JP3965216B2 - CFC decomposition method using high frequency plasma - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a freon decomposing method using high-frequency plasma in which flon recovered from a home refrigerator, commercial refrigerator, automobile, or the like is hydrolyzed in a high-frequency plasma decomposition reactor.
[0002]
[Prior art]
As a method for efficiently decomposing halogen compounds such as chlorofluorocarbons and trichloroethylene containing fluorine and chlorine in organic compounds, a chlorofluorocarbon decomposing method using high frequency plasma that hydrolyzes chlorofluorocarbon using detoxification is known. (See JP-A-3-90172).
[0003]
The above method is based on introducing water together with an organic halogen compound into the high-frequency plasma, and the organic halogen compound and water are efficiently diffused and introduced into the plasma. A compound is introduced into water and bubbled to convert the organic halogen compound into vapor, mixed with water vapor, introduced into the plasma, and hydrolyzed by the high heat of the high-frequency plasma.
The basic reaction of the hydrolysis of Freon and alternative Freon is, for example,
In the case of chlorofluorocarbon (CFC113), C ₂ F ₃ Cl ₃ + 4H ₂ O = 2CO ₂ + 3HF + 3HCl + H ₂
In case of CFC substitute (HCFC22) CHClF ₂ + 2H ₂ O → CO ₂ + HCl + 2HF + H ₂
It is represented by
[0004]
[Problems to be solved by the invention]
However, when only water vapor is added to chlorofluorocarbon and alternative chlorofluorocarbon (hereinafter referred to as chlorofluorocarbon) and decomposed by high-frequency plasma, H ₂ and CO ₂ generated by the decomposition reaction are converted into water gasification reaction H ₂ + CO ₂ ← → CO + H ₂ O
As a result, CO or H ₂ which is a harmful substance is generated.
[0005]
Accordingly, the present invention provides a freon decomposing method using high-frequency plasma, in which freon is decomposed without generating CO or H ₂ , which are harmful substances, in a freon decomposing method using high-frequency plasma in which freon is hydrolyzed by a high-frequency plasma decomposition reactor. Is.
[0006]
[Means for Solving the Problems]
The present invention relates to a freon decomposing method using high-frequency plasma in which freon is hydrolyzed by a high-frequency plasma decomposition reactor. The recovered flon cylinder is heated with hot water in a freon evaporator to form gaseous freon, and the gaseous flon and water vapor are mixed. Then, the mixed gas is heated to 160 to 180 ° C. and supplied to the high-frequency plasma decomposition furnace, and air is supplied from the shoulder of the high-frequency plasma decomposition reaction furnace at room temperature, and a part of the air is added to the mixed gas. It is blown into a high-frequency plasma decomposition reactor to hydrolyze chlorofluorocarbon and burn H ₂ and CO to make them harmless.
[0007]
When air is blown into the high frequency plasma decomposition reaction furnace, CO and H ₂ generated in the high frequency plasma decomposition reaction furnace and O ₂ in the blown air are burned by the following reaction expression and rendered harmless.
[0008]
CO + H ₂ + O ₂ → CO ₂ + H ₂ O
The air to be blown into the high-frequency plasma decomposition reactor is blown into the plasma main body, or blown as a swirling flow along the furnace wall in the high-frequency plasma decomposition reactor from the shoulder of the high-frequency plasma decomposition reactor that hits the lower part of the high-frequency plasma. The mixing property can be further increased.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a flow diagram of a CFC decomposition method using high-frequency plasma according to the present invention. Fluorocarbon is heated and heated to about 145 ° C. with heater 1 by heating the recovered CFC cylinder with hot water in a CFC evaporator to form gaseous CFC.
[0010]
The heated chlorofluorocarbon is mixed with water vapor heated to about 145 ° C. by the heater 2, and the mixed gas of chlorofluorocarbon and water vapor is heated to 160 to 180 ° C. by the mixed gas heater 3, and is sent to the high-frequency plasma decomposition reactor 4. Supply.
[0011]
Air for detoxifying H ₂ and CO generated by the decomposition reaction is supplied from the shoulder of the high-frequency plasma decomposition reactor 4 at normal temperature. Part of the air is added to the mixed gas of CFC and water vapor to stabilize the plasma.
[0012]
The flow rates of chlorofluorocarbon, water vapor, and air are adjusted to a predetermined flow rate by controlling the flow rate adjustment valve with a flow rate controller FIC.
[0013]
The high-frequency plasma decomposition reactor 4 is made of a refractory such as high alumina, and has a plasma torch 5 activated by argon gas at the head of the furnace, and the pressure in the furnace is maintained at 200 Torr to 400 Torr.
[0014]
A cooling can 6 for cooling the exhaust gas generated in the furnace is provided at the lower part of the high-frequency plasma decomposition reaction furnace 4, and the decomposition gas is generated by the cooling can circulating liquid in the throat 7 between the high-frequency plasma decomposition reaction furnace 4 and the cooling can 6. Is cooled and absorbs HCl and HF.
[0015]
The exhaust gas exiting the cooling can is sent to the exhaust gas treatment facility, and the cooling can circulating liquid is sent to the waste water treatment facility.
[0016]
FIG. 2 is a cross-sectional view of the furnace wall of the high-frequency plasma decomposition reactor for blowing air in a swirl flow. Air flows along the furnace wall from the inlet 8 provided in the furnace wall of the high-frequency plasma decomposition reactor 4. It is blown as a swirl flow.
[0017]
【Example】
The processing conditions are as follows.
[0018]
HCFC22 throughput: 36-50Kg / h
H ₂ O / CFC molar ratio: 2.2 to 3.5
Air insertion amount ... 518 Nl / min furnace pressure ... 200 to 400 Torr
In order to burn H ₂ and CO under the above-mentioned conditions, the air ratio of the inserted air (the ratio of the theoretical air amount necessary for the combustion of H ₂ and CO generated when the HCFC 22 is hydrolyzed and the actually inserted air amount) ) Is changed to 1.0, 1.2, and 1.4, the change in the air insertion ratio and the amount of CO generated is as shown in FIG. 3, and a large amount of air is directly inserted into the high-frequency plasma decomposition reactor. It turns out that the amount of CO generated becomes smaller.
[0019]
【The invention's effect】
By inserting air into a high-frequency plasma decomposition reactor that hydrolyzes chlorofluorocarbon, CO and H ₂ can be burned, and generation of harmful CO and H ₂ can be suppressed.
[Brief description of the drawings]
FIG. 1 is a flow diagram of a CFC decomposition method using high-frequency plasma according to the present invention.
FIG. 2 is a cross-sectional view of a furnace wall of a high-frequency plasma decomposition reactor for blowing air in a swirling flow.
FIG. 3 is a graph showing changes in air insertion ratio and CO generation amount.
[Explanation of symbols]
1 Heater 2 Heater 3 Mixed Gas Heater 4 High Frequency Plasma Decomposition Reactor 5 Plasma Torch 6 Cooling Can 7 Throat 8 Inlet

Claims (1)

In a freon decomposing method using high-frequency plasma in which freon is hydrolyzed by a high-frequency plasma decomposition reactor, the recovered flon cylinder is heated with hot water in a freon evaporator to form gaseous freon, and the gaseous flon and water vapor are mixed and mixed gas Is heated to 160 to 180 ° C. and supplied to the high-frequency plasma decomposition furnace, and air is supplied from the shoulder of the high-frequency plasma decomposition reaction furnace at room temperature, and a part of the air is added to the mixed gas and the high-frequency plasma decomposition reaction. A freon decomposing method using high-frequency plasma, wherein the freon is hydrolyzed by blowing into a furnace, and H ₂ and CO are burned to make them harmless.

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