JPH09273727A - Organic halogen compound decomposition method - Google Patents

Abstract

(57) Abstract: Provided is a method for decomposing an organohalogen compound, which is capable of efficiently decomposing a large amount of an organohalogen compound without generating a harmful reaction product. A method for thermally decomposing a flame-retardant organic halogen compound such as Freon or Halon, which comprises maintaining the organic halogen compound and water vapor at a high temperature by burning an added combustion improver and a high-concentration oxygen gas. Decomposes into carbon dioxide and hydrogen halides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of decomposing organic halogen compounds such as CFCs and halon gases, which is capable of efficiently decomposing.

[0002]

2. Description of the Related Art Trichlorofluoromethane (CCl
CFCs such as ₃ F) or organic halogen compounds typified by halon gases such as trichlorobromomethane (CCl ₃ Br) have excellent chemical stability, and therefore, solvents and refrigeration equipment in production plants such as integrated circuits It has been widely used as a cooling medium and the like. However, organic halogen compounds that have volatilized in the atmosphere destroy the ozone layer,
Decomposition treatment is an important issue because it produces carcinogenic substances and seriously affects the global environment. As a method for decomposing such an organic halogen compound,
A combustion method in which an auxiliary fuel is added using air to burn an organic halogen compound, and a plasma reaction method in which an organic halogen compound is decomposed in high-temperature plasma are known. For example, as an example of the above-mentioned plasma reaction method, in Japanese Patent Laid-Open No. 3-90172, a carrier gas is introduced into a liquid organic halogen compound to cause bubbling so that the carrier gas contains the organic halogen compound, and Bubbling by introducing a carrier gas into the carrier gas, water is contained in the carrier gas, a carrier gas containing this organic halogen compound and water is mixed, and the mixed carrier gas is introduced into plasma. A method for decomposing an organic halogen compound by a reaction method is described.

[0003]

However, since the above conventional combustion method uses air, nitrogen oxides are generated, high temperature retention failure occurs, oxygen concentration is lowered, and dioxins are generated. The environment is polluted. Furthermore, the required amount of heavy oil, propane gas, etc. used as a combustion improver fluctuates, and the temperature maintenance is unstable, so it is necessary to add more burner than necessary, the amount of exhaust gas is large, and the decomposition of organic halogen compounds There was a problem of low efficiency. Further, the above-mentioned Japanese Patent Laid-Open No. 3-90172
The above-mentioned plasma reaction method as described in Japanese Patent Laid-Open Publication No. 2002-96240 is not general because it uses a high temperature plasma technology that is not widely used for waste treatment, although it has a small amount of exhaust gas, is easy to operate, and has a high treatment effect. There was a problem. The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a method for decomposing an organohalogen compound capable of decomposing a large amount and efficiently of an organohalogen compound without generating a harmful reaction product. To aim.

[0004]

According to the present invention, there is provided a semiconductor device comprising:
The method for decomposing an organic halogen compound described above is a method for thermally decomposing a flame-retardant organic halogen compound such as CFCs or halon, wherein the organic halogen compound and water vapor are added by burning an added combustion improver and a high concentration oxygen gas. Keep at high temperature and decompose into carbon dioxide and hydrogen halide. The method for decomposing an organohalogen compound according to claim 2 is a method for decomposing a combustible organohalogen compound such as CFCs or halons, in which a high concentration oxygen gas is added to the organohalogen compound and water vapor for combustion. Keep at high temperature and decompose into carbon dioxide and hydrogen halide. The method for decomposing an organohalogen compound according to claim 3 is the method for decomposing an organohalogen compound according to claim 1 or 2, wherein the high temperature state is 80
The temperature range is 0 ° C to 1600 ° C.

The organohalogen compound is obtained by substituting one or more halogen elements (F, Cl, Br, I) for a hydrogen atom in a hydrocarbon containing C, H, and optionally O and / or N. A hydrocarbon derivative. Further, the flame-retardant organic halogen compound means an organic halogen compound which does not generate a combustible gas such as hydrogen by the reaction with water vapor or water, for example, has one carbon atom in the molecule. The combustible organic halogen compound means, for example, an organic halogenated carbon or a carbonized organic halogenated carbon in which the number of carbon atoms in the molecule is 2 or more so that a combustible gas such as hydrogen is generated by the reaction with water vapor or water. It means hydrogen. The combustion improver refers to flammable substances such as heavy oil, kerosene, propane gas, city gas, and blast furnace gas. The high-concentration oxygen gas refers to oxygen gas having a concentration of about 90% by volume or more, which is obtained by treating air with a pressure swing adsorption (PSA) method or the like. Here, as the concentration of oxygen gas becomes higher, the burner or combustible organic halogen compound is efficiently oxidized and burned, and the high temperature required for decomposition of the organic halogen compound in the presence of a smaller amount of combustible material. The state can be maintained. High temperature is 800 ℃
When it is lower, the efficiency of the decomposition reaction of the organohalogen compound decreases. Further, if the temperature in the high temperature state is higher than 1600 ° C., harmful substances such as nitrogen oxides are generated and the durability of the reaction vessel used for the decomposition reaction is deteriorated, which is not preferable.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Next, referring to the attached drawings, an embodiment in which the present invention is embodied will be described to provide an understanding of the present invention. Here, FIG. 1 is a configuration diagram of an organic halogen compound decomposing facility 10 to which an organic halogen compound decomposing method according to a first embodiment of the present invention is applied. As shown in FIG. 1, an organic halogen compound decomposing facility 10 includes a combustion furnace including an oxygen burner 28 for mixing and burning an organic halogen compound, water vapor, a combustion improver, and a high concentration oxygen gas (hereinafter simply referred to as oxygen gas). 11 and a cooling can 12 which is disposed below the combustion furnace 11 and into which combustion exhaust gas is blown. The combustion furnace 11 is a substantially cylindrical reaction vessel lined with a refractory material such as refractory brick or amorphous refractory material.
In order to supply the upper portion of the combustion furnace 11 with trichlorofluoromethane (CCl ₃ F), which is an example of a flame-retardant organic halogen compound, steam, city gas which is an example of a combustion improver, and oxygen gas, respectively. The organic halogen compound supply pipe 14, the oxygen gas supply pipe 15, the steam supply pipe 16, and the oxygen burner 28 having the combustion improver supply pipe 17 are arranged, and an organohalogen compound supply control valve for controlling the respective supply amounts. 20, oxygen gas supply control valves 21, 2
1a, steam supply control valve 22 and combustion improver supply control valve 23
Is provided. As shown in FIG. 1, the oxygen gas and the water vapor are supplied not only from the central portion of the furnace top of the combustion furnace 11 but also from the peripheral portion thereof, and the mixed state of the gas in the combustion furnace 11, the temperature, and the decomposition reaction. Each quantity ratio can be adjusted according to the speed or the like. The lower portion of the combustion furnace 11 is reduced in diameter downward so that the combustion exhaust gas is discharged from the lower end portion. The cooling can 12 is filled with a cooling absorption liquid 27 for contacting with the combustion exhaust gas to cool it, and the combustion exhaust gas after cooling absorption is discharged from the exhaust hole 13 in the upper part of the cooling can 12.

Next, a method for decomposing an organic halogen compound according to the first embodiment of the present invention using the organic halogen compound decomposing facility 10 will be described below. First, city gas and oxygen gas are fed into the combustion furnace 11 through the combustion improver supply pipe 17 and the oxygen gas supply pipe 15, respectively, and the oxygen burner 28 is supplied.
And the temperature inside the combustion furnace 11 is raised to about 1200 ° C. When the temperature of the combustion furnace 11 is raised, the fuel such as city gas may be burned using air without using oxygen gas alone. Then, steam or liquid water and trichlorofluoromethane are supplied to the combustion furnace 11. At this time, trichlorofluoromethane, steam,
The supply rates of city gas and oxygen gas to the combustion furnace 11 are 50 kg / h, 24 Nm ³ / h, 60 Nm ³ / h, and
It was set to 160 Nm ³ / h. The concentration of oxygen gas at this temperature is about 5 with respect to the total volume of the substances fed into the combustion furnace 11.
57%, which is 0% or more, and the temperature in the combustion furnace 11 is 1
It was maintained at 200 to 1300 ° C.

Here, trichlorofluoromethane (CC
l ₃ F) reacts with water vapor as shown in the following reaction formula, is decomposed into carbon dioxide (CO ₂ ), hydrogen chloride (HCl), and hydrogen fluoride (HF), and contains these gases. It becomes combustion exhaust gas. CCl ₃ F + 2H ₂ O → CO ₂ + 3HCl + HF In this way, when decomposing only with steam or water such as Cl ₃ F, CCl ₂ F ₂ , CClF ₃ or CCl ₄ , flammability that becomes a heat source of hydrogen etc. When treating an organic halogen compound that does not generate gas, it is necessary to add a necessary amount of a combustion improver such as kerosene or city gas in advance. In some cases, the heat generated by the waste lubricating oil, which is generally mixed with trichlorofluoromethane (CCl ₃ F) as waste, is sufficient. On the other hand, in the case of an organic halogen compound such as trichlorotrifluoroethane (C ₂ Cl ₃ F ₃ ) shown in the following reaction formula, which generates flammable hydrogen gas by reaction with water and has a high calorific value, The amount of the combustion improver added may be relatively small. C ₂ Cl ₃ F ₃ + 4H ₂ O → 2CO ₂ + 3HCl + 3H
F + H ₂

As an organic halogen compound having such a high calorific value, trichlorotrifluoroethane (C ₂ C
l ₃ F ₃₎ that is, in addition to the _{C 2 F 3 Cl 3 (CFC113} ), C 2 F 4 Cl 2 (CFC114), C 2 F 5 Cl
(CFC115), C ₂ HF ₃ Cl ₂ (HCFC12
3), C ₂ HF ₄ Cl (HCFC124), CF ₂ Cl
₂ + C ₂ H ₄ F ₂ (R500) and the like include an organic halogen compound having 2 or more carbon atoms in the molecular formula, or an organic halogen compound containing a hydrogen element. Also, the addition of water vapor suppresses the generation of Cl ₂ by the reaction of H ₂ O + Cl ₂ → 2HCl + 1 / 2O ₂ , and therefore has the function of increasing the conversion efficiency to hydrogen halide. The combustion exhaust gas after this decomposition reaction is brought into contact with the cooling absorption liquid 27 arranged in the cooling can 12, and hydrogen halide (HCl, HF)
Captures some of the gas. Then, the cooled combustion exhaust gas discharged from the exhaust hole 13 of the cooling can 12 is fed into an absorption tower (not shown), and the combustion exhaust gas is absorbed by an absorption liquid such as an aqueous potassium hydroxide solution or an aqueous sodium hydroxide solution. , HF), halogen (Cl ₂ , F ₂ )
Capture the gas of. Further, the cooling / absorbing liquid 27 can be neutralized in a neutralization tank (not shown) and the precipitate can be collected by a centrifuge, and the precipitate containing CaF ₂ as a main component can be reused if necessary. You can do it.

As described above, by combusting and decomposing the chlorofluorocarbon under a high oxygen concentration, the amount of flue gas when treating 1 kg of fluorocarbon could be ³ Nm ³ / kg. The amount of the combustion exhaust gas is about 20% of the amount of the combustion exhaust gas when the conventional air is used to decompose the oxygen gas at a concentration of 21% by volume. In addition, the addition of water (steam) suppresses the generation of halogen gas such as chlorine gas and fluorine gas, and lowers the temperature of the flame in the combustion furnace 11 to prevent the generation of harmful nitrogen oxides (NO _x ). It has become possible.

Next, an organic halogen compound decomposing method according to a second embodiment of the present invention using the organic halogen compound decomposing facility 10 will be described with reference to FIG. First, propane gas, which is an example of a combustion improver, and oxygen gas are fed into the combustion furnace 11 and ignited to raise the temperature in the combustion furnace 11 to about 1200 ° C. Then, such as chlorodifluoromethane (CHClF ₂ ) or the like, a CFC gas containing hydrogen atoms in the molecule or a mixed gas of two or more of these is supplied to the combustion furnace 11 as an organic halogen compound, and steam is supplied, The oxygen gas concentration was set to be about 16%. Then, in the flame of the combustion furnace 11 at about 1000 ° C., the organic halogen compound and water vapor react with each other to be decomposed into hydrogen chloride, hydrogen fluoride, carbon dioxide, and hydrogen gas, and the hydrogen gas immediately It is possible to maintain the temperature required for the decomposition reaction and continue the reaction without being oxidised and generating heat to require a combustion improver. The combustion exhaust gas after the decomposition comes into contact with the cooling absorption liquid 27 such as an aqueous solution of potassium hydroxide that also serves as an absorption liquid of hydrogen halide in the cooling can 12, and is discharged from the exhaust hole 13. In this way, without using a combustion improver
Since the decomposition reaction is continued, the generation of excessive combustion exhaust gas is suppressed, and the amount of nitrogen gas is small or absent compared to the conventional case where air is used as the oxidant, so the generation of nitrogen oxides is prevented. can do.

Next, an organic halogen compound decomposing method according to a third embodiment of the present invention will be described. FIG. 2 is a configuration diagram of an organic halogen compound decomposing facility 18 to which an organic halogen compound decomposing method according to a third embodiment of the present invention is applied. The organic halogen compound decomposing equipment 18 is the same as the organic halogen compound decomposing equipment 10 used in the organic halogen compound decomposing method according to the first embodiment described above.
A control device 19 for controlling the organohalogen compound supply control valve 20, the steam supply control valve 22, the combustion improver supply control valve 23, and the oxygen gas supply control valves 21 and 21a, respectively.
Is added. Further, a thermometer 24 for measuring the temperature inside the combustion furnace 11 is arranged on the furnace wall of the combustion furnace 11, and a gas component analyzer for analyzing the components in the combustion exhaust gas is provided near the exhaust hole 13. 25 or a gas flow meter 26 is provided, and these measurement data are taken into the control device 19 as needed.

Next, an organic halogen compound decomposing method according to a third embodiment of the present invention using the organic halogen compound decomposing facility 18 will be described below. First, the control device 19 operates the auxiliary combustion agent supply control valve 23 and the oxygen gas supply control valves 21 and 21a to send propane gas and oxygen gas, which are examples of the auxiliary combustion agent, into the combustion furnace 11 and ignite them. The gas in the combustion furnace 11 to about 12
The temperature is raised to and maintained at 00 ° C. Then, the steam controlled by the controller 19 to a predetermined amount and trichlorotrifluoroethane, which is an example of an organic halogen compound, are used in the combustion furnace 11
To supply. Then, the thermometer 24 and the gas component analyzer 25
Alternatively, while monitoring the respective measurement data from the gas flow meter 26, when the temperature inside the combustion furnace 11 measured by the thermometer 24 falls below 1000 ° C., for example, it is supplied as a combustion improver. The amount of propane gas supplied can be increased.

Further, when the temperature in the furnace exceeds 1300 ° C., the supply amount of oxygen gas or the supply amount of the combustion improver is reduced to set a predetermined temperature range, for example, 1000 ° C.
By controlling the temperature in the range of 1300 ° C, the amount of dioxin, etc. that depends on the oxygen concentration, residence time, and the degree of mixing of fuel and oxygen in the combustion reaction is controlled to minimize the generation of unburned harmful substances. You can Here, the residence time is, for example, a time obtained by dividing the supply rate of each supply substance by the effective volume in the combustion reaction. On the other hand, the ratio of the flow rate of the combustion exhaust gas discharged from the exhaust hole 13 and the concentration of hydrogen halide such as hydrogen chloride in the combustion exhaust gas to the supply amount of trichlorotrifluoroethane supplied to the combustion furnace 11 is measured. The decomposition efficiency can be calculated by taking Then, a control procedure obtained by aggregating past operation results or experimental results is input into the control device 19 in advance, and the decomposition efficiency is used as an index, and the oxygen gas supply amount, the steam supply amount, the combustion supporting agent supply amount, etc. Can be adjusted to control the decomposition reaction of trichlorotrifluoroethane. Therefore, the decomposition reaction by combustion is always carried out in the range of an appropriate oxygen amount, so that the amount of the combustion exhaust gas does not become excessive, and the cost of the cleaning treatment of the combustion exhaust gas in the post process can be reduced.

The embodiment of the present invention has been described above.
The present invention is not limited to such an embodiment, and all changes in conditions that do not depart from the gist are within the scope of the present invention. For example, although the case where only one kind of the organic halogen compound is used is shown in this embodiment mode, a mixture containing a plurality of kinds of organic halogen compounds and a solvent of the organic halogen compound, for example, acetone, methanol, or the like at high temperature is used. It can also be treated to decompose organohalogen compounds.

[0016]

In the method for decomposing an organic halogen compound according to claims 1 and 3, the flame-retardant organic halogen compound and water vapor are maintained in a high temperature state by combustion of the added burner and high concentration oxygen gas, As it decomposes into carbon dioxide and hydrogen halide, it burns the combustion improver under high concentration of oxygen and uses the heat of combustion generated at this time as a heat source to obtain a high temperature state to efficiently react the organic halogen compound with water vapor. The organic halogen compound can be efficiently decomposed, and the presence of water vapor suppresses the generation of halogen gas. Further, since the combustion improver is burned under a high concentration oxygen gas, it is possible to prevent the production of harmful substances such as nitrogen oxides. In the method for decomposing an organohalogen compound according to claims 2 and 3, high-concentration oxygen gas is added to a combustible organohalogen compound and water vapor for combustion, and the mixture is kept at a high temperature to decompose into carbon dioxide and hydrogen halide. Therefore, the decomposition reaction can be maintained by the heat generation of the combustible organic halogen compound itself, the generation of nitrogen oxides can be suppressed, and the organic halogen compound can be efficiently decomposed without using a combustion improver. You can Therefore, the amount of combustion exhaust gas can be suppressed to a necessary minimum, and the processing cost of the combustion improver can be reduced. In particular, in the method for decomposing an organohalogen compound according to claim 3, since the high temperature state is within a specific temperature range, the efficiency of the decomposition reaction can be maintained more appropriately and the generation of harmful substances such as nitrogen oxides and dioxins is suppressed. To be done.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an organohalogen compound decomposing facility to which an organohalogen compound decomposing method according to first and second embodiments of the present invention is applied.

FIG. 2 is a configuration diagram of an organic halogen compound decomposing facility to which an organic halogen compound decomposing method according to a third embodiment of the present invention is applied.

[Explanation of symbols]

10 Organohalogen Compound Decomposing Facility 11 Combustion Furnace 12 Cooling Can 13 Exhaust Hole 14 Organohalogen Compound Supply Pipe 15 Oxygen Gas Supply Pipe 16 Water Vapor Supply Pipe 17 Combustor Supply Pipe 18 Organohalogen Compound Decomposing Facility 19 Control Device 20 Organohalogen Compound Supply Control Valve 21 Oxygen gas supply control valve 21a Oxygen gas supply control valve a 22 Steam supply control valve 23 Combustor supply control valve 24 Thermometer 25 Gas component analyzer 26 Gas flow meter 27 Cooling absorption liquid 28 Oxygen burner

Front page continued (72) Inventor Shigeru Mitarai 46 59 Nakahara, Tobata-ku, Kitakyushu City, Fukuoka Prefecture 59 Nittetsu Plant Design Co., Ltd.

Claims (3)

[Claims] 1. A method for thermally decomposing a flame-retardant organic halogen compound such as Freon or Halon, wherein the organic halogen compound and water vapor are kept at a high temperature by combustion of an added combustion improver and a high concentration oxygen gas. And decomposition into carbon dioxide and hydrogen halide. 2. A method for thermally decomposing a combustible organic halogen compound such as Freon or Halon, which comprises adding a high concentration oxygen gas to the organic halogen compound and water vapor and burning the mixture to maintain a high temperature. A method for decomposing an organic halogen compound, which comprises decomposing into carbon and hydrogen halide. 3. The method for decomposing an organohalogen compound according to claim 1, wherein the high temperature state is in a temperature range of 800 ° C. to 1600 ° C.