JPH09148096A - Fluorocarbon decomposing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorocarbon decomposing method which can be operated at a low running cost, provides a low equipment cost, and allows the device to be constructed in a small size. SOLUTION: A plasma gas generating device concerned 2 uses air as plasma gas, in which fron is put into the gap between electrodes 3a, 3b of a torch 3 and exposed directly to the high temp. plasma. Thereby the fluorocarbon is put reacting with the oxygen in the plasma gas and rapidly cooled while it is passed through an alkali water solutin. Water is added to the fluorocarbon and is allowed to react with the fluorocarbon decomposed by the heat of high temp. plasma.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CFC decomposing method for decomposing appropriately recovered CFC by a plasma reaction method.

[0002]

2. Description of the Related Art Conventionally, as a CFC decomposition method for decomposing CFCs by a plasma reaction method, Japanese Patent Laid-Open No. 3-89499.
As disclosed in the publication, there is disclosed a device in which a mixed gas containing freon is introduced into a tube through a gas supply nozzle and the freon is decomposed by the action of plasma generated in the tube.

[0003]

However, in the above-mentioned prior art, in order to decompose fluorocarbons with high efficiency,
There is a problem that a gas with a high running cost such as argon, hydrogen, and oxygen is required, and the structure such as a high-frequency generator is complicated, leading to an increase in the size of the device and being expensive.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method which is simple in structure, inexpensive, and capable of decomposing CFCs with high efficiency.

[0005]

The method for decomposing CFCs according to claim 1 of the present invention is a plasma generator which uses air as a plasma gas, wherein CFCs are introduced between the electrodes of the torch to increase the heat of the plasma. The fluorocarbon is directly exposed to react with the oxygen in the plasma gas, and then the fluorocarbon is treated while being rapidly cooled through an aqueous alkali solution.

In the method for decomposing CFCs according to the second aspect of the present invention, water is added to CFCs, and the water is reacted with CFCs decomposed by the high heat of plasma.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic structure of an apparatus for carrying out the CFC decomposition method of the present invention.

In FIG. 1, reference numeral 1 is a decomposition chamber, and a plasma torch 3 connected to a plasma generator 2 is provided above the decomposition chamber 1.

A cooling chamber 4 is arranged on the outer periphery of the decomposition chamber 1, and cooling water can be circulated by a pump (not shown). The circulation of the cooling water cools the decomposition chamber 1.

The plasma torch 3 has a negative electrode 3a and a positive electrode 3b, the negative electrode 3a is disposed on the upper side, and the positive electrode 3b is provided below the negative electrode 3a. Are arranged at intervals.

The negative electrode 3a and the positive electrode 3b are
It is electrically connected to the plasma generator 2.

From the plasma generator 2, an air supply pipe 5 is connected to the periphery of the negative electrode 3a in order to use air as plasma gas.

A fluorocarbon cylinder 6 containing a fluorocarbon is connected to the plasma torch 3 through a supply pipe 7.

The supply pipe 7 is in communication with a space 8 formed between the negative electrode 3a and the positive electrode 3b.

A water tank 9 is provided in the middle of the supply pipe 7.
Is connected to the water supply pipe 10, and the water in the water tank 9 is supplied to the supply pipe 7 by the pump 11 provided in the water supply pipe 10.

The lower end of the decomposition chamber 1 is submerged in a water tank 12 in which an alkaline aqueous solution is stored, and the products produced by the decomposition of CFCs in the division chamber 1 are stored in the water tank 1.
After being led to the bottom of No. 2, it is made to react with the alkaline aqueous solution by passing it through the alkaline aqueous solution.

A discharge pipe 13 is connected to the upper portion of the water tank 12 to discharge the reaction product that has reacted with the alkaline aqueous solution.

The discharge pipe 13 is provided with another processing device 14 if necessary, and the other end is open to the outside air.

Reference numeral 15 shown in FIG. 1 is a flow rate adjusting valve provided in the supply pipe 7, and 16 is a heater.

Next, the CFC decomposition method of the present invention carried out by the apparatus thus constructed will be described.

CFCs are supplied to the space 8 from the CFC cylinder 6 through the supply pipe 7, and the CFCs are directly exposed to the high heat of the plasma generated by the plasma generator 2 from the air as plasma gas. Reacts with oxygen in gas.

Subsequently, the above reaction product is reacted with CFCs together with water supplied through the supply pipe 7, and then treated with an alkaline aqueous solution while being rapidly cooled.

As a result, CFCs are processed and the discharge pipe 13
After that, it is discharged after being subjected to the subsequent processing in the processing device 14 as required.

As described above, in this method, air is used as the plasma gas, and since expensive gas such as argon Ar or hydrogen is not used, running cost is easy.
In addition, since no high frequency generator is used, the equipment cost is low,
In addition, the size of the device can be reduced.

FIG. 2 shows another schematic structure of the CFC decomposition apparatus.

In FIG. 2, reference numeral 20 denotes a decomposition chamber, and a plasma torch 21 is provided on one side of the decomposition chamber 20. The plasma torch 21 is connected to a plasma generation device 22 and is configured so that the plasma generation device 22 can irradiate plasma into the decomposition chamber 20 via the plasma torch 21.

An injection nozzle 23 for injecting CFCs is provided on the side of the decomposition chamber 20 facing the plasma torch 21. The injection nozzle 23 is in communication with a Freon storage cylinder 25 via a press-fitting pump 24.

The chlorofluorocarbon storage cylinder 25 stores the chlorofluorocarbon that has been appropriately recovered, and the chlorofluorocarbon is injected from the injection nozzle 23 at a predetermined pressure by the operation of the press-fitting pump 24.

A flow rate adjusting valve 26 with pressure guarantee is provided at the base end of the injection nozzle 23, and CFC is injected into the decomposition chamber 20 while maintaining a predetermined pressure by the flow rate adjusting valve 26 with pressure guarantee. It

These injection nozzle 23, press-fitting pump 24,
Fluorocarbon storage cylinder 25 and flow rate control valve 26 with pressure guarantee
Thus, a CFC ejecting device A for ejecting CFC into the decomposition chamber 20 at a predetermined pressure is configured.

Further, the press-fitting pump 2 is installed in the decomposition chamber 20.
An oxygen cylinder 28 is communicated with the oxygen cylinder 28 through the valve 7, and oxygen is supplied from the oxygen cylinder 28 into the decomposition chamber 20 at a predetermined pressure by the operation of the press-fitting pump 27.

The oxygen supply section 30 of the decomposition chamber 20 is provided with a pressure-guaranteed flow rate adjusting valve 29, which supplies oxygen into the decomposition chamber 20 while maintaining a predetermined pressure. To be done. The gas supplied into the decomposition chamber 20 is not limited to oxygen and may be compressed air.

These press-fitting pump 27, oxygen cylinder 28,
The pressure-guaranteed flow rate adjusting valve 29 and the oxygen supply unit 30 constitute a supply device B that supplies oxygen to the decomposition chamber 1 at a predetermined pressure.

Further, in the decomposition chamber 20, the decomposition chamber 2
A discharge part 31 for discharging the gas decomposed at 0 and the mixed gas of undecomposed fluorocarbon is formed, and this discharge part 31 is connected to the separation device 33 via a flow rate control valve 32 with pressure guarantee.

The separating device 33 liquefies and separates CFCs from the mixed gas. By passing cooling water through the cooling pipe 33b provided in the device body 33a, the mixed gas introduced into the device body 33a is discharged. It is cooled, and chlorofluorocarbon is liquefied and separated by utilizing the temperature difference.

The liquefied and separated flon is heated by the heating device 34.
It is gasified again by being heated by and is returned to the CFC storage cylinder 25.

In FIG. 1, reference numeral 35 is a pipe for sampling or sampling, which is provided in the separation device, or for release into the atmosphere.
An opening / closing valve 36 is interposed in the pipe 35. Further, 37 is a check valve, and 38 is a pressure gauge arranged at an appropriate position.

Next, the decomposition of CFCs by the CFC decomposition apparatus thus constructed will be described.

First, by operating the plasma generator 22, the plasma generated by the plasma generator 22 is applied to the inside of the decomposition chamber 20 by the plasma torch 21, and in this state, it is collected from the fluorocarbon storage cylinder 25 to the fluorocarbon storage cylinder 25. The stored freon is injected from the injection nozzle 23 toward the plasma torch 21 through the pressure-guaranteed flow rate adjusting valve 26 while being pressurized to a predetermined pressure by the press-fitting pump 24.

At this time, the oxygen cylinder 2 is placed in the decomposition chamber 20.
Oxygen (or air) is supplied from 8 in a state of being pressurized to a predetermined pressure by a press-fitting pump 27, and the supply of this oxygen irradiates the plasma torch 21 with CFCs injected toward the plasma torch 21. Decomposed well by plasma. By directly injecting CFCs into plasma in this way, CFCs can be satisfactorily decomposed with a simple configuration.

The pressure and the flow rate of the CFC and oxygen supply are set so that the CFC is decomposed in a good condition.
It may be set appropriately while checking.

Then, the gas decomposed as described above and the CFCs partially remaining without being decomposed are decomposed into the decomposition chamber 2
It is introduced into the separation device 33 from the discharge unit 31 of 0.

In the separating device 33, only the CFCs are liquefied by the cooling action of the cooling water and separated from other gases.

The separated fluorocarbons are introduced into the heating device 34, gasified again by the heating device 34, and then returned to the fluorocarbon storage cylinder 25, where they are decomposed in the same manner as described above.

After repeating the CFC decomposition in this manner,
From the pipe 35 of the separation device 33, the gas inside the separation device 33 is checked for harmfulness, and if there is no harmfulness, this gas is discharged from the pipe 35 to the atmosphere.

[0047]

As described above, according to the CFC decomposition method of the present invention, since air is used as the plasma gas and expensive gas such as argon or hydrogen is not used, the running cost is easy, and Since no high-frequency generator is used, the facility cost is low, the device can be downsized, and the fluorocarbon can be efficiently decomposed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an apparatus for carrying out a Freon decomposition method of the present invention.

FIG. 2 is a diagram showing another schematic configuration of a CFC decomposition apparatus.

[Explanation of symbols]

 1 Decomposition chamber 2 Plasma generator 3 Plasma torch 12 Water tank

Claims (2)

[Claims] 1. A plasma generator using air as a plasma gas, wherein CFCs are introduced between electrodes of a torch to directly expose the CFCs to the high heat of plasma to cause the CFCs to react with oxygen in the plasma gas. After that, the method for decomposing CFCs is characterized in that it is treated while being rapidly cooled by passing it through an alkaline aqueous solution. 2. The method for decomposing fluorocarbons according to claim 1, wherein water is added to the fluorocarbons and the water is reacted with the fluorocarbons decomposed by high heat of plasma.