JP3448270B2 - Organic halogen compound decomposition equipment - Google Patents

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 organic halogen compounds such as CFCs, and more particularly to a technique for improving the durability of a reaction tube.

[0002]

2. Description of the Related Art Organohalogen compounds such as chlorofluorocarbons (so-called CFCs) and trichloromethane containing fluorine, chlorine, bromine, etc. in their molecules are widely used in a wide range of applications such as refrigerants, solvents, fire extinguishing agents , The importance in the industrial field is extremely high. However, these compounds are highly volatile, and if they are left untreated and released into the environment such as the atmosphere, soil, and water, the formation of carcinogenic substances, destruction of the ozone layer, etc.
Since it may adversely affect the environment, it is necessary to detoxify it from the viewpoint of environmental protection.

Conventionally, as a method for treating an organic halogen compound, there has been reported one mainly utilizing a thermal decomposition reaction at a high temperature, and this treating method is roughly classified into an incineration method and a plasma method. In the incineration method, an organic halogen compound is incinerated together with ordinary waste such as a resin, whereas in the plasma method, the organic halogen compound is reacted with water vapor in plasma to generate carbon dioxide, hydrogen chloride, and fluorine. It decomposes into hydrogen fluoride.

Further, as the operation control method of the latter organic halogen compound decomposing apparatus according to the plasma method, a method of generating plasma using microwaves has been developed in recent years. The decomposition apparatus used in this decomposition method includes an exhaust gas treatment tank containing an alkaline liquid, a reaction tube disposed with the opened lower end portion immersed in the alkaline liquid, and a vertical extension above the reaction tube. An existing cylindrical waveguide, a discharge tube disposed inside the cylindrical waveguide and penetrating the lower end thereof to communicate with the reaction tube, and extending horizontally and connected to the cylindrical waveguide in the vicinity of one end thereof. And a microwave transmitter attached to the other end of the rectangular waveguide.

In this decomposition apparatus, while the Freon gas and water vapor are supplied to the discharge tube, the microwave emitted from the microwave oscillator is transmitted to the cylindrical waveguide through the rectangular waveguide. Then, electric discharge is caused by the microwave electric field formed inside the cylindrical waveguide, and CFC gas is decomposed by thermal plasma in the reaction tube. On the other hand, this decomposition reaction produces acidic gas (hydrogen fluoride and hydrogen chloride) and carbon monoxide. Of these, carbon monoxide cannot be discharged as it is, so secondary air is mixed into the reaction tube and converted into carbon dioxide by a combustion reaction. Then, the acid gas is introduced into the alkaline liquid by the blowing pipe to be neutralized, and the remaining gas containing carbon dioxide and the like is discharged from the exhaust duct.

[0006]

By the way, in the apparatus for decomposing an organohalogen compound according to the above plasma method,
As described in the prior art, the decomposed gas generated in the reaction tube contains hydrogen fluoride, an acidic gas of hydrogen chloride, and carbon monoxide. Of these, carbon monoxide cannot be discharged to the outside as it is. Therefore, it is necessary to mix secondary air into the reaction tube to cause a combustion reaction to form carbon dioxide and then discharge the carbon dioxide. Since such a combustion reaction process is performed, the temperature of the reaction tube becomes considerably high, and since it contains corrosive gases such as hydrogen fluoride and hydrogen chloride, it exhibits extremely high corrosiveness. Therefore, in order to further improve the practicability of the apparatus for decomposing organic halogen compounds, it is an important subject to suppress the corrosion of the reaction tube to increase the durability and improve the frequent inspection and replacement of parts.

In order to suppress such corrosion of the reaction tube,
For example, there is a conventional technique in which a heat shield plate is provided around the reaction tube, or the reaction tube is water-cooled as described in JP-A-9-148096. However, the above-mentioned installation of the shielding plate does not positively cool the reaction tube, so that the environment of high temperature, which is one of the factors that promotes corrosion, cannot be sufficiently improved. Further, in the conventional technique of cooling the reaction tube with water, it is necessary to supply pressurized water in order to keep the cooling temperature at the dew point temperature or higher, and therefore, difficult problems such as pressure resistance design and watertight design arise. It is not preferable to cool the reaction tube below the dew point temperature because there is a problem of rapid wall thinning due to liquid corrosion.

The present invention has been made in view of the above circumstances, and provides an apparatus for decomposing an organohalogen compound, which suppresses corrosion of a reaction tube by easily cooling it to a temperature equal to or higher than the dew point temperature and improves its practicality. The purpose is to do.

[0009]

In order to solve the above problems, the present invention adopts the following configurations. Claim 1
The apparatus for decomposing an organic halogen compound according to claim 1, comprises a reaction tube for decomposing the organic halogen compound, an exhaust gas treatment tank containing an alkaline solution for neutralizing the decomposition products decomposed in the reaction tube, and an open lower end. In a decomposition apparatus for an organohalogen compound, which is arranged in a state of being immersed in the alkaline liquid and comprises a blowing pipe for blowing the decomposition product into the alkaline liquid from the reaction pipe, a cooling chamber is formed around the reaction pipe. It is characterized in that air is circulated in the cooling chamber to cool it to a temperature above the dew point temperature.

According to such an organic halogen compound decomposing apparatus, it is possible to cool the reaction tube in a corrosive environment where it is exposed to acid gas at high temperature to a temperature above the dew point temperature by air. The progress of corrosion can be suppressed and the life of the reaction tube can be extended. The reason why the cooling temperature is set to the dew point temperature (140 ° C.) or higher is to avoid the liquid corrosion.

In the apparatus for decomposing an organohalogen compound according to claim 1, the cooling temperature of the reaction tube is from 200 ° C to
It is preferably 300 ° C. This is because it is difficult to maintain the cooling temperature above the dew point temperature at 200 ° C. or lower, and the corrosion suppression effect is reduced at 300 ° C. or higher.

Further, in the apparatus for decomposing an organic halogen compound according to claim 1 or 2, it is preferable that the cooling chamber is configured to be divisible so that the cooling chamber provided around the reaction tube is divided. Since it can be easily attached and detached, not only can the cooling chamber be reused, but also maintenance and replacement work of the reaction tube can be facilitated.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an apparatus for decomposing an organic halogen compound according to the present invention will be described with reference to FIGS. 1 to 4. In FIG. 1, a rectangular waveguide 1 extending in the horizontal direction is provided with a microwave oscillator 2 for transmitting a microwave having a frequency of 2.45 GHz at the start end thereof, and the microwave is transmitted from the start end side to the end side. To transmit.

As shown in FIG. 1, the rectangular waveguide 1 absorbs the microwave reflected at the terminal end side and returned to the starting end side to prevent the reflected wave from affecting the transmitting side. There is provided an isolator 3 and a tuner 6 that adjusts the amount of wave-like mismatch of radio waves by entering and exiting the plurality of wave adjusting members 4 to converge the radio waves on the discharge tube 5.

The microwave generation operation will be described below. The microwave transmitter 2 is placed at one end of a waveguide having a rectangular cross section to drive a magnetron and radiate an electromagnetic wave of a predetermined frequency. The characteristic of this electromagnetic wave propagation phenomenon can be understood by solving Maxwell's wave equation relating to the electromagnetic wave, but as a result, it propagates as an electromagnetic wave TE wave having no electric field component in the propagation direction.

An example of this first-order component TE10 is shown by alternating arrows in the propagation direction of the rectangular waveguide of FIG. In addition, an electromagnetic wave propagating through the waveguide 1 is provided in the annular cavity of the double cylindrical waveguide formed of a double cylindrical conductor at the other end of the rectangular waveguide 1.
By the coupling action of the conductor 9 of the electromagnetic wave reflected at the pipe end,
A TM wave having an electric field component in the traveling direction is generated in the annular cavity. The TM10 wave, which is the first-order component, is also indicated by an arrow in the annular cavity of FIG. The tuner 6 makes fine adjustments due to the second and higher harmonics involved in the propagation of electromagnetic waves. The isolator 3 prevents the microwave oscillator 2 from being fundamentally damaged.

Now, as shown in FIG. 2, the discharge tube 5 is composed of 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 diameter smaller than that of the outer conductor 8, and extends in the vertical direction in a state of communicating with the rectangular waveguide 1 in the vicinity of the end of the rectangular waveguide 1. Are connected as. The inner conductor 9 surrounds the quartz discharge tube 5 while being fixed to the upper portion of the rectangular waveguide 1, and the outer conductor 8
Of the probe antenna 9a. Further, an ignition electrode 14 connected to an ignition transformer 13 is inserted in the inner tube 11 of the discharge tube 5.

Further, the tip (lower end) of the inner tube 11 is arranged inward by a predetermined distance from the tip of the probe antenna 9a.

On the other hand, the tip of the outer tube 12 penetrates the end plate 8A of the outer conductor 8 to communicate with the reaction tube 15, and the outer tube 1
The base end side (upper end side) of 2 is attached with a gap between it and the inner conductor 9. End plate 8A of outer conductor 8
An optical sensor 17 is provided between the reaction tube 15 and the reaction tube 15 toward the exposed outer cylinder 12. The optical sensor 17 monitors the plasma generation state by detecting the luminous intensity.

In the gap between the inner conductor 9 and the base end side of the outer cylinder 12, a gas supply pipe 16 is tangentially provided on the inlet side of the annular passage formed by the outer pipe 12 and the inner pipe 11. Are inserted along. Argon gas (rare gas), Freon gas (organic halogen compound), air, and water vapor are supplied to the annular passage of the discharge tube 5 via the gas supply pipe 16. These argon gas, CFC gas, and air are
By opening / closing operations of the solenoid valves 19a, 19b, 19c shown in FIG. 1, the respective supply sources are selectively sent to the heater 18.

Argon gas is supplied to facilitate ignition prior to plasma generation, and is stored in the 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 the water remaining in the system to improve the stability of ignition and to discharge the gas remaining in the system. , Nitrogen gas, argon gas, etc. are used. The water vapor is necessary for decomposing the fluorocarbon gas, and is generated by sending the water in the water storage tank 26 to the heater 18 by the plunger pump 25. This water tank 2
6 is provided with a level switch 27 for detecting a change in water level.

The chlorofluorocarbon gas is stored in the recovered chlorofluorocarbon cylinder 28 as a liquid, and the recovered chlorofluorocarbon cylinder 28 and the solenoid valve 1 are stored.
9b, the expansion device 31, the mist separator 3
2 and a pressure switch 33 are provided. The expansion device 31 is provided for the purpose of quantifying the flow, and is composed of, 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 fluorocarbon gas, and is of a collision type or a centrifugal type. The heater 18 is intended not only to generate steam that reacts with CFC gas, but also to avoid the problem that steam is cooled to CFC gas and recondensed in the apparatus by preheating CFC gas and the like. The heating method such as electric type and steam type is adopted.

Inside the heater 18, two flow paths 3 are arranged in parallel.
4a and 34b are formed, and the freon gas, the argon gas, and the air are introduced into one flow path 34a, and the water is introduced from the water storage tank 26 into the other flow path 34b to generate steam. Flow path 3 on the side that generates this water vapor
4b is filled with a resistor 35 that gives resistance to the water vapor moving in the flow path 34b, so that the water vapor cannot smoothly flow in the flow path.

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

However, the CFC gas and the steam having passed through the heater 18 are mixed in the mixer 37 and then supplied to the discharge tube 5 through the gas supply tube 16.

A cooling chamber 70 is formed around the reaction tube 15 so as to surround the outer peripheral surface. In the cooling chamber 70, the cooling air is circulated inside so that the reaction tube 1
5 is cooled to a temperature above the dew point temperature (140 ° C.). That is, the cooling chamber 70 is connected to the blower 80 provided as a supply source of the cooling air by a pipe, and is placed inside the cooling chamber while controlling the temperature so as not to overcool the reaction tube 15 until it becomes lower than the dew point temperature. The reaction tube 15 is configured to be cooled from the outer peripheral side by circulating air.

A suitable cooling temperature is not lower than the dew point temperature in order to prevent dew condensation in the reaction tube 15, but a more preferable cooling temperature is higher than the dew point temperature of 140 ° C. 20
It is in the range of 0 ° C to 300 ° C. That is, if the cooling temperature is lower than 200 ° C., it is difficult to control the temperature control such that the cooling temperature is too close to the dew point temperature to maintain the dew point temperature or higher.
If the cooling temperature is higher than 00 ° C., the intended effect of lowering the temperature and suppressing corrosion will be reduced. In addition, in order to manage and control the cooling temperature described above, a temperature detecting sensor (not shown) may be installed in an appropriate place in the cooling chamber 70, and the operation of the blower 80 may be controlled according to the temperature detected by the sensor.

Further, the cooling chamber 70 described above is provided, for example, in FIG.
As shown in, in order to be easily attached and detached on the outer peripheral side of the reaction tube 15, it has a structure that can be divided into left and right. In the example of the divided structure shown in FIG. 5, the right case 71R and the left case 71L, which are formed by dividing a prism into two and have a U-shaped cross section, are provided with screws 72.
Are fastened together at multiple locations with the right upper plate 73R and the flange surfaces provided on the upper and lower surfaces, respectively.
Left upper plate 73L and right lower plate 74
R, left lower plate 74L with screws, cooling chamber 7
A space covering 0 is formed outside the reaction tube 15. Then, the right upper plate 73R, the left upper plate 73L and the right lower plate 74R,
The left lower plate 74L is provided with a semicircular cutout so as to be in close contact with the outer peripheral surface of the reaction tube 15. In addition,
The division structure of the cooling chamber 70 is not limited to this, and various modifications that can be divided at the outer peripheral portion of the reaction tube 15 are possible.

Further, reference numeral 75 in the drawing is an inlet opening for cooling air, and 76 is an outlet opening, and a flange (not shown) of a pipe connecting the inlet opening 75 and a blower 80 via a gasket 77. And a hood 78 for discharging cooled air to the atmosphere is attached to the outlet opening 76. With such a structure, the cooling chamber 70 and the pipes connected to the cooling chamber 70 can be easily disassembled and attached and detached while the reaction tube 15 is left as it is. It can be used repeatedly even once. In addition, inside the cooling chamber 70, that is, the right case 7
It is preferable to provide an appropriate air guide plate (not shown) on the inner surfaces of the 1R and the left case 71L so that the cooling air that has flowed in from the inlet opening 75 does not flow out directly from the outlet opening 76. The working air swirls around the outer peripheral surface of the reaction tube 15 and can cool the entire surface of the reaction tube 15 evenly. It is also possible to improve the cooling efficiency by providing fins on the outer surface of the reaction tube 15 or in the cooling chamber 70 to increase the contact area with the cooling air.

Further, as shown in FIG. 2, the reaction tube 15 is provided with a blowing tube 45 via an exchange joint 44. The exchange joint 44 is detachably connected between the reaction tube 15 and the blow tube 45.

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

(Equation 1) CCl2F2 + 2H2O → 2HCl + 2HF + CO2 (Formula 2) 2HCl + Ca (OH) 2 → CaCl2 + 2H2O 2HF + Ca (OH) 2 → CaF2 + 2H2O

Since the neutralized products (calcium chloride and calcium fluoride) produced by the neutralization reaction of the formula 2 have a low solubility, some of them are dissolved in the alkaline solution, but most of them exist as a slurry. Further, the carbon dioxide produced 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 exhaust duct 42 connected above the exhaust gas treatment tank 41. Is discharged from the system by the blower 43.

From the tip (lower end) of the blow pipe 45, the gas produced by the decomposition reaction of the formula 1 is released as bubbles in the alkaline liquid. Since the larger the contact area with the bubble and the longer it takes for the bubbles to reach the liquid surface, the bubbles are promoted in the exhaust gas treatment tank 41 by finely dividing the bubbles to promote the neutralization reaction of Formula 2. A dividing means 52 is provided.

The bubble cutting means 52 is provided with six blades 52b which are rotationally driven by a motor 52a. The bubble dividing means 52 is arranged such that the blade 52b is located above the tip of the blow tube 45, and the bubbles floating from the tip of the blow tube 45 hit the blade 52b rotating at about 300 rpm and have a diameter of about 3 mm to 5 mm. It is divided into small bubbles. Further, the bubble dividing means 52 also plays a role of producing a suspension of water-insoluble calcium hydroxide and water by stirring the calcium hydroxide powder put into the exhaust gas treatment tank 41. The bubble dividing means 52 keeps the operating state from the start of operation of the plasma decomposition apparatus to the end of operation thereof. Keep it in a stopped state except during the operating period of the disassembling device.

Further, the exhaust gas treatment tank 41 has a pH value of
A sensor 55 is provided. The pH value of alkaline solution is
It is constantly monitored by the control device 61 (see FIG. 3) via the pH sensor 55. For example, when the pH value becomes 9 (11 to 12 at the start of operation), the alarm means is activated by a command from the control device 61. At the same time, the disassembly operation is stopped. As the alarm means, any means can be used as long as it can draw attention to the surroundings, and for example, a means such as blinking a lamp or smoothing a horn is adopted.

Further, since the neutralization reaction of the equation 2 is an exothermic reaction, the exhaust gas treatment tank 41 is provided with a cooler 53 for cooling the alkaline liquid. This cooler 53
The exhaust gas processing tank 41 is provided with a pump 53a for taking out the alkaline liquid from the bottom, and a heat radiating portion 53c through which the alkaline liquid passes and is cooled by a fan 53b. The alkaline liquid cooled by passing through the heat dissipation portion 53c is
It is returned to the exhaust gas treatment tank 41 again. By the way, the temperature inside the tank is detected by the thermocouple 54.

Further, a three-way valve 56 is provided on the downstream side of the heat radiating portion 53c, and by switching the three-way valve 56, an alkaline liquid containing 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 so that a coagulant is added to the treatment liquid to cause coagulation and then solid-liquid separation is performed by a dehydrating basket 63 provided below the settling tank 62. ing.

A procedure for decomposing fluorocarbons in the decomposition apparatus for an organic halogen compound having the above structure will be described. The opening / 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 can be seen from this figure, this decomposition device
Freon gas is decomposed by batch processing in which the time is one cycle.

That is, before supplying CFC gas or water vapor, first, the air heated for the purpose of removing the water remaining in the system is supplied for a predetermined time (3 minutes) to start the operation of the decomposition apparatus. To do. At this time, the operation of the bubble dividing means 52 is also started at the same time. After the air supply is stopped, the supply of argon gas is started to improve the ignition stability. Then, while the argon gas is being supplied, microwaves are emitted to ignite by the ignition transformer 13, and steam and chlorofluorocarbon are supplied to decompose chlorofluorocarbon. Then, the supply of argon gas is stopped. The water may be removed by drying the air.

After the disassembling operation is stopped, air as scavenging gas is kept for a predetermined time (5
Min) is supplied and residual acid gas is purged. The purged acidic gas is neutralized in the exhaust gas treatment tank 41. At this time, by keeping the bubble dividing means 52 in an operating state, the alkaline liquid is stirred and neutralization is promoted. Then, the purging is stopped and the operation of the decomposition apparatus is completed. At the same time, the motor 52a is stopped and the operation of the bubble cutting means 52 is stopped. Since the stirring in the exhaust gas treatment tank 41 is stopped by stopping the bubble dividing means 52, the slurry is precipitated in the tank 41.

In the above steps, the supply of the argon gas and the supply of the freon gas may overlap each other, but the time from the start of the supply of the freon gas to the stop of the supply of the argon gas may be very small. The reason is,
This is because it is not necessary to continue supplying the argon gas as long as the ignition state is stable, and it is necessary to keep the argon consumption low from the viewpoint of cost reduction. In particular, microwave plasma is more stable than other plasmas such as high frequency induction plasma,
Even if the supply of the argon gas is stopped, there is almost no effect on the plasma conversion of the CFC gas.

Further, the control device 61 includes the pressure switch 2
By receiving signals from various sensors such as 3, 33, thermocouples 36, 54, level switch 27, and 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 The generation state of
The temperature inside the exhaust gas treatment tank 41 is constantly monitored, and if these deviate from the specified values, the operation may be stopped normally or efficiently, so the operation is stopped. Then, after the operation is stopped, air is supplied as described above to ensure safety, and residual gas in the device is scavenged.

Next, regarding the CFC decomposition apparatus of the present invention,
The action will be described in more detail based on the process of CFC decomposition. First, the electromagnetic valves 19a and 19b are closed and the electromagnetic valve 19c is opened to supply the air from the air compressor 24 to the discharge tube 5 through the gas supply tube 16 for 3 minutes. This air passes through the heater 18,
It is heated to 100 to 180 ° C. For this reason, the residual moisture in the device is surely removed, and the stability of ignition is improved.

Then, the electromagnetic valve 19c is closed and the electromagnetic 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 in a spiral shape, stagnation is formed near the tip of the inner tube 11 and the plasma is easily retained.

The gas supply amount at this time is 4 to 40.
l / min, preferably 15 l / min or more. In this setting range, stagnation is effectively formed, plasma is more easily retained, and the discharge tube 5 is less susceptible to the thermal influence of plasma, and its melt deformation and damage are effectively prevented. Become.

Then, a microwave is transmitted from the microwave transmitter 2 at a constant interval from the start of supplying the argon gas. The microwave is transmitted to the rear end side of the rectangular waveguide 1 and further to the cylindrical waveguide 7.

At this time, as the electric field in the cylindrical waveguide 7, the TM01 mode having a large electric field strength is formed, and the inner conductor 9 causes the electric field mode in the rectangular waveguide 1 and the cylindrical waveguide 7 to be generated. Since the internal electric field mode is coupled, the electric field in the cylindrical waveguide 7 is stable. Naturally, the magnetic field is generated in the direction orthogonal to the electrolysis. The gas introduced into the discharge tube 5 is heated to a plasma state by the vibrating 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 itself and the inner conductor 9 to ignite it. At this time, the interior of the discharge tube 5 is easily ignited because the moisture is removed by air and the argon gas which is easy to ignite is supplied in advance. Next, the water tank 2 is driven by the plunger pump 25.
Water is sucked from 6 and passed through the heater 18 to supply the generated steam to the discharge tube 5.

After the supply of steam is started, the supply of CFC gas is started as described later. The reason for supplying steam first is as follows. In the method for controlling the operation of the decomposition apparatus for an organohalogen compound according to the present embodiment, CFCs and water vapor are supplied at a constant molar ratio for decomposition and reaction,
Generates acid gas. This is because if only the Freon gas is turned into plasma, unexpectedly harmful halogen compounds are generated due to recombination of dissociated atoms, and the harmless treatment cannot be performed. Therefore, as described above, by supplying the steam to the discharge tube 5 and then supplying the chlorofluorocarbon gas so that the steam is present during the chlorofluorocarbon decomposition,
CFC can be safely disassembled.

Further, the water vapor cannot smoothly flow in the flow passage due to the resistor 35 filled in the heater 18, and a constant amount of water vapor is always retained in the heater 18. . Therefore, it is possible to prevent scattering due to pulsation and bumping, stabilize the outflow amount of water vapor, and effectively suppress the flow rate fluctuation on the upstream side of the mixer 37. Therefore, the plasma can be stabilized without causing the plasma to disappear, and the processing capacity can be improved.

Then, the solenoid valve 19b is opened to supply the CFC gas to the discharge tube 5. At this time, the fluorocarbon gas flowing out from the recovered fluorocarbon cylinder 28 is collected by the mist separator 3
Oil and water are removed by passing through 2.
Therefore, the contamination of piping etc. and the generation of by-products due to the lubricating oil in the CFC gas are suppressed, and the CFC gas can be efficiently and stably supplied. Will not be lost. Therefore, it is possible to stabilize the plasma and improve the processing capacity.

Further, the water vapor, the argon gas, and the chlorofluorocarbon gas that have passed through the heater 18 and flowed into the mixer 37 flow out in a uniformly mixed state and are supplied to the discharge tube 5. Therefore, the decomposition reaction of Formula 1 is sufficiently performed, and the production of by-products such as chlorine gas and carbon monoxide can be suppressed.

When the Freon gas supplied to the discharge tube 5 in this way is irradiated with microwaves, the inside of the discharge tube 5 is
High electron energy and temperature of 2,000K ~
A thermal plasma of 6,000K is generated. At this time, in the discharge tube 5, not only CFC gas and water vapor,
Since argon gas is also supplied at the same time, the plasma does not disappear.

Further, since the tip of the inner tube 11 is arranged inward of the tip of the probe antenna 9a by a predetermined distance, the thermal influence of the generated plasma can be avoided,
Melt damage of the inner pipe 11 is prevented. As a result, a stable decomposition operation is possible without significant deformation of the plasma shape.

However, due to the generation of thermal plasma, the CFC gas is in a state of being easily dissociated into chlorine atoms, fluorine atoms, and hydrogen atoms, so that it is easily decomposed by reacting with water vapor as shown in Formula 1. When the plasma stabilizes, the electromagnetic valve 19a is closed to stop the supply of argon gas. Therefore, when the CFC gas is decomposed for a long time, it is not necessary to supply argon, and the consumption of argon can be suppressed to a low level.

The gas produced by the decomposition reaction is the reaction tube 15,
It is discharged into the alkaline liquid in the exhaust gas treatment tank 41 through the exchange joint 44 and the blow pipe 45. At this time, in the reaction tube 15, secondary air is mixed to cause carbon monoxide to burn and react, and is discharged as carbon dioxide. Therefore, the reaction tube 15
Is in an environment in which acid gas passes at a high temperature and is extremely corrosive, but since the cooling chamber 70 is temperature-controlled and cooled by cooling air so as not to fall below the dew point temperature, it is significantly corroded as compared with the conventional case. It can be suppressed and the life of the reaction tube 15 can be extended. The reaction tube 15 described above
When the material of the reaction tube 15 is changed to a material having a better corrosion resistance against acid gas together with the cooling of 1, the life of the reaction tube 15 can be expected to be greatly extended by the synergistic effect of both.

The product gas released into the alkaline solution through the blow pipe 45 is rendered harmless by the neutralization reaction of the equation 2. Since this neutralization reaction is an exothermic reaction, the temperature of the alkaline liquid is maintained at about 60 ° C. or lower by the cooler 53.

The produced gas released as bubbles from the tip of the blow pipe 45 is the blade 52 of the bubble dividing means 52.
Since it is finely divided upon hitting d, the contact area with the alkaline liquid increases and the time to reach the liquid surface also increases, facilitating the neutralization reaction. This prevents the amount of acid gas exceeding the standard value from being discharged out of the system due to insufficient neutralization treatment.

Of the produced gas detoxified by the neutralization reaction, the gas is discharged from the exhaust duct 42, and the gas other than the gas remains as a slurry in the alkaline liquid. After the decomposition operation is stopped, the bubble dividing means 52 is stopped, and then the treatment liquid is pumped up by the pump 53a, and the three-way valve 56 is switched to transfer it to the settling tank 62. The treatment liquid transferred to the settling tank 62 is stirred by a stirrer 62.
The aggregating agent is uniformly added while agitating at a, and the stirrer 62a is stopped to cause precipitation, and then solid-liquid separation is performed in the dehydration basket 63, the liquid content is treated as waste water, and the solid content is disposed of.
After the disassembly operation is stopped, the air compressor 24 is driven to scavenge the acidic gas remaining in the apparatus, so that the safety can be improved.

The apparatus for decomposing an organohalogen compound according to the present invention is not limited to the above-mentioned embodiment but includes the following modes.

(1) As a means for preventing the acid gas from being discharged out of the system due to insufficient neutralization treatment, the motor current value may be controlled instead of the pH control of the alkaline solution. That is, if the motor speed drops or stops,
The bubbles discharged from the blow-in pipe 45 may not be sufficiently divided and the neutralization reaction may not be sufficiently performed. Therefore, the motor rotation abnormality is detected based on the motor current value, and the control device 6
If the operation of the decomposition apparatus is stopped according to the command from No. 1, it is possible to prevent the acid gas from being discharged from the system.

(2) Instead of arranging 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 is spaced inward from the tip of the probe antenna 9a is set equal to the distance between the tip of the probe antenna 9a and the energy concentrating portion due to the microwave unless the inner tube 11 is melted. Is best, but
It may be appropriately changed in consideration of melting of the inner pipe 11.

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

[0067]

As is clear from the above description, according to the apparatus for decomposing organic halogen compounds of the present invention, the reaction tube exposed to acid gas at a high temperature is air-cooled at a cooling temperature higher than the dew point temperature. The progress of corrosion is suppressed, and the durability time of the reaction tube can be significantly extended. For this reason, it is possible to set a long interval for periodical inspection and parts replacement for the reaction tube, and to easily disassemble and remove the cooling chamber when exchanging or inspecting the reaction tube. It has a remarkable effect that it can be used repeatedly. And since the reaction tube was cooled by air cooling,
Cooling can be easily performed by circulating the cooling air. For example, pressure control and watertightness are not required as compared with water cooling that requires pressurized water, and temperature management and structure are simplified.

[Brief description of 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 an enlarged view of a main part of the disassembling apparatus.

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

FIG. 4 is a comparative diagram showing the timing of supplying microwaves, argon gas, etc. and the timing of ignition over time in the decomposition apparatus.

FIG. 5 is an exploded perspective view showing a configuration example of a cooling chamber according to the present invention.

[Explanation of symbols]

15 reaction tubes 41 Exhaust gas treatment tank 45 blow pipe 70 Cooling room 80 blower

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C07B 61/00 B01D 53/34 134E (72) Inventor Satoshi Matsuo 1 Takadō, Iwazuka-cho, Nakamura-ku, Aichi Prefecture Mitsubishi Heavy Industries Nagoya Research Institute Co., Ltd. (72) Inventor Yuji Okada 3-chome, Asahi-cho, Nishibiwajima-cho, Nishi-Kasugai-gun, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. Cooling & Heat Business Division (56) Reference JP-A-11-156144 (JP, A ) JP-A-7-24081 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01J 19/08 A62D 3/00

Claims (3)

(57) [Claims] 1. A reaction tube for decomposing an organic halogen compound, an exhaust gas treatment tank containing an alkaline solution for neutralizing decomposition products decomposed in the reaction tube, and an open lower end portion thereof are immersed in the alkaline solution. In the apparatus for decomposing an organohalogen compound, which is provided in a state of being equipped with a blow-in tube for blowing the decomposed product into the alkaline liquid from the reaction tube, a cooling chamber is formed around the reaction tube, and air is provided in the cooling chamber. An apparatus for decomposing an organohalogen compound, characterized in that it is circulated and cooled to a temperature above the dew point temperature. 2. The cooling temperature of the reaction tube is 200 ° C. to 30 ° C.
It is 0 degreeC, The decomposition | disassembly apparatus of the organohalogen compound of Claim 1 characterized by the above-mentioned. 3. The apparatus for decomposing an organohalogen compound according to claim 1, wherein the cooling chamber is dividable.