materials such as oxides, carbides, nitrides and the like. A thermocouple 36 is provided near the outlet of the heater 18.

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.

The reaction tube 15 is provided with a blowing tube 45 via an exchange joint 44 as shown in FIG. The exchange joint 44 is detachably connected between the reaction tube 15 and the blowing tube 45. Here, the configuration of the blowing pipe 45 will be specifically described. As shown in FIG.
5a and an outer tube 45b. An air layer 46 as a heat insulating layer is provided between the inner tube 45a and the outer tube 45b. The blowing pipe 45 is composed of a straight pipe part 45c extending in the vertical direction and a tip part 45d continuous with the lower end of the straight pipe part 45c. The outer pipe 45b is formed only in the straight pipe part 45c, and the tip part 45d is formed. Is a part of the inner tube 45a, and extends substantially obliquely below the lower end of the outer tube 45b. The tip portion 45d is made of a material having corrosion resistance, specifically, a Ni-Cu alloy. The outer tube 45b is divided into an upper member 47a and a lower member 47b.
7b is connected by a bellows-like corrugated portion 47c formed of a soft material such as rubber. Thereby, the upper member 47a and the lower member 47b are
5 can be extended and contracted in the longitudinal direction. The corrugated portion 47c is provided at a position submerged in the alkaline liquid. The outer tube 45b has an opening 48a for introducing pressurized air into the air layer 46 and an opening 48b for discharging pressurized air from the air layer 46. The opening 48b on the discharge side is connected to the discharge tube 5, and the opening 48b
The air discharged from is discharged into the discharge tube 5.

The exhaust gas treatment tank 41 is provided to neutralize and detoxify the acidic gases (hydrogen fluoride and hydrogen chloride) generated when the fluorocarbon gas is decomposed and blown out from the blowing pipe 45. In addition, an alkaline suspension obtained by adding calcium hydroxide to water (hereinafter simply referred to as an alkaline solution) is contained. For example, when the Freon gas to be decomposed is Freon R12 for a refrigerant recovered from a waste refrigerator, the acidic gas generated by the decomposition reaction shown in Formula 1 is rendered harmless by the neutralization reaction shown in Formula 2.

(Equation 1) CCl ₂ F ₂ + 2H ₂ O → 2HCl + 2HF + CO ₂ (Equation 2) 2HCl + Ca (OH) ₂ → CaCl ₂ + 2H ₂ O 2HF + Ca (OH) ₂ → CaF ₂ + 2H ₂ O

The neutralized products (calcium chloride and calcium fluoride) produced by the neutralization reaction of the formula (2) have a low solubility, so that 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.

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 solution. Since the larger the contact area with the air and the longer the time until the air bubbles reach the liquid surface, the more the air is promoted, the air bubbles in the exhaust gas treatment tank 41 that accelerate the neutralization reaction of Formula 2 by finely dividing the air bubbles A dividing means 52 is provided.

The bubble dividing means 52 has six blades 52b driven to rotate by a motor 52a. The bubble separating means 52 is arranged so that the blade 52b is located above the tip of the blowing pipe 45, and the bubbles floating from the tip of the blowing pipe 45 hit the blade 52b rotating at about 300 rpm and have a diameter of about 3 mm to 5 mm. Finely divided into bubbles. 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. Bubble separating means 52
Keeps the operating state from the start of the operation of the plasma decomposition apparatus to the end of the operation. Except during the operation of the disassembly unit, it will be stopped.

Further, the exhaust gas treatment tank 41 has a pH value
A sensor 55 is provided. The pH value of the alkaline solution is
The control device 61 (see the overall configuration diagram in FIG. 3) constantly monitors the control device 61 via the pH sensor 55. For example, when the pH value becomes 9 (11 to 12 at the start of operation), the control device 6
The alarm means is actuated by the command from 1 and the disassembling operation is stopped. Any means can be used as the alarm means, as long as it can draw attention to the surroundings,
For example, means such as blinking a lamp or sounding a horn is employed.

Further, the exhaust gas treatment tank 41 is provided with a cooler 53 for cooling the alkaline liquid because the neutralization reaction of the formula 2 is an exothermic reaction. This cooler 53 is
A pump 53a for taking out the alkaline liquid from the bottom of the exhaust gas treatment tank 41, and a heat radiating section 53c through which the alkaline liquid passes and cooled by a fan 53b are provided. The alkaline liquid cooled by passing through the heat radiating portion 53c is:
It is returned to the exhaust gas treatment tank 41 again. Incidentally, the temperature in the tank is detected by the thermocouple 54.

Further, a three-way valve 56 is provided on the downstream side of the heat radiating section 53c. By switching the three-way valve 56, an alkaline solution containing a slurry as a processing liquid can be sent to the settling tank 62. Has become. A stirrer 62a is provided inside the settling tank 62, and after a coagulant is added to the treatment liquid to cause coagulation, solid-liquid separation is performed by a dehydrating basket 63 provided below the settling tank 62. ing.

A procedure for decomposing chlorofluorocarbon in the organic halogen compound decomposing apparatus having the above-described structure will be described. The opening and closing operation of the solenoid valve and the ignition operation of the ignition transformer 13 are controlled by the control device 61 as shown in FIG. As is clear from this figure, in this disassembly apparatus, 8
Decomposition of the chlorofluorocarbon gas is performed by batch processing with one cycle of time.

That is, before supplying the chlorofluorocarbon gas and water vapor, first, the operation of the decomposition apparatus is started by supplying the heated air for the purpose of removing the moisture remaining in the system for a predetermined time (3 minutes). I do. At this time, the operation of the bubble dividing means 52 also starts at the same time. After the air supply is stopped, the supply of argon gas is started for the purpose of improving ignition stability. Then, during the supply of the argon gas, the microwave is oscillated to ignite by the ignition transformer 13 and the steam and the chlorofluorocarbon gas are supplied to decompose the chlorofluorocarbon. Thereafter, the supply of the argon gas is stopped. The moisture may be removed by drying the air.

After the decomposition operation is stopped, air as scavenging gas is supplied for a predetermined time (5 hours) for the purpose of ensuring safety.
Min) and purge residual acid gases. The purged acid gas is neutralized in the exhaust gas treatment tank 41. At this time, by keeping the bubble separating means 52 in the operating state, the alkaline liquid is agitated and neutralization is promoted. Thereafter, the purging is stopped and the operation of the decomposition apparatus is terminated. At the same time, the motor 52a is stopped, and the operation of the bubble dividing means 52 is stopped. Since the stirring in the exhaust gas treatment tank 41 is stopped by the stop of the bubble dividing means 52, the slurry precipitates in the tank 41.

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. In particular, compared to other plasmas, for example, high frequency induction plasma, plasma by microwave is highly stable,
Even if the supply of the argon gas is stopped, there is almost no effect on the conversion of the chlorofluorocarbon gas into plasma.

The control device 61 includes the pressure switch 2
By receiving signals from various sensors such as 3, 33, thermocouples 36 and 54, the level switch 27, and the optical sensor 17, the supply pressure of argon gas and Freon gas to the heater 18, the liquid level in the water storage tank 26, the plasma Generation state,
The temperature in the exhaust gas treatment tank 41 is constantly monitored, and if these temperatures deviate from the prescribed values, the operation is stopped because there is a possibility that the operation is not performed normally or efficiently. After the operation is stopped, air is supplied as described above to ensure safety, and the residual gas in the device is scavenged.

Next, the chlorofluorocarbon decomposition step shown in FIG. 5 will be described in more detail. First, the solenoid valve 19a,
By closing the solenoid valve 19b and opening the solenoid valve 19c, the air from the air compressor 24 is supplied to the discharge tube 5 via the gas supply tube 16 for three minutes. This air is supplied to the heater 18.
Is heated to 100 to 180 ° C. For this reason, residual moisture in the device is reliably removed,
The ignition stability is improved.

Then, the solenoid valve 19c is closed and the solenoid valve 19a is opened to supply argon gas 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, stagnation is formed near the tip of the inner tube 11 and plasma is easily held.

The gas supply amount at this time is 4 to 40.
l / min, desirably 15 l / min or more. In this setting range, the stagnation is effectively formed, the plasma is more easily held, and the discharge tube 5 is hardly affected by the thermal influence of the plasma, so that melting deformation and breakage thereof are effectively prevented. Become.

Then, microwaves are oscillated from the microwave oscillator 2 at a constant 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 TM ₀₁ mode having a large electric field intensity is formed, and the electric field mode in the rectangular waveguide 1 and the electric field mode in the cylindrical waveguide 1 are formed by the inner conductor 9. The electric field inside the cylindrical waveguide 7 is stable because the electric field mode inside the cylindrical waveguide 7 is coupled. As a matter of course, the magnetic field is generated in a direction orthogonal to the electrolysis. The gas introduced into the discharge tube 5 is heated to a plasma state by the oscillating electromagnetic field.

Next, a high voltage is applied to the ignition electrode 14 connected to the ignition transformer 13 to generate a spark discharge between the ignition electrode 14 and the inner conductor 9 to ignite. At this time, the interior of the discharge tube 5 is easily ignited because the moisture is removed by air and an easily ignited argon gas is supplied in advance. Next, the water storage tank 2 is moved by the plunger pump 25.
Water is sucked from the heater 6, the water is sucked through the heater 18, and the generated steam is supplied to the discharge tube 5.

After the supply of water vapor is started, the supply of chlorofluorocarbon gas is started as described later. The reason for supplying the water vapor first is as follows. In the operation control method of the organic halogen compound decomposer according to the present embodiment, the fluorocarbon gas and water vapor are supplied at a constant molar ratio to decompose and react,
Generates acidic gas. This is because if only the fluorocarbon gas is turned into plasma, an unexpected harmful halogen compound is generated due to recombination of the dissociated atoms, so that the detoxification process cannot be performed. Therefore, as described above, by supplying steam to the discharge tube 5 and then supplying chlorofluorocarbon gas, and maintaining the state where water vapor is present at the time of chlorofluorocarbon decomposition,
CFCs can be safely decomposed.

The steam cannot flow smoothly in 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 or 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.

The steam, argon gas, and CFC gas flowing into the mixer 37 through the heater 18 flow out in a uniformly mixed state, and are supplied to the discharge tube 5. For this reason, the decomposition reaction of Formula 1 is sufficiently performed, and the generation of by-products such as chlorine gas and carbon monoxide can be suppressed.

When the CFC gas supplied to the discharge tube 5 is irradiated with the microwave, the discharge tube 5
High electron energy and temperature of 2,000K ~
Thermal plasma increased to 6,000 K is generated. At this time, not only the chlorofluorocarbon gas and water vapor but also the discharge tube 5
Since the argon gas is supplied at the same time, the plasma does not disappear.

Further, since the distal end of the inner tube 11 is disposed at a predetermined distance inward from the distal end of the probe antenna 9a, the thermal influence of the generated plasma can be avoided.
Melt breakage of the inner tube 11 is prevented. 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 atoms, fluorine atoms, and hydrogen atoms, so that it 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. Therefore, when the fluorocarbon gas is decomposed for a long time, the supply of argon is unnecessary, and the consumption of argon can be kept low. The gas produced by the decomposition reaction passes through the exchange joint 44 and the blowing pipe 45,
It is released into the alkaline liquid in 1.

Thus, the product gas released into the alkaline solution through the blowing pipe 45 is rendered harmless by the neutralization reaction of the formula (2). Since the neutralization reaction is an exothermic reaction, the temperature of the alkaline solution is maintained at about 60 ° C. or lower by the cooler 53.

The generated 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 discharged out of the system due to insufficient neutralization.

Since the air pipe 46 is provided in the blowing pipe 45, the inner pipe 45a is not cooled by the alkaline liquid, and the formation of dew inside the inner pipe 45a is prevented. Therefore, corrosion of the inner tube 45a due to dew condensation can be prevented. Since the temperature of the decomposed gas decreases as it passes through the inner pipe 45a, the temperature of the decomposed gas at the tip 45d is lower than that of the straight pipe 45c. On the other hand, the decomposition gas exhibits severe corrosiveness when dissolved in an alkaline solution.
Since a Ni-Cu alloy is used for the tip 45d, the tip 45d exhibits corrosion resistance to this corrosive property,
To achieve a longer life. In addition, the conventional blow tube is made of Ni-Cr.
Since Cr is not eluted as compared with the case where it is formed of a system alloy, the drainage treatment can be simplified.

A corrugated portion 47c is formed on the outer tube 45b. Therefore, even if the inner tube 45a becomes hot and expands, the outer tube 45b extends in the longitudinal direction in accordance with the dimensional fluctuation of the inner tube 45a. Therefore, the outer tube 45b and the inner tube 45
It is prevented that an excessive stress is generated at a joint portion with a and the joint is broken. Since the corrugated portion 47c is always immersed in the alkaline liquid, it is cooled. Therefore, high heat resistance is not required.

Pressurized air is supplied to a space (air layer 46) between the inner tube 45a and the outer tube 45b. If the air layer 46 is closed, water may enter the air layer 46 due to expansion and contraction of air due to temperature fluctuation. However, since the air in the air layer 46 is pressurized air whose pressure has been adjusted, the pressure does not fluctuate, and water intrusion can be prevented. Furthermore, when air at room temperature is supplied to the discharge tube 5, the temperature of the portion of the discharge tube 5 that is exposed to the air locally decreases, and the life of the discharge tube 5 is reduced. In this example, since the air in the air layer 46 heated by the plasma in the inner tube 45a is guided to the discharge tube 5 and used for combustion of the plasma, the temperature of the discharge tube 5 where the air hits is prevented from lowering. Life can be extended. Also, even if the gas in the inner tube 45a leaks to the air layer 46, it is guided to the discharge tube 5 together with the pressurized air.

Now, of the product gas detoxified by the neutralization reaction, gas is exhausted from the exhaust duct 42, and the other gas remains as slurry in the alkaline liquid. After the decomposition operation is stopped, the processing liquid is pumped up by the pump 53a after stopping the bubble separating means 52, and the three-way valve 56 is switched to be transferred to the settling tank 62. The processing liquid transferred to the sedimentation tank 62 is
After the coagulant is uniformly added while stirring at a, the stirrer 62a is stopped to cause sedimentation, then solid-liquid separated in the dehydrating basket 63, the liquid component is treated as waste water, and the solid component is discarded.
After the decomposition operation is stopped, the air compressor 24 is driven to scavenge the acid gas remaining in the apparatus, so that the safety is also improved.

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) The outer tube 45b is provided with the corrugated portion 47c. However, as shown in FIG. 6, the outer tube 45b 'is divided into upper and lower portions and the O-ring 50 is sandwiched therebetween, so that the longitudinal direction of the outer tube 45b' is It may be formed to be stretchable. (2) As shown in FIG. 7, a blowing pipe 145 including an inner pipe 145a and an outer pipe 145b having a double pipe structure up to the tip may be used. (3) Instead of pH control of alkaline solution, as a means to avoid the discharge of acidic gas outside the system due to insufficient neutralization treatment,
The motor current value may be managed. That is,
When the motor speed decreases or stops, the air bubbles discharged from the blowing pipe 45 may not be sufficiently divided, and the neutralization reaction may not be sufficiently performed. Therefore, if the abnormality of the motor rotation is detected based on the motor current value and the operation of the decomposing device is stopped by a command from the control device 61, the discharge of the acid gas out of the system can be prevented beforehand.

(2) Instead of disposing the tip of the ignition electrode 14 inside the discharge tube 5, it may be arranged outside the discharge tube 5 to ignite by spark discharge. (3) The distance at which the tip of the inner tube 11 separates inward from the tip of the probe antenna 9a is set to be equal to the distance between the tip of the probe antenna 9a and the energy concentration portion due to microwaves unless the inner tube 11 is melted. Is best,
It may be appropriately changed in consideration of the melting of the inner tube 11.

(4) The bubble dividing means 52 may be of a screw type in which a propeller is fixed to the tip of a shaft. (5) The neutralizing solution stored in the exhaust gas treatment tank 41 is not limited to the above-mentioned alkaline suspension, and an alkaline aqueous solution such as a sodium hydroxide aqueous solution may be used.

[0066]

As described above, according to the organic halogen compound decomposing apparatus of the present invention, the following effects can be obtained. According to the first aspect of the present invention, since the heat-insulating layer is formed on the blow-in tube, the occurrence of dew condensation inside the inner tube is prevented. Therefore, corrosion of the inner tube due to dew condensation can be prevented. According to the second aspect of the present invention, since a material having corrosion resistance is used at the tip of the blow pipe, it exhibits corrosion resistance against severe corrosiveness caused by the decomposition gas being dissolved in water. To extend the life of the part.

According to the third aspect of the present invention, since the outer tube is formed to be expandable and contractable, even if the inner tube expands due to a high temperature, the outer tube is elongated in accordance with the dimensional change of the inner tube. Stretch in the direction. Therefore, it is possible to prevent the connection between the outer tube and the inner tube from being damaged due to excessive stress generated at the joint.

According to the fourth aspect of the invention, pressurized air is supplied to the space between the inner pipe and the outer pipe. If the air layer is closed, the air will expand and expand due to temperature fluctuations.
Water may enter the air layer due to contraction. However, since the air in the air layer is pressurized air whose pressure is adjusted, it is possible to prevent water from entering. Furthermore, since the air in the air layer heated by the plasma in the inner tube is guided to the discharge tube and used for burning the plasma, the temperature of the discharge tube in a portion where the air hits can be prevented from lowering, and the life of the discharge tube can be extended.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an organic halogen compound decomposing apparatus according to the present invention.

FIG. 2 is a sectional view showing a discharge tube and a reaction tube of the decomposition apparatus.

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

FIG. 4 is an enlarged view showing a blowing pipe of the decomposition apparatus.

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

FIG. 6 is an enlarged view of a blowing pipe shown as a modification.

FIG. 7 is an enlarged view of a blowing pipe shown as a modification.

[Explanation of symbols]

 41 Exhaust gas treatment tank 45 Blowing pipe 45a Inner pipe 45b Outer pipe 45c Straight pipe part 45d Tip part 46 Air layer (heat insulation layer)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masahiro Bessho 1 Takamichi, Iwazuka-cho, Nakamura-ku, Nagoya-shi, Aichi Prefecture Inside Nagoya Research Laboratory, Mitsubishi Heavy Industries, Ltd. No. 1 Takamichi, Nagoya Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Yuji Okada 3-1-1, Asahimachi, Nishi-Biwajima-cho, Nishi-Kasugai-gun, Aichi Prefecture, Japan Inside the Cooling Business Division of Mitsubishi Heavy Industries, Ltd. 60 Ikutsu-cho, Iwazuka-cho, Nakamura-ku, Ichino-cho F-term (reference) in Nakanishi Engineering Co., Ltd. 2E191 BA12 BA15 BD18 4G075 AA37 BA01 BA05 CA26 CA48 DA01 EB27 FB02 FC06 FC09 4H006 AA04 AA05 AC13 AC26 BA95

Claims (4)

[Claims] 1. An apparatus for generating thermal plasma by applying microwave energy to a gas containing an organic halogen compound and decomposing the organic halogen compound in the thermal plasma, wherein an exhaust gas treatment containing an alkaline liquid is performed. A tank, and a blow-off pipe arranged with the open lower end immersed in the alkaline liquid, and blowing a decomposition gas of an organic halogen compound into the alkaline liquid, wherein the blow-in pipe has an inner pipe and an outer pipe. Is a double-pipe structure,
An organic halogen compound decomposing apparatus, wherein a heat insulating layer is provided between the inner tube and the outer tube. 2. The apparatus for decomposing an organic halogen compound according to claim 1, wherein the blow pipe comprises a straight pipe portion extending in a vertical direction, and a tip end portion connected to a lower end of the straight pipe portion. An apparatus for decomposing an organic halogen compound, wherein a pipe portion has the double-tube structure, and the tip portion is made of a material having corrosion resistance. 3. The organic halogen compound decomposer according to claim 1, wherein the outer tube is capable of extending and contracting in a longitudinal direction. 4. The organic halogen compound decomposing apparatus according to claim 1, wherein air is sent into a space between the inner tube and the outer tube as the heat insulating layer, and the inner tube and the outer tube are separated from each other. An apparatus for decomposing an organic halogen compound, wherein the combustion of the plasma is performed using air exhausted from a space between the tube and the tube.