JP2000296329A - Method and device for decomposing organohalogen compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the efficient and stable supply of gaseous fluorocarbon, etc., by reducing water consumption at the decomposing process of an org. halogen compd. SOLUTION: The product gas produced by the decomposing reaction of the org. halogen compd. with steam is subjected to neutralizing reaction with alkali soln. and the resulting matter is allowed to stand for a prescribed time, and the neutralization product produced by the neutralizing reaction is precipitated in the alkali soln. and the precipitate is removed. Then a removing pipe 71 is projected at the inside of a waste gas treating tank 41 in order to for completely draw up the neutralization product, and disk plate 71a is fixed parallel to the bottom surface of the waste gas treating tank 41 at the tip of the removing pipe 71, moreover, the tip of the removing pipe 71 is opened at the center of the bottom surface of the plate 71a.

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.

[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, 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] Furthermore, as the latter apparatus for decomposing an organic halogen compound according to the plasma method, an apparatus which generates plasma using microwaves has recently been developed. The decomposition apparatus 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 cylindrical waveguide extending vertically above the reaction tube. A tube, a discharge tube disposed inside the cylindrical waveguide and penetrating the lower end thereof and communicating with the reaction tube, and a rectangular waveguide extending in the horizontal direction and connected to the cylindrical waveguide near one end thereof. It comprises a tube, a microwave transmitter mounted on the other end of the rectangular waveguide, and the like.

[0005] In this decomposition apparatus, while the Freon gas and the water vapor are supplied to the discharge tube, the microwave transmitted from the microwave transmitter 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 the decomposition reaction is neutralized by passing through the alkaline liquid, and the remaining gas including carbon dioxide gas is discharged from the exhaust duct.

[0006] When the produced gas is neutralized, neutralized products such as calcium chloride and calcium fluoride are produced, which are present as a slurry in the alkaline solution.
Since the alkaline liquid is returned to the exhaust gas treatment tank and reused, in this separation device, a solid-liquid separator is attached to the exhaust gas treatment tank, and the neutralized product present in the liquid and the alkaline liquid are separated. It has become. The neutralized product separated from the alkaline solution is disposed of as waste.

[0007]

Incidentally, in the above-mentioned decomposition apparatus, a large amount of water is used as cooling water for the reaction tube in addition to the alkaline liquid. Therefore, it is necessary to increase the solid-liquid separation efficiency of the neutralized product and the alkaline solution, and to reduce the amount of water remaining by reducing the residual amount of the alkaline solution in the neutralized product disposed as waste as much as possible. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the amount of water consumed in a process of decomposing an organic halogen compound to thereby efficiently and stably produce fluorocarbon gas and the like. To enable supply.

[0009]

Means for Solving the Problems In order to solve the above problems, the present invention employs the following constitution. Claim 1
The method for decomposing an organic halogen compound according to the present invention is to generate a thermal plasma by irradiating a gas containing the organic halogen compound with microwaves, and react with water vapor in the thermal plasma to decompose the organic halogen compound. Wherein the gas produced by the decomposition reaction between the organic halogen compound and water vapor is subjected to a neutralization reaction with an alkali solution and allowed to stand for a predetermined period of time to produce the neutralized product generated by the neutralization reaction. It is characterized in that substances are removed after being precipitated in the alkaline solution.

In this decomposition treatment method, if the produced gas is subjected to a neutralization reaction with an alkali solution and left for a predetermined time, the neutralized product generated by the neutralization reaction precipitates in the alkali solution, The product can be easily pumped up, and the efficiency of solid-liquid separation between the neutralized product and the alkaline solution increases. As a result, the recovery rate of the alkaline liquid from the neutralized product is improved, the reuse is effectively performed, and the amount of the neutralized product discarded is reduced.

According to a second aspect of the present invention, in the method for decomposing an organic halogen compound, the decomposition reaction between the organic halogen compound and water vapor is stopped, a neutralized product is removed after standing for a predetermined time, and then the decomposition reaction is stopped. It is characterized by restarting.

In this decomposition treatment method, the decomposition reaction between the organic halogen compound and water vapor is stopped to suppress the formation of the neutralized product, whereby the precipitation of the neutralized product, that is, the separation of the neutralized product from the alkaline solution is accelerated. That is, the efficiency of solid-liquid separation between the neutralized product and the alkaline solution is increased.

A third aspect of the present invention is a method for decomposing an organic halogen compound, wherein the neutralized product is subjected to solid-liquid decomposition, and the separated alkaline solution is reused in the neutralization reaction.

In this decomposition treatment method, the amount of water consumed in the decomposition treatment step is reduced by separating and reusing the alkali solution from the neutralized product conventionally discarded.

A fourth aspect of the present invention is a method for decomposing an organic halogen compound, wherein the alkaline liquid is a suspension.

In this decomposition treatment method, by using an alkaline suspension containing an alkaline substance at a high concentration, the neutralization reaction is promoted even when the volume of the alkaline solution is smaller than that of the aqueous solution.

According to a fifth aspect of the present invention, in the method for decomposing an organic halogen compound, the alkaline solution contains Ca (OH) ₂ of 20%.
It is characterized in that it is a suspension containing% by weight.

In this decomposition method, Ca (O
By using an alkaline suspension containing 20% by weight of H) ₂ , the neutralization reaction is efficiently promoted in a shorter time.

According to a sixth aspect of the present invention, the apparatus for decomposing an organic halogen compound generates thermal plasma by irradiating a gas containing the organic halogen compound with microwaves, and reacts with water vapor in the thermal plasma to convert the organic halogen compound. A decomposition apparatus for decomposing an organic halogen compound, a neutralization treatment tank filled with an alkali solution that generates a neutralized product by performing a neutralization reaction with a product gas generated by a decomposition reaction between the organic halogen compound and steam. A product gas introduction unit that introduces the product gas into the neutralization tank and reacts with the alkaline liquid;
And a neutralization product removing means for removing a neutralization product precipitated in the neutralization tank.

In this decomposition apparatus, when the produced gas is introduced into the neutralization treatment tank, it undergoes a neutralization reaction with the alkaline solution to produce a neutralized product. If the neutralization tank is left for a predetermined time in this state, the neutralized product will precipitate in the alkaline solution,
By pumping the precipitated neutralized product, solid-liquid separation from the alkaline solution is achieved.

According to a seventh aspect of the present invention, in the apparatus for decomposing an organic halogen compound, the neutralization product removing means is protruded into the neutralization treatment tank and has a tip extending to the vicinity of the bottom of the neutralization treatment tank. A pipe, and a suction pump connected to the removal pipe for sucking the neutralized product, wherein a plate is fixed to a tip of the removal pipe substantially in parallel with a bottom surface of the neutralization tank; Is characterized in that the removal tube is open at the lower surface of the slab.

In this decomposition apparatus, the neutralized product precipitated in the tank is sucked through a gap formed between the bottom surface of the neutralization tank and the plate. As a result, the neutralized products are sequentially sucked out from those accumulated near the bottom surface of the neutralization tank, thereby preventing the upper layer alkaline solution from being sucked while the neutralized products remain.

An organic halogen compound decomposing apparatus according to claim 8 is characterized in that the plate has a disk shape and the removal pipe is opened at the center of the lower surface.

In this cracker, the neutralized product is
Since the suction is performed at a substantially uniform speed from the entire periphery of the disk-shaped plate and the speed is reduced, the recovery efficiency of the neutralized product is increased.

[0025]

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 transmitter 2 for transmitting a microwave having a frequency of 2.45 GHz at a starting end (left end), and a starting end side to a terminating end (right end) side. Transmit microwave to.

As shown in FIG. 1, the rectangular waveguide 1 prevents the reflected wave from affecting the transmitting side by absorbing the microwave reflected at the terminal end and returning to the starting end. An isolator 3 and a tuner 6 for adjusting a wave-like mismatch amount of a radio wave by moving a plurality of wave adjustment members 4 in and out, respectively, and converging the radio wave to the discharge tube 5 are provided.

As shown in FIG. 2, 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. It is connected so that it may extend in the vertical direction while communicating with 1. The inner conductor 9 is fixed to the upper portion of the rectangular waveguide 1 and surrounds the discharge tube 5 made of quartz while enclosing the end plate 8 of the outer conductor 8.
A, and extend this portion to the probe antenna 9.
a.

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. 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 distal end (lower end) of the inner tube 11 is a predetermined distance away from the distal end of the probe antenna 9a.
It is arranged more inward than the tip. This distance is set to be equal to, for example, the distance between the tip of the probe antenna 9a and the energy concentration portion due to the microwave.

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 tube 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.

Then, 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.

The air is supplied from the air compressor 24 in order to remove the water remaining in the system to enhance the stability of ignition and to discharge the 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 recovered Freon cylinder 28, and the recovered Freon cylinder 28 and the solenoid 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 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. The flow path 34b on the side that generates the water vapor 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 flow smoothly through the flow path. Has become.

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. 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 (neutralization treatment tank) 41
Alkaline suspension made by adding 10% calcium hydroxide to water to neutralize and detoxify acidic gases (hydrogen fluoride and hydrogen chloride) generated when CFC gas is decomposed. (Alkaline liquid) is contained.
In the present embodiment, an alkaline suspension is used, but an alkaline aqueous solution may be used instead. However, it is desirable to use an alkaline suspension in order to quickly carry out the neutralization reaction.

For example, when the Freon gas to be decomposed is refrigerant Freon R12 recovered from a waste refrigerator, the gas produced by the decomposition reaction shown in the formula 1 is rendered harmless by the neutralization reaction shown in the formula 2. [Formula 1] CCl ₂ F ₂ + 2H ₂ O → 2HCl + 2HF + C
O ₂ [Formula 2] 2HCl + Ca (OH) ₂ → CaCl ₂ + 2H ₂ 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 a part of them is 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 (product gas introducing section) 45 connected to the reaction pipe 15 via the exchange joint 44 has a lower end vertically immersed in an alkaline solution. It is arranged to extend. The tip portion 45a of the blowing pipe 45 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 warmed by cooling the reaction tube 15 is used as a heating source of the recovered freon 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 toward the inside thereof. Cooling water is discharged from the water injection nozzle 51, and the blow tube 45 made of resin, for example, fluororesin is rapidly cooled to its heat-resistant temperature range. By the way, in the case of the blowing pipe 45 which has been processed with fluororesin, it is cooled to 100 ° C. or less.

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 of corrosion and heat resistance is required. Therefore, the life is extended by using copper.

From the tip (lower end) of the blowing pipe 45, gas generated 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 tip of the shaft 52b, and an outer edge of the blade holder 52c. And six blades 52d.

The shaft 52a and the blade holder 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.

Since the neutralization reaction of the formula 2 is an exothermic reaction, the temperature in the exhaust gas treatment tank 41
A cooler 53 is provided for cooling to a temperature lower than or equal to the heat resistant temperature of No. 5. 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 dissipates it in the heat radiating section 53b. Incidentally, the temperature in the tank is detected by the thermocouple 54.

The exhaust gas treatment tank 41 is provided with a pH sensor 55. The pH value of the alkaline solution is constantly monitored by the control device 61 via the pH sensor 55. For example, when the pH value is 9 (11 to 1 at the start of operation).
In the case of 2), the alarm means is activated by a command from the control device 61, 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, such as blinking a lamp,
Means such as honking are adopted.

Further, in the exhaust gas treatment tank 41, a neutralized product removing device (medium) for removing the neutralized product precipitated in the tank and returning the alkaline liquid contained in the neutralized product to the exhaust gas treatment tank 41 again. (Sum product removing means) 70 is provided.

As shown in FIG. 5, the neutralized product removing device 70 has a removing pipe 71 protruding into the exhaust gas treatment tank 41 for pumping the neutralized product, and a neutralizing pipe connected to the removing pipe 71 for neutralization. A suction pump 72 for sucking the product and a solid-liquid separator 73 for further performing a solid-liquid separation process on the neutralized product sucked and removed from the exhaust gas treatment tank 41 are provided.

The end of the removal pipe 71 is located at the exhaust gas treatment tank 41.
And a disk-shaped plate 71 parallel to the bottom of the exhaust gas treatment tank 41 at the tip thereof.
a is fixed, and a removing pipe 71 is provided at the center of the lower surface of the plate body 71a.
The tip is open.

The pipe connected to the removal pipe 71 is a solid-liquid separator 7.
3 and connected to the suction pump 72, and further connected to the upper part of the exhaust gas treatment tank 41 from the suction pump 72 to form a circulation system. By the way, in the solid-liquid separator 73,
For example, various types such as a centrifugal separation type, a pressure dehydration type, and a suction dehydration type are employed. Fluctuations in the liquid level in the exhaust gas treatment tank 41 are 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 Freon 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 transmitted to ignite the gas by the Tesla coil, 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. The air for this gas purge is
As shown in FIG. 2, the liquid is supplied from a supply nozzle 63 provided at an upper portion of the reaction tube 15.

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 decomposition apparatus according to the present 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, 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, a microwave is transmitted from the microwave transmitter 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, a TM01 mode having a large electric field strength is formed as an electric field in the cylindrical waveguide 7, and the electric field mode in the rectangular waveguide 1 and the electric field mode in the cylindrical waveguide 7 are formed by the inner conductor 9. 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.

This water vapor cannot flow smoothly in the flow path due to the resistor 35 filled in the heater 18, and a constant amount of water vapor 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 chlorofluorocarbon gas supplied to the discharge tube 5, 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 inside the distal end of the probe antenna 9a by a predetermined distance, the thermal effect 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, 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 steam does not re-condensate 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. In addition, the cooling water from which heat has been deprived can be reused as the cooling water for the cooler 46, and the water consumption can be reduced.

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) dissolves in the cooling water to generate an acidic liquid, the exchange joint 44 gradually corrodes. 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 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.

The neutralized product produced by the neutralization reaction is
It exists as a slurry in the alkaline liquid. Therefore,
When the disassembly operation is stopped after one day of operation, the disassembly device is left overnight. During this time, the slurry precipitates in the alkaline liquid in the exhaust gas treatment tank 41.

On the next day, when the neutralized product removing device 70 is operated before the decomposition operation is started, the slurry-like neutralized product precipitated in the exhaust gas treatment tank 41 is removed from the bottom surface of the tank and the plate 71a. The liquid is sucked through the gap formed therebetween, and is sucked up sequentially from the one that has accumulated near the bottom surface.
For this reason, a phenomenon in which a hole is formed in the neutralized product while the precipitated neutralized product is left and the alkaline solution in the upper layer is sucked from the hole is less likely to occur. In addition, the neutralized product is sucked from the entire periphery of the disc-shaped plate 71a at a substantially uniform speed, and the speed is reduced, so that only the neutralized product can be more reliably removed. become.

The neutralized product pumped from the exhaust gas treatment tank 41 is subjected to a solid-liquid separation process in a solid-liquid separator 73, and the neutralized product from which the alkaline liquid has been almost removed is disposed of as waste. Used for other purposes. On the other hand, the separated alkaline liquid is returned to the exhaust gas treatment tank 41 again through the suction pump 72 and is reused. Therefore, in the present decomposer, the water consumption is significantly reduced in combination with the reuse of the cooling water. Can be After the disassembly operation is stopped, by driving the air compressor 24,
Since the acidic gas remaining in the apparatus is scavenged, 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) 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 installed 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) As a means for preventing the acid gas from being discharged out of the system due to insufficient neutralization, the motor current value may be managed instead of the pH control of the alkaline solution. That is, when the motor speed decreases or stops,
In some cases, the bubbles released from the blowing pipe 45 are not sufficiently divided, and the neutralization reaction is not sufficiently performed. Therefore, the abnormality of the motor rotation is detected based on the motor current value, and the control device 6
If the operation of the decomposer is stopped in accordance with the command from 1, it is possible to prevent the acid gas from being discharged outside the system.

(3) Since the inside of the reaction tube 15 is kept in a dry state, there is almost no influence of corrosion by the acid gas generated by the decomposition reaction of the formula 1. However, in order to further enhance safety, a simple booth containing the reaction tube 15 is installed, and the booth and the reaction tube 1 are installed.
An exhaust gas sensor for detecting a CO ₂ gas, a CO gas or the like may be provided between the exhaust gas sensor 5 and the exhaust gas sensor 5.

In this configuration, the corrosion state of the reaction tube 15 can be constantly monitored by the control device 61 via the exhaust gas sensor. Even if the acid flows out of the system, the operation of the decomposition device is stopped by a command from the control device 61, and the generated gas that has flowed out is sucked, thereby preventing the acid gas from being discharged out of the system. In this case, the gas suction is also performed by the blower 43 provided in the exhaust duct 42.

(4) If the slurry particles are increased by adding a granulating agent, a flocculant and the like to the alkaline liquid in the exhaust gas treatment tank 41, the settling time can be shortened and the slurry treatment can be performed more efficiently. .

(5) 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. (6) Instead of heating the recovered CFC cylinder 28 to make it into a gas state and allowing the CFC gas to flow out, instead of inverting the recovered CFC cylinder 28 and allowing the recovered CFC 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.

(7) 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. (8) The distance at which the tip of the inner tube 11 is separated from the tip of the probe antenna 9a to the inside of the outer tube 12 is, as described above, the energy concentration due to the microwave with the tip of the probe antenna 9a unless the inner tube 11 is melted. It is optimal to set it equal to the distance to the part, but it may be changed as appropriate in consideration of the melting of the outer tube 12.

(9) The bubble dividing means 52 may be of a screw type in which a propeller is fixed to the tip of the 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.

(10) Instead of inclining the distal end of the blowing pipe 45 by a predetermined angle with respect to the vertical direction, the blowing pipe 45 may be formed in a substantially U-shape. (11) The neutralized liquid stored in the exhaust gas treatment tank 41 is:
Not limited to the above alkaline suspension, an alkaline aqueous solution such as an aqueous sodium hydroxide solution may be used.

[0094]

As is apparent from the above description, the present invention has the following effects. (A) According to the method for decomposing an organic halogen compound according to claim 1, when the produced gas is subjected to a neutralization reaction with an alkali solution and allowed to stand for a predetermined time, the neutralized product generated by the neutralization reaction becomes alkali. Since it precipitates in the liquid, the neutralized product can be easily pumped up, and the efficiency of solid-liquid separation between the neutralized product and the alkaline solution is increased. Thereby, the recovery rate of the alkaline solution from the neutralized product is improved, the reuse of the alkaline solution is made effective, and the amount of the neutralized product discarded can be reduced.

(B) According to the method for decomposing an organic halogen compound according to the second aspect, the decomposition reaction between the organic halogen compound and water vapor is stopped to suppress the formation of the neutralized product. The separation of the neutralized product from the alkali solution can be enhanced since the precipitation of the solution, that is, the progress of the separation from the alkali solution, is accelerated.

(C) According to the method for decomposing an organic halogen compound according to the third aspect, the amount of water consumed in the decomposition process is obtained by separating and reusing the alkali solution from the neutralized product which has been conventionally discarded. Can be reduced.

(D) According to the method for decomposing an organic halogen compound according to the fourth aspect, by using an alkaline suspension containing an alkaline substance at a high concentration, the alkaline solution has a smaller volume than an aqueous solution. Even so, the neutralization reaction can be promoted, and thereby the water consumption can be reduced.

(E) the organic halogen compound of claim 5
According to the decomposition method, Ca (OH) _TwoContaining 20% by weight
Shorter neutralization reaction by using alkaline suspension
Can be efficiently promoted on time,
Expenses can be reduced.

(F) According to the apparatus for decomposing an organic halogen compound according to the sixth aspect, when the produced gas is introduced into the neutralization treatment tank, it undergoes a neutralization reaction with the alkali solution to produce a neutralized product.
If the neutralization tank is left in this state for a predetermined period of time, the neutralized product precipitates in the alkaline solution, so that the precipitated neutralized product can be pumped up to perform solid-liquid separation from the alkaline solution.

(G) According to the apparatus for decomposing an organic halogen compound according to the seventh aspect, the neutralized product precipitated in the tank passes through the gap formed between the bottom surface and the plate of the neutralization tank. It is sucked. As a result, the neutralized products are sequentially sucked out from those accumulated near the bottom surface of the neutralization tank, and the recovery efficiency of the neutralized products accumulated in the neutralization tank can be improved.

(H) According to the apparatus for decomposing an organic halogen compound according to the eighth aspect, the neutralized product is sucked at a substantially uniform speed from the entire periphery of the disk-shaped plate, and the speed is slow. Therefore, only the neutralized product can be more reliably removed from the neutralization tank.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing an overall configuration of the disassembling apparatus.

FIG. 3 is an enlarged view of a main part of the decomposition apparatus.

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

FIG. 5 is a sectional view of a main part of a neutralized product removing device provided in the decomposition device.

FIG. 6 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.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rectangular waveguide 2 Microwave transmitter 5 Discharge tube 7 Cylindrical waveguide 13 Ignition device 15 Reaction tube 18 Heater 32 Mist separator 41 Exhaust gas treatment tank (neutralization treatment tank) Injection pipe (product gas introduction part) 70 Neutralization Product removal device (neutralized product removal means) 71 Removal tube 71a Plate 72 Suction pump 73 Solid-liquid separator

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yasuhiro Tsubaki F-term in Nagoya Laboratory, Mitsubishi Heavy Industries, Ltd. F-term (reference) 4D002 AA17 AA21 AB03 BA09 EA05 GA01 GB20 4G075 AA37 BA05 CA02 CA26 CA48 CA51 CA57 DA02 EB21 EB27 FB01 FB02 FB04 FB06

Claims (8)

[Claims] 1. A method for decomposing an organic halogen compound by generating thermal plasma by irradiating a gas containing an organic halogen compound with microwaves, and reacting the gas with water vapor in the thermal plasma to decompose the organic halogen compound. The product gas generated by the decomposition reaction of the organic halogen compound and water vapor is subjected to a neutralization reaction with an alkali solution and left for a predetermined time, and the neutralized product generated by the neutralization reaction is dissolved in the alkali solution. A method for decomposing an organic halogen compound, wherein the organic halogen compound is precipitated and removed. 2. The method according to claim 1, wherein the decomposition reaction between the organic halogen compound and water vapor is stopped, the neutralized product is removed after leaving for a predetermined time, and then the decomposition reaction is restarted. A method for decomposing an organic halogen compound. 3. The method for decomposing an organic halogen compound according to claim 1, wherein the neutralized product is subjected to solid-liquid decomposition, and the separated alkaline liquid is reused in the neutralization reaction. 4. The method for decomposing an organic halogen compound according to claim 1, wherein the alkaline liquid is a suspension. 5. The method according to claim 1, wherein the alkaline solution contains ₂ Ca (OH) ₂ .
5. The method according to claim 4, wherein the suspension contains 0% by weight. 6. An organic halogen compound decomposing apparatus for generating thermal plasma by irradiating a gas containing an organic halogen compound with microwaves, and reacting with water vapor in the thermal plasma to decompose the organic halogen compound. A neutralization tank filled with an alkaline solution that generates a neutralized product by neutralizing with a product gas generated by a decomposition reaction between the organic halogen compound and water vapor; and supplying the generated gas to the neutralization tank. An apparatus for decomposing an organic halogen compound, comprising: a product gas introduction part for introducing and reacting with the alkaline solution; and a neutralization product removing means for removing a neutralization product precipitated in the neutralization tank. 7. The removal pipe, wherein the neutralization product removal means is protruded into the neutralization treatment tank and has a tip extending to near the bottom of the neutralization treatment tank, and connected to the removal pipe. A suction pump for sucking the neutralized product, a plate body is fixed to a tip of the removal tube substantially in parallel with a bottom surface of the neutralization tank, and the removal tube is opened on a lower surface of the plate body. The apparatus for decomposing an organic halogen compound according to claim 6, characterized in that: 8. The removal plate according to claim 7, wherein the plate has a disk shape and the removal pipe is opened in the center of the lower surface.
An apparatus for decomposing an organic halogen compound according to the above.