JP2002166165A - Method of decomposing fluorocarbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorocarbon decomposing method capable of continuously and safely decomposing fluorocarbon, which is a substance destroying an ozone layer, without adding special equipment by using a waste melting furnace or a combustion chamber installed after it. SOLUTION: Collected fluorocarbon is gasified and evaporated by an evaporator, and then the evaporated fluorocarbon or a mixture mixed with steam by a mixer is introduced into a high-temperature part in the lower part of the waste melting furnace from a dedicated injection port. Thereby the fluorocarbon is hydrolyzed and oxidatively decomposed at a high temperature.

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 recovered from household refrigerators, commercial refrigerators, automobiles, etc., and more particularly to a technique for decomposing CFCs using a waste melting furnace.

[0002]

2. Description of the Related Art Ultra-high-temperature hydrolysis using high-frequency plasma, supercritical decomposition using a rotary kiln as an industrial waste incinerator, and the like have been proposed as methods for decomposing CFCs, which are ozone-depleting substances. Alternatively, there has been proposed a method of decomposing chlorofluorocarbon by introducing the gas from a tuyere of an impact wind of a gasification melting furnace or a coke type direct melting furnace.

[0003]

Among these decomposition methods, in the plasma decomposition method and the supercritical decomposition method, a special facility must be provided for decomposing CFCs, and the processing cost is high economically. There is a disadvantage that it sticks.

[0004] In the decomposition method using a rotary kiln, the temperature in the furnace of the rotary kiln must be maintained at about 800 ° C. or more, which is a temperature required for decomposing CFCs. This temperature generates clinker in the kiln. It is close to the temperature and puts a burden on the operation of the original waste treatment furnace. Further, when the kiln is operated with the clinker melting temperature of 1,200 ° C. or higher, there is a problem that refractories in the furnace may be damaged.

Accordingly, the present invention utilizes a waste melting furnace or a combustion chamber provided at the subsequent stage to continuously and safely decompose the chlorofluorocarbon, which is an ozone depleting substance, without adding any special equipment. The present invention provides a method for decomposing CFCs.

[0006]

SUMMARY OF THE INVENTION According to the present invention, the recovered chlorofluorocarbon is gasified and evaporated in an evaporator, and then the vaporized chlorofluorocarbon is mixed with steam alone or in a mixer, and the high temperature of the lower part in the waste melting furnace is reduced. This is a method for decomposing chlorofluorocarbon using a waste melting furnace, which introduces the chlorofluorocarbon into the furnace through a dedicated injection port and hydrolyzes and oxidizes and decomposes the chlorofluorocarbon at a high temperature.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the waste treatment using a shaft furnace type waste melting furnace, general waste or industrial waste, etc. charged in the furnace is dried, thermally decomposed, burned, melted, and disposed. Items are taken out as slag.

[0008] The melting furnace has a shaft-shaped furnace body having a circular cross section, and burns coke as a fuel in order to dry, pyrolyze, burn and melt the waste charged in the furnace. . A plurality of tuyeres are usually provided for coke combustion, and air is blown from the tuyeres.

[0009] In the operation of the waste melting furnace, combustible components in the charge are thermally decomposed in the furnace to generate residues. The generated pyrolysis residue is burned by air sent from the tuyere or melted in a furnace. Further, the gas generated by the thermal decomposition is discharged from the upper part of the furnace, and is completely burned in a combustion furnace installed at a later stage.

The temperature at the lower part of the waste melting furnace is such that the normal operating temperature is about 1,200 ° C. to 1,600 ° C., and the retention decomposition time is about 0.5 to 2 seconds.

[0011] By introducing an amount of chlorofluorocarbon which does not hinder the melting operation and the components of the smelting furnace, the chlorofluorocarbon can be decomposed.

The chlorofluorocarbon used as the refrigerant is collected in a collection cylinder (1 kg to 1 ton) by a chlorofluorocarbon collection device. Although the boiling point of chlorofluorocarbon varies depending on the composition, in the present invention, for those having a boiling point of less than 40 ° C, the recovered chlorofluorocarbon is heated at a temperature of less than 40 ° C according to the high-pressure gas control method with warm water or hot air, so that the inside of the cylinder is reduced. Evaporate Freon. Further, those having a boiling point of 40 ° C. or more are extracted in a liquid phase using a pump and evaporated using an evaporator (heat exchanger). The evaporated chlorofluorocarbon is mixed with an amount of water vapor required for chlorofluorocarbon decomposition by the evaporated fluorocarbon alone or by a mixer.
When introduced into a melting furnace in a temperature range of about 00 ° C., the decomposition reaction proceeds in the high-temperature part at the lower part of the waste melting furnace, which is maintained at a temperature much higher than 800 ° C., which is the decomposition temperature of chlorofluorocarbons without a catalyst. Decomposed into hydrofluoric acid, hydrochloric acid, water or carbon dioxide gas.

The decomposition of chlorofluorocarbon requires a hydrogen source and an oxygen source in order to suppress the generation of toxic gases. Therefore, the decomposition reaction proceeds by reacting water (steam) having both atoms and air containing oxygen at a high temperature together with Freon. Examples of the chlorofluorocarbon decomposition reaction are shown below.

(1) Reaction in the case of CFC-11 CCl ₃ F + 2H ₂ O → CO ₂ + 3HCl + HF (2) Reaction in the case of CFC-12 CCl ₂ F ₂ + 2H ₂ O → CO ₂ + 2HCl + 2HF (3) Reaction of CFC-113 Reaction in case C ₂ Cl ₃ F ₃ + 4H ₂ O + 0.5O ₂ → 2CO ₂ +3
_{HCl + 3HF + H 2 O (} 4) reaction when the _{CFC-114 C 2 Cl 2 F4} + 4H 2 O + 0.5O 2 → 2CO 2 +2
HCl + 4HF + H ₂ O (5) Reaction in the case of CFC-115 C ₂ ClF ₅ + 4H ₂ O + 0.5O ₂ → 2CO ₂ + HC
1 + 5HF + H ₂ O (6) Reaction in case of HCFC-22 CHClF ₂ + 2H ₂ O + 0.5O ₂ → CO ₂ + HCl
+ 2HF + H ₂ O In general, the decomposition of chlorofluorocarbon is required to be 800 ° C. or more in the case of no catalyst, but in the present invention, the temperature is maintained at a temperature much higher than the chlorofluorocarbon decomposition temperature in the case of no catalyst of about 800 ° C. Since the melting furnace is used, the high temperature required for the decomposition of chlorofluorocarbon can be easily obtained without any need for a new heat source from outside the system.

[0015]

An embodiment of the present invention will be described with reference to FIG.

CFCs used as a refrigerant and the like are collected and stored in a CFC cylinder 1 (1 kg to 1 ton) by a CFC recovery machine. In the case of fluorocarbon having a boiling point of less than 40 ° C., the cylinder is heated by the fluorocarbon evaporator 2 and the fluorocarbon in the cylinder evaporates. In this case, the chlorofluorocarbon evaporator may be any of a hot tub type, a hot water spraying type and a hot air heating type. The evaporated Freon is heated by the heater 3. Boiling point 40 ° C
In the case of the above-mentioned fluorocarbon, which is in the liquid phase, it is sucked out by the pump 4 and sent to the evaporator 5 (about 165 ° C.) to evaporate. The evaporated CFCs are heated by the heater 6 (about 160
C.) and heated and mixed in a CFC mixer 7.
The required amount of water vapor is CF ₂ C
For l _2, more than twice the CFC-12 moles and preferably about 3 times is preferable. Decomposition is improved by increasing the partial pressure of steam. Similarly, in the case of other fluorocarbons, the number of moles of steam that is 1.0 to 1.5 times or more the number of moles required for the reaction is preferable for the decomposition reaction. The chlorofluorocarbon mixed with the steam is introduced into the waste melting furnace 8 through a dedicated injection port. The chlorofluorocarbon introduced into the lower part 9 of the melting furnace has a lower temperature 12
At a temperature of 00 ° C to 1600 ° C and a residence time of 0.5 to 1 second,
% Or more. Hydrochloric acid and hydrofluoric acid in the cracked gas are mostly absorbed by the following reaction by blowing slaked lime into a duct arranged on the downstream side of the melting furnace, and the others are released to the atmosphere.

CaO + 2HCl → CaCl ₂ + H ₂ OC
aO + 2HF → CaF ₂ + H ₂ O In the above embodiment, the steam heated by the heater is added to the Freon after the evaporator 5 and then mixed. However, in the present invention, the addition and mixing of the steam is required in the present invention. It is good to decide whether or not to do so in the following way.

As described above, water (steam) is required for the decomposition of chlorofluorocarbon. On the other hand, air 11 and 12 as a melting and burning action are introduced (supplied) from outside the system into the waste melting furnace 8. The air for combustion contains water (steam) necessary for the decomposition of chlorofluorocarbons, and the humidity is high during rainy and rainy season. In this case, the amount of water (steam) required for the decomposition of chlorofluorocarbons is introduced. Although it depends on the amount of air and the amount of chlorofluorocarbon to be treated, basically the moisture in the introduced air is sufficient, and the addition of water vapor as described in the above embodiment becomes unnecessary.

Conversely, when the amount of water (steam) necessary for the decomposition of chlorofluorocarbon is insufficient due to the dryness of the air and the low humidity in winter, etc. Good.

In short, it is determined whether or not a steam amount of 1.0 to 3.0 times the number of moles required for the reaction of chlorofluorocarbon calculated by the above-mentioned various reaction formulas is secured with respect to the chlorofluorocarbon throughput. A trial calculation is made based on the amount of air introduced during operation, the humidity of the air, and the like. If insufficient, steam may be added.

Next, as a place for introducing the chlorofluorocarbon after the evaporation, in the above-mentioned embodiment, it is appropriate to introduce the chlorofluorocarbon through a dedicated injection port into the lower part of the melting furnace. Further, since a residence time of 0.5 to 2 seconds or 2 seconds or more is obtained, decomposition of CFCs is possible.

[0022]

According to the present invention, about 1,200 ° C. to 1,60 ° C.
Since the melting furnace maintained at 0 ° C. is used, the high temperature required for the decomposition of chlorofluorocarbon can be easily obtained without requiring any new heat source from outside the system.

According to the present invention, CFCs can be inexpensively and safely processed using an existing waste melting furnace without using any specific processing equipment.

In addition, incineration methods such as stoker furnaces and fluidized-bed furnaces for general and industrial wastes, as well as in the upper, middle and lower parts of a high-temperature furnace of a gasification and melting furnace, directly or directly as a fluorocarbon evaporator. By blowing in the fluorocarbon evaporated by the device, residual oxygen, residual steam, moisture,
Also, a method of reacting the generated steam or water in the furnace is an epoch-making invention.

It is also within the scope of the present invention to blow fluorocarbon directly into the upper, middle or lower coke layer of the coke type direct melting furnace, or to blow fluorocarbon vaporized by an evaporator. In this case, the coke layer at the blowing port may be at room temperature or low temperature. This room temperature or low temperature coke layer contains water and steam, and may further contain oxygen, and in this state, CFC flows into the high temperature coke layer together with the water, steam and oxygen and is decomposed.

In the case where the chlorofluorocarbon is directly blown as it is or when the chlorofluorocarbon is vaporized, a method of mixing or mixing a liquid such as water or a gas such as vapor or gas into the fluorocarbon may be used. In this case, CFCs are more easily reacted.

CFCs are directly or indirectly blown into the top, upper, middle, and lower parts of a coke-type direct melting furnace or incinerator by a vaporizer utilizing exhaust heat from the furnace to evaporate. , Flow along with the gas such as water and steam in the furnace and gas in the furnace, in the next step, for example, in a high temperature process such as a combustion chamber, a heating furnace or a boiler,
The method of decomposing is also one of the present invention.

Further, it is also possible to blow gaseous chlorofluorocarbon directly or as a vaporized chlorofluorocarbon into a high-temperature molten metal or a molten material generated in a gasification melting furnace or a direct melting furnace. In this case, the oxygen in the melt contributes to the oxidative decomposition reaction of the chlorofluorocarbon, and the chlorofluorocarbon decomposition is strongly promoted by contact with the high-temperature furnace gas and the molten material. This CFC decomposition method is a revolutionary invention.

[0029]

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of the present invention.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Freon cylinder 2 Freon evaporator 3 Heater 4 Pump 5 Evaporator 6 Heater 7 Freon mixer 8 Waste melting furnace 9 Lower part of waste melting furnace 10 Combustion furnace

Claims (5)

[Claims] 1. A gasification fluorocarbon obtained by evaporating fluorocarbon directly as it is or by a fluorocarbon evaporator is converted into a special incinerator or melting furnace provided at a lower, middle or upper part of a general waste or an industrial waste. A method for decomposing chlorofluorocarbons using a melting furnace, characterized in that chlorofluorocarbons are hydrolyzed at a high temperature by injecting them into the furnace through an injection port. 2. CFCs are blown into the upper, middle and lower coke layers of a coke-type direct melting furnace through a dedicated blow-in port. Method of hydrolysis or oxidative degradation 3. Mixing gasified chlorofluorocarbon, which is obtained by evaporating chlorofluorocarbon directly or directly with a chlorofluorocarbon evaporator, with a liquid such as water or a gas containing vapor or vapor in the upper, middle or lower part of a coke type direct melting furnace. A method of decomposing CFCs by injecting or mixing and injecting them through a dedicated blowing port 4. A method of directly injecting chlorofluorocarbon into the top of a coke-type direct melting furnace, or the upper, middle or lower part of the furnace, or indirectly providing a steam generator by utilizing the exhaust heat of the furnace for vaporization. 5. A method of directly injecting chlorofluorocarbon into a molten liquid of molten metal or slag of a coke type direct melting furnace or a gasification melting furnace, or blowing a chlorofluorocarbon gas evaporated by a chlorofluorocarbon evaporator, How to vaporize or decompose chlorofluorocarbon