JPH09276691A - Freon decomposition method by high frequency plasma - Google Patents

Abstract

(57) Abstract: In a CFC decomposition method using a high frequency plasma in which CFCs are hydrolyzed by a high frequency plasma decomposition reactor, a CFC decomposition method using a high frequency plasma that decomposes CFCs without generating CO or H ₂ which is a harmful substance. Is provided. In a freon decomposition method using high-frequency plasma in which freon is hydrolyzed by a high-frequency plasma decomposition reaction furnace, air is blown into the high-frequency plasma decomposition reaction furnace to hydrolyze the freon and burn H ₂ and CO to render them harmless. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decomposing CFCs by high-frequency plasma in which CFCs recovered from household refrigerators, commercial refrigerators, automobiles, etc. are hydrolyzed in a high-frequency plasma decomposition reactor.

[0002]

2. Description of the Related Art As a method for efficiently decomposing CFCs containing fluorine, chlorine, etc. in organic compounds and halogen compounds such as trichlorethylene, a method for decomposing CFCs by high-frequency plasma by hydrolyzing CFCs with high-frequency plasma to make them harmless. Is known (Japanese Patent Laid-Open No. 3-90172).
Reference).

The above-mentioned method is basically based on introducing water together with the organic halogen compound into the high frequency plasma. Since the organic halogen compound and water are efficiently diffused and introduced into the plasma, they are introduced into the argon gas. Is introduced into water by bubbling it into water, mixed with water vapor and introduced into plasma, and hydrolyzed by high heat of high frequency plasma. CFC and basic reactions of hydrolysis of the CFC substitutes, for example, Freon case of _{(CFC113) C 2 F 3 Cl} 3 + 4H 2 O = 2CO 2 + 3HF + 3HCl +
In the case of H ₂ alternative CFC (HCFC22), it is represented by CHClF ₂ + 2H ₂ O → CO ₂ + HCl + 2HF + H ₂ .

[0004]

However, when only steam is added to CFCs and alternative CFCs (hereinafter referred to as “CFCs”) and decomposed by high frequency plasma, H ₂ and CO ₂ generated by the decomposition reaction are aqueous. Due to the gasification reaction H ₂ + CO ₂ ← → CO + H ₂ O, harmful substances CO or H ₂ are generated.

Therefore, the present invention is a method for decomposing CFCs by a high-frequency plasma in which CFCs are hydrolyzed in a reactor for decomposing CFCs by a high-frequency plasma, which decomposes CFCs without generating CO or H ₂ which is a harmful substance. Is provided.

[0006]

According to the present invention, in a freon decomposition method using high frequency plasma in which freon is hydrolyzed by a high frequency plasma decomposition reaction furnace, air is blown into the high frequency plasma decomposition reaction furnace to hydrolyze the freon and Burns ₂ and CO to make them harmless.

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 according to the following reaction formula to be harmless. To be done.

CO + H ₂ + 1 / 2O ₂ → CO ₂ + H ₂ O The air blown into the high frequency plasma decomposition reaction furnace is blown into the plasma main body, or the high frequency plasma decomposition reaction furnace from the shoulder of the high frequency plasma decomposition reaction furnace, which corresponds to the lower part of the high frequency plasma, is used. The mixing property of air can be further enhanced by blowing it into a swirling flow along the inner furnace wall.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a flow chart of a CFC decomposition method using high frequency plasma according to the present invention. Freon is
The recovered Freon cylinder is heated with warm water in a Freon evaporator to form gaseous Freon and supplied, and is heated to about 145 ° C by the heater 1.

Heated CFC is about 145 with heater 2.
The mixed gas of chlorofluorocarbon and steam is heated to 160 to 180 ° C by the mixed gas heater 3 and mixed with the steam heated to ° C, and is supplied to the high-frequency plasma decomposition reaction furnace 4.

Air for burning the H ₂ and CO generated by the decomposition reaction to render them harmless is supplied from the shoulder of the high frequency plasma decomposition reaction furnace 4 at room temperature. A part of the air is added to the mixed gas of Freon and water vapor to stabilize the plasma.

The flow rates of CFCs, steam and air are adjusted to predetermined flow rates by controlling the flow rate adjusting valve with a flow rate controller FIC.

The high frequency plasma decomposition reactor 4 is made of a refractory material such as high alumina, has a plasma torch 5 activated by argon gas at the head of the furnace, and has a furnace pressure of 200 Torr.
Keep r to 400 Torr.

At the bottom of the high frequency plasma decomposition reactor 4,
A cooling can 6 is provided for cooling the exhaust gas generated in the furnace,
In the throat 7 between the high frequency plasma decomposition reactor 4 and the cooling can 6, the decomposition gas is cooled by the cooling can circulating liquid,
absorbs 1 and HF.

Exhaust gas from the cooling can is sent to an exhaust gas treatment facility,
The circulating fluid in the cooling can is sent to the wastewater treatment facility.

FIG. 2 is a cross-sectional view of the furnace wall of the high-frequency plasma decomposition reaction furnace for blowing air in a swirl flow. Air is blown into the furnace wall of the high-frequency plasma decomposition reaction furnace 4 through a blowing port 8
It is blown into a swirling flow along the furnace wall.

[0017]

[Example] The processing conditions are as follows.

HCFC22 throughput ... 36-50 Kg / h H ₂ O / CFC mole ratio ... 2.2-3.5 Air insertion rate ... 518 Nl / min Furnace pressure ... ...... in 200~400Torr the conditions for combusting H ₂ and CO, and the theoretical amount of air required for combustion of the H ₂ and CO that occurs when the air ratio of the insertion air (HCFC22 is hydrolyzed The change of the air insertion ratio and the amount of CO generated when the ratio of the actually inserted air amount) was changed to 1.0, 1.2, 1.4 is as shown in FIG. It can be seen that the CO generation amount decreases as the amount of air directly inserted into the furnace increases.

[0019]

EFFECTS OF THE INVENTION By inserting air into a high-frequency plasma decomposition reactor for hydrolyzing CFCs, CO and H ₂ can be burned and harmful CO and H ₂ can be suppressed.

[Brief description of drawings]

FIG. 1 is a flow chart 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 reaction furnace 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 Blowing port

Claims (2)

[Claims] 1. In a freon decomposition method using high-frequency plasma in which freon is hydrolyzed by a high-frequency plasma decomposition reaction furnace, air is blown into the high-frequency plasma decomposition reaction furnace to hydrolyze the freon and burn H ₂ and CO ₂ to cause no harm. A method for decomposing CFCs by high-frequency plasma, which is characterized by 2. The method for decomposing CFCs by high-frequency plasma according to claim 1, wherein air is blown into the high-frequency plasma decomposition reaction furnace in a swirling flow along the furnace wall in the high-frequency plasma decomposition reaction furnace.