KR20010106040A - Method for abatement and treatment of CFC or PFC by direct-current thermal plasma - Google Patents

Abstract

A method and apparatus (110) for assessing the visibility of differences between two input signal sequences, e.g., image sequences is disclosed. The apparatus comprises a perceptual metric generator (112) having an input signal processing section (210), a luminance processing section (220), a chrominance processing section (230) and a perceptual metric generating section (240, 250, 260).

Description

Method for abatement and treatment of CFC or PFC by direct-current thermal plasma}

The present invention relates to a method for decomposing and treating chlorofluorocarbons (CFCs) or perfluoro compounds (PFCs), which are global warming and ozone depleting substances, using DC thermal plasma. Generating hydrogen chloride, hydrogen fluoride, carbon monoxide, carbon dioxide, or water by passing a mixed gas of CFC, Chlorofluoro carbon) or perfluoride (PFC) and perfluoro compounds through a direct-current thermal plasma space (step 1), the step A method for decomposing and treating CFCs or PFCs, comprising a quenching step (step 2) of the product obtained from step 1 and a detoxification step (step 3) of the quenching product obtained from step 2 above.

CFCs and PFCs have very high global warming contributions. One molecule of the compound has a global warming contribution of several thousand to tens of thousands compared to carbon dioxide (CO ₂ ), and the global warming rate by CFC is second only to carbon dioxide (55). Occupies 24 (see Table 1). In addition, CFCs not only affect the warming effect but also affect the ozone layer destruction. Freon (CCl ₃ F, CCl ₂ F ₂ , CClF ₃ , CHCl ₂ F) used in refrigerators and aerosols is released into the atmosphere and reaches the stratosphere. It is decomposed by high-energy sunlight to release chlorine atoms, and the chlorine atoms and chlorine oxide radicals (ClO) rapidly break down and cause widespread dispersion in the stratosphere to destroy the ozone layer. As can be seen in Table 1, the global warming is a particular freon caused by staying in the atmosphere in large quantities for as little as 50 to 50,000 years, the problem is more serious, if you continue to use the existing freons 3 to 7 every year Increased concentrations have been reported to be very serious in 2030, with global mean concentrations ranging from 0.9 to 3.5 ppb for CFC12. Table 1 below shows the types of compounds belonging to CFCs and PFCs, their use and global warming.

Types, uses and global warming of CFCs and PFCs Kinds Substance Usage Global warming degree (CO ₂ = 1) Period of stay in air (years) CFC Compound CFC 11 (CFCl ₃ ) Trichlorofluoromethane Refrigerant Foaming Agent 4,000-11,700 50 to 1,700 CFC 12 (CCl ₂ F ₂ ) Dichlorodifluoromethane Blowing agent CFC 113 (C ₂ Cl ₃ F ₃ ) 1,1,2-trichlorotrifluoro-ethane detergent PFC Compound CF ₄ Tetrafluoromethane Semiconductor etching 6,500 740-50,000 C ₂ F ₆ Hexafluoroethane Semiconductor etching 9,200 SF ₆ Sulfur hexafluoride Semiconductor Etch Insulation 23,900

With the adoption of the Montreal Protocol, the response to Freon's environmental destruction is intensifying worldwide, and development of alternative materials for Freon is underway. Currently, the production of CFCs in developed countries has ceased, and CFCs used as refrigerants and blowing agents It is being replaced by HFC, HCFC and hydrocarbons. However, in the case of cleaners such as CFC113, no suitable alternatives have been developed and international agreements allow developing countries to use CFCs by 2005. Therefore, it is very urgent to develop a method for safely disposing of CFCs, PFCs such as CFC113, and additionally regulated HCFCs for disposal.

Currently known CFC decomposition methods include combustion and thermal decomposition methods, catalytic methods, reagent methods, supercritical water methods, and plasma methods. Among these, combustion and pyrolysis are methods for combusting CFCs in a petroleum-based combustion apparatus, and according to the types of CFCs, complete decomposition is impossible and there is a problem of identifying byproducts present in the exhaust gas.

Catalysis is a method in which a gas containing CFCs and water vapor is continuously passed on a solid catalyst at atmospheric pressure to be decomposed. For example, 1,1,2-trifluoroethane (C ₂ Cl ₃ F _3, hereinafter abbreviated as “CFC 113”) and water vapor are mixed in vapor form and brought into contact with an H-type zeolite catalyst at high temperature to form CFC 113. Decomposition produces hydrogen chloride, hydrogen fluoride, carbon monoxide and carbon dioxide. However, the catalyst method is important in the durability of the catalyst in a continuous reaction, and in most cases a constant amount of reaction is not economical because it does not maintain the normal activity of the catalyst for more than 200 hours and loses its role as a catalyst.

Reagent decomposition is a method of reductively decomposing CFCs by reacting sodium naphthalenide (Na ⁺ Naph ⁻ ) with CFCs in a gas or liquid state dissolved in an organic solvent to produce NaCl and NaF. When this method is commercialized, it consumes an excess of reagents, which leads to high maintenance costs and environmental hazards of the reaction products.

On the other hand, as a method of decomposing PFC, a method of carrying out the above method while using a combustion / pyrolysis method and a catalyst layer is known. In the case of combustion and pyrolysis, there is not enough temperature to decompose PFC, which is a stable material, so that PFC cannot be completely decomposed, and because it uses flammable gas, there is a high risk of fire when used in actual plants. When the catalyst layer is used in the combustion and pyrolysis method, an expensive catalyst that is almost dependent on imports is used. However, the replacement cycle of the catalyst is very short, which is not practical because of high operating costs.

As an alternative to the conventional methods, methods for decomposing CFCs and PFCs using plasma have been studied. As a method for decomposing CFCs and PFCs using low-temperature plasmas (non-equilibrium plasmas), radio frequency (RF), microwave, corona, and the like are used. As a result of decomposing CFC and PFC using this method, the decomposition rate is over 95 irrespective of the method. Among these methods, when plasma is generated by using radio waves and microwaves, it must be operated at low pressure (tens of torr) and corona discharge. In this case, there is a disadvantage that the plasma in the reactor is not uniform. In addition, the method using a low-temperature plasma has a problem that the processing capacity is limited because the amount of CFC and PFC that can be treated in common is less than ˜10 ⁻² L / min.

Accordingly, the present inventors have tried to solve the above problems, and as a result, the large-scale decomposition of CFCs or PFCs using DC thermal plasma with high decomposition rate, the gases generated by the decomposition of CFCs or PFCs can be used as a renewable resource, neutralization treatment or air The present invention has been completed by finding that it can be converted into hydrogen chloride, hydrogen fluoride, carbon monoxide, or carbon dioxide, which can be easily treated such as being released in the air.

It is an object of the present invention to provide a method of decomposing CFCs or PFCs using a direct-current thermal plasma and converting them into materials that are easy to process and less likely to be recontaminated.

Figure 1a schematically shows a decomposition process of chlorofluorocarbons (CFC) by direct thermal plasma,

Figure 1b schematically shows a decomposition process of PFC (Perfluoro compounds) by direct thermal plasma,

2 shows the conversion rate of carbon monoxide and carbon dioxide of CFC113 according to the change in the flow rate of oxygen when the flow rate ratio of CFC 113 (C ₂ Cl ₃ F ₃ ) and hydrogen is 1: 3,

3 shows the carbon monoxide conversion rate of CFC113 according to the change in the flow rate of hydrogen when the flow rate ratio of CFC 113 and oxygen is 1: 2, 1: 1.5, and 1: 1,

4 shows the conversion rate of carbon monoxide and carbon dioxide of CFC113 according to the power change when the flow rate ratio of CFC 113, oxygen and hydrogen is 1: 1: 3,

5 shows the carbon monoxide and carbon dioxide conversion of CFC113 according to the change of the total flow rate when the flow rate ratio of CFC 113, oxygen and hydrogen is 1: 1: 3,

Figure 6 shows the carbon monoxide conversion rate of CFC 113 according to the inner diameter of the cooling tube,

Figure 7 shows the decomposition rate of CF ₄ according to the flow rate of CF _4,

8 shows the decomposition rate of CF ₄ according to the change in oxygen flow rate,

9 shows the decomposition rate of CF ₄ according to the hydrogen flow rate change,

10 shows the decomposition rate of CF ₄ according to the plasma power change,

11 shows the decomposition rate of CF ₄ according to the flow rate of oxygen when hydrogen and oxygen are mixed and added.

In order to achieve the above object, the present invention provides a decomposition and treatment method of a CFC or PFC using a direct-current thermal plasma.

CFCs that can be treated by the method of the present invention include CFC 11 (CFCl ₃ ), CFC 12 (CCl ₂ F ₂ ) or CFC 113 (C ₂ Cl ₃ F ₃ ), etc., PFC is CF ₄ , C ₂ F ₆ , NF ₃ or SF ₆ and the like.

Hereinafter, the present invention will be described in detail.

Specifically, the present invention

1) generating hydrogen chloride, hydrogen fluoride, carbon monoxide, carbon dioxide, or water by passing a mixed gas of chlorofluorocarbon (CFC) or perfluoride (PFC) and perfluoro compounds (PFC) into a direct thermal plasma space; Step 1),

2) quenching of the product obtained from step 1 (step 2) and

3) The decomposition and treatment method of CFC or PFC which consists of the detoxification step (step 3) of the quench product obtained from the said step 2.

Step 1 of the present invention is a step of decomposing CFCs or PFCs by direct thermal plasma, and simultaneously reacting chemical species such as atoms, ions, excitons, and radicals of the decomposed CFCs or PFCs with oxygen, hydrogen, and / or water vapor. Plasma is generated using argon gas. In the direct thermal plasma, an arc is generated by the electrical energy of the cathode and the anode, and a high temperature plasma of about 10,000 K is generated by the argon gas. Argon is generally the most widely used gas for generating plasma. Since it is a group 8 element, it is easy to emit electrons with relatively little energy, and inert gas has little effect on chemical reaction. Argon is the most abundant in the atmosphere and is easy to get and cheap. The high temperature plasma generated by argon has a high energy so that the compounds in the plasma are decomposed into species such as atoms, ions, excitation molecules and radicals. In addition, the strong ultraviolet light generated in the plasma further promotes dissociation of CFCs and PFCs that pass through the plasma. That is, CFCs or PFCs that pass through the plasma are uniformly decomposed at a very fast decomposition rate due to the interaction between pyrolysis and photolysis by the plasma.

The preferred DC thermal plasma has a temperature of 1,000 K to 10,000 K, and a thermal plasma temperature of about 10,000 K is sufficient to decompose the molecules to be decomposed, so a DC thermal plasma power of about 5 kW is sufficient. The temperature of the plasma rises only a few tens or even hundreds of K, which does not significantly affect the decomposition rate of CFCs and PFCs.

Air, nitrogen, hydrogen, oxygen, and water vapor to react with atoms, ions, excitons, radicals, and the like of CFCs or PFCs decomposed by the direct current thermal plasma are injected into the plasma alone or in the form of a mixed gas. When decomposing CFC 113, it is preferable that the flow rate ratio (mol / s) of the mixed gas CFC 113: oxygen: hydrogen injected into the plasma is 1: 1: 3 to 1: 3: 3 (see Table 2). 113 decomposes over 99.99. The decomposition rate () of CFC in the thermal plasma was defined as follows based on the fact that no new CFC compound is produced upon decomposition of CFC 113. In Equation 1, [x] represents the number of moles of x material.

On the other hand, when decomposing CFC by adding oxygen into the plasma as a reaction gas, carbon dioxide (CO ₂ ) and carbon monoxide (CO) are produced competitively. Carbon monoxide, unlike carbon dioxide, is a compound in an unstable state, and can be used as a fuel because of its excellent bond with oxygen. The synthesis gas of carbon monoxide and hydrogen can also be used for methanol synthesis. In order to decompose CFC113 more than 99.99 and to have a carbon monoxide conversion ratio of 1 which can be used as a regeneration resource in the decomposition products, it is preferable that the flow ratio of the mixed gas CFC 113: oxygen: hydrogen is 1: 1: 3. In a reducing atmosphere in which hydrogen is excessively added, CFCs are inhibited from being converted to carbon dioxide by hydrogen, and water is also generated by reaction of hydrogen with some oxygen not converted to carbon dioxide. The conversion rate of carbon monoxide in the decomposition product is defined as follows. In Equation 2, [x] represents the number of moles of x material.

On the other hand, CF ₄ is difficult to decompose into the most stable compound in PFC, but when mixed with oxygen or hydrogen and injected into the plasma, the decomposition rate of CF ₄ increases as the amount of added oxygen or hydrogen increases, and hydrogen is added rather than adding oxygen. The addition rate is further better. When hydrogen is injected alone into the reactor body, PFC: hydrogen is preferably injected at a flow rate ratio (l / min) of 1: 1 to 1: 4. When CF ₄ is added to the plasma together with oxygen and hydrogen, the decomposition rate is higher than that of adding oxygen alone, but lower than that of adding hydrogen alone. This is because hydrogen and oxygen combine with the decomposed CF ₄ and bond between the two atoms dissociated in the plasma.

Step 2 of the present invention is a step of quenching the high-temperature product gas in step 1, the species, such as atoms, ions, radicals, and oxygen, hydrogen or water vapor of the CFC or PFC decomposed in step 1 while leaving the plasma center They have a high cooling rate and recombine with each other to produce thermodynamically stable hot gases such as hydrogen chloride, hydrogen fluoride, carbon monoxide and carbon dioxide. The produced gas is quenched in a temperature range around 300 ° C. where harmful substances are produced and released into the gas at room temperature.

Step 3 of the present invention is a step of detoxifying the gas released in step 2, wherein the generated HCl and HF are neutralized by reacting with a basic substance. In this case, the basic material may be an aqueous sodium hydroxide solution, an aqueous calcium oxide solution, or the like. The carbon monoxide produced can also be reburned or used for fuel and methanol synthesis, and carbon dioxide is released into the atmosphere.

An example of a CFC or PFC decomposition and processing apparatus is shown in FIG. 1A and FIG. 1B . This apparatus mainly consists of a plasma generating section, a decomposition and reaction section, a quenching section and a harmless processing section.

The plasma generating unit is composed of an anode nozzle and a cathode rod which are cooled in water, and generates plasma jets by flowing argon gas to generate plasma between the anodes.

The decomposition and reaction part consists of a stainless steel double tube which is water-cooled and is mixed with oxygen, hydrogen or / and steam and argon which is a plasma generating gas as a gas for the reaction. The reaction gas, or CFC or PFC, may be injected through an injection hole provided between the plasma generator and the decomposition and reaction unit, or may be directly injected between the anode and the cathode of the plasma generator. In this case, the CFC or PFC to be decomposed may be directly mixed between the positive electrode and the negative electrode by mixing with the reaction gas.

The quench section is a double cooling tube made of copper and cools by flowing water between the double cooling tubes. In the dual cooling tube used in the present invention, the smaller the inner diameter, the higher the carbon monoxide conversion rate of the CFC. This is because as the inner diameter of the cooling tube is reduced, the heat is quickly cooled by smooth heat exchange.

The gas cooled in the quenching unit is preferably neutralized with an aqueous sodium hydroxide solution and an aqueous calcium oxide solution, and then subjected to detoxification by forced exhaust and discharge using an aspirator.

Hereinafter, the present invention will be described in more detail with reference to Examples.

However, the following examples are merely to illustrate the content of the present invention is not limited to the scope of the present invention.

Example 1 Degradation of CFC 113 by Thermal Plasma 1

Generate a plasma of about 10,000 K at a power of 5 kW and an argon flow rate of 10 l / min, and 1.5 × 10 ^-4 mol / s, 1.5 × 10 ^-4 mol / s, and 4.5 × 10 at room temperature Injected at a flow rate of ^-4 mol / s. The generated gas was neutralized by successively passing through a 10 mM sodium hydroxide solution and a 10 mM calcium oxide solution, and quantitatively analyzed the decomposition rate of CFC 113 using gas chromatography.

Under these conditions, CFC 113 decomposed over 99.99.

Example 2 Decomposition of CFC 113 by Thermal Plasma 2

Example 1 except that CFC 113, oxygen, and hydrogen were mixed and injected into the plasma at a flow rate of 1.5 × 10 ⁻⁴ mol / s, 2.25 × 10 ⁻⁴ mol / s, and 4.5 × 10 ⁻⁴ mol / s, respectively. CFC 113 was decomposed and neutralized in the same manner.

Under these conditions, CFC 113 decomposed over 99.99.

Example 3 Decomposition of CFC 113 by Thermal Plasma 3

Example 1 except that CFC 113, oxygen, and hydrogen were injected into the plasma by mixing at a flow rate of 1.5 × 10 ⁻⁴ mol / s, 3.0 × 10 ⁻⁴ mol / s, and 4.5 × 10 ⁻⁴ mol / s, respectively. CFC 113 was decomposed and neutralized in the same manner.

Under these conditions, CFC 113 decomposed over 99.99.

Example 4 Degradation Rate of CFC 113 by Thermal Plasma 4

Example 1 except that CFC 113, oxygen, and hydrogen were injected into the plasma by mixing at a flow rate of 1.5 × 10 ⁻⁴ mol / s, 4.5 × 10 ⁻⁴ mol / s, and 4.5 × 10 ⁻⁴ mol / s, respectively. CFC 113 was decomposed and neutralized in the same manner.

Under these conditions, CFC 113 decomposed over 99.99.

The decomposition rate of CFC 113 according to the flow rate ratio of CFC 113, hydrogen and oxygen is shown in Table 2 below.

Degradation Rate of CFC 113 by Thermal Plasma Example Flow rate [mol / s] Decomposition rate [] CFC 113 Oxygen Hydrogen One 1.5 × 10 ^-4 1.5 × 10 ^-4 4.5 × 10 ^-4 99.991 2 1.5 × 10 ^-4 2.25 × 10 ^-4 4.5 × 10 ^-4 99.995 3 1.5 × 10 ^-4 3.0 × 10 ^-4 4.5 × 10 ^-4 99.992 4 1.5 × 10 ^-4 4.5 × 10 ^-4 4.5 × 10 ^-4 99.990

As a result of quantitative analysis under each stoichiometric condition, a high decomposition rate of 99.99 or more was obtained under all conditions shown in Table 2 above.

Example 5 Decomposition of CFC 113 with Oxygen Flow Rate Change

The carbon monoxide conversion was measured by changing the flow rate ratio (mol / s) of CFC 113: oxygen: hydrogen (mol / s) from 1: 1: 3 to 1: 3: 3 at a plasma power of 5 kW and a plasma generating gas of 10 l / min. 2 is shown.

As shown in FIG. 2 , when the oxygen flow ratio is 1 for the CFC 113 flow rate, mainly carbon monoxide is generated, and as the oxygen ratio increases, the conversion to carbon monoxide decreases so that the CFC 113 is CFC 113: oxygen: hydrogen = 1: 3: 3. It can be seen that it is converted to carbon dioxide without producing carbon monoxide. As a result of the experiment, it can be seen that in order to generate carbon monoxide that can be used as a renewable resource, it is most preferable to inject the CFC 113: oxygen: hydrogen so that the flow rate ratio is about 1: 1: 3.

Comparing the experimental results with the results calculated using ChemSage 3.01, which is a commercial software, the decomposition and formation trends according to the temperature were compared. Esau did not match. The reason for this is that the recombination of each element, ion, molecule, and radicals decomposed at high temperature occurs rapidly and passes through a narrow cooling tube, which is a quenching portion, and is rapidly cooled. Therefore, it can be seen that decomposition products at a temperature of about 1000 K do not have a continuous equilibrium relationship from high temperature to room temperature, and may exist at room temperature as a substance produced by decomposition.

Example 6 Decomposition of CFC 113 with Change of Hydrogen Flow Rate 1

The CFC 113: oxygen flow rate ratio introduced into the plasma is fixed at 1: 1 and the ratio of hydrogen is changed to 3 to 3.75 (4.5 × 10 ^-4 mol / s to 5.4 × 10 ^-4 mol / s) times, thereby improving the carbon monoxide conversion rate. was measured. the results are shown in Fig.

When CFC 113: Oxygen = 1: 1, carbon monoxide conversion increases with increasing hydrogen ratio, and at 5.4 × 10 ^-4 mol / s flow rate with hydrogen flow ratio of 3.75 for CFC 113 flow rate, no carbon dioxide is produced and completely converted to carbon monoxide. It became. This is because the conversion to carbon dioxide is suppressed in the excess hydrogen reduction atmosphere, and a portion of oxygen that cannot be converted to carbon dioxide reacts with hydrogen to generate water. The difference from the results calculated using ChemSage 3.01 is considered to be the difference in cooling rate, and the equilibrium concentration near 1,000 K was similar to the experimental value.

Example 7 Decomposition of CFC 113 with Change of Hydrogen Flow Rate 2

The same procedure as in Example 6 was carried out except that the flow rate ratio of CFC 113: oxygen injected into the plasma was fixed at 1: 1.5.

As can be seen in Figure 3 , it can be seen that as the hydrogen increases under the above conditions, the carbon dioxide conversion increases and then the increase rate gradually decreases.

Example 8 Decomposition of CFC 113 with Change of Hydrogen Flow Rate 3

The same procedure as in Example 6 was carried out except that the flow rate ratio of CFC 113: oxygen injected into the plasma was fixed at 1: 2.

As can be seen in Figure 3 , the same results as in Example 7 were obtained under the above conditions.

Example 9 Decomposition of CFC 113 According to Power Variation

The carbon monoxide conversion was measured while fixing the ratio of the mixed gas to CFC 113: oxygen: hydrogen = 1: 1: 3 and changing the DC plasma power to 5-7 kW. The results are shown in FIG. 4 .

As can be seen in Figure 4 , even if the plasma power is increased the increase in the carbon monoxide conversion was shown to be minimal. This is thought to be because even if the plasma power continues to increase, the temperature of the plasma rises from about 10,000 K to only tens or hundreds of K and no large temperature change occurs. Therefore, it could be seen that if the injected molecules were kept above the decomposition temperature, they could be sufficiently decomposed at 5 kW of power.

Example 10 Decomposition of CFC 113 with Increasing Total Flow of Mixed Gas

Plasma power 5 kW, CFC113: Oxygen: Hydrogen Carbon monoxide was injected into the plasma while changing the flow rate of CFC 113 from 1.5 × 10 ^-4 mol / s to 3.0 × 10 ^-4 mol / s while maintaining a flow ratio of 1: 1: 3. measuring the conversion rate was the results are shown in Fig.

As the flow rate of the mixed gas injected into the plasma increases, the carbon monoxide conversion tends to decrease slightly. The reason for this is that when a large amount of mixed gas composed of CFC 113 and hydrogen, oxygen and argon is injected, the CFC 113 decomposition is an endothermic reaction, so the temperature drop is severe at the inlet inlet, and the plasma bulk temperature decreases, thereby decomposing CFC 113. It seems to be because it does not happen completely. Therefore, it can be seen that the smaller the amount of the mixed gas to be injected, the more complete decomposition occurs.

Example 11 Decomposition of CFC 113 According to Cooling Tube Inner Diameter

Plasma power 5kW, CFC113 flow rate 1.5 × 10 ^-4 mol / s, hydrogen flow rate 1.5 × 10 ^-4 mol / s while oxygen flow rate and three types of cooling tube diameter (4, 6, 8mm) Carbon monoxide conversion was measured and the results are shown in FIG. 6 . Since the cooling rate of the decomposition product varies according to the inner diameter of the cooling tube, the effect of this is examined.

As can be seen in Figure 6 , the total carbon monoxide conversion was slightly higher as the inner diameter of the cooling tube as a whole. Also, when CFC113: Oxygen: Hydrogen flow ratio is 1: 1: 3 and 4mm inner diameter cooling tube is used, the carbon monoxide conversion is almost 1, but as the inner diameter of the cooling tube increases and the amount of oxygen flowed into the plasma increases, Production increases sharply.

As shown in Example 6, when the concentration value of the decomposition product obtained in the experiment and the calculation result of ChemSage were compared, the concentration value of the product at room temperature was different due to the fast cooling rate. Rapid cooling with good heat exchange did not match the experimental and calculated values for the concentration of the cracked product.

The CFC decomposition conditions of Examples 1 to 11 according to the present invention are shown in Table 3 below.

CFC decomposition conditions Plasma input power 5 to 7 ㎾ Plasma generating gas Argon 10 ℓ / min flux CFC 113 (C ₂ Cl ₃ F ₃ ) 1.5 × 10 ^-4 mol / s to 3.0 × 10 ^-4 mol / s (1.69 g / min to 3.37 g / min) Oxygen 1.5 × 10 ^-4 mol / s to 6.0 × 10 ^-4 mol / s (0.2 L / min to 0.8 L / min) Hydrogen 4.5 × 10 ^-4 mol / s to 9.0 × 10 ^-4 mol / s (0.6 L / min to 1.2 L / min) Inner diameter of cooling tube 4mm, 6mm, 8mm

Example 12 CF ₄ CF according to flow rate change ₄ Decomposition of 1

In order to decompose CF ₄ , the most stable substance among PFCs, the flow rate of argon was fixed to 15 l / min at 6 kW and argon, and the inflow rate of CF ₄ was 0.15 l / min (1 compared to argon), 1.06 l / min (7), The decomposition rate of CF ₄ was determined by changing to 2.12 L / min (14). The results are shown in Fig.

The larger the amount of CF ₄ introduced into the plasma, the lower the decomposition rate. In other words, the lower the loading rate, the higher the decomposition rate.

Example 13 CF ₄ CF according to flow rate change ₄ Decomposition of 2

With the exception that the inlet for the plasma generating gas to 10ℓ / min and measuring the decomposition of the CF ₄ CF ₄ flow rate in the same manner as in Example 12, The results are shown in Fig.

As shown in FIG. 7 , the decomposition rate decreased as the amount of CF ₄ introduced into the plasma decreased, and the CF ₄ decomposition rate also decreased as the flow rate of argon decreased.

Example 14 CF According to Change of Oxygen Flow Rate ₄ Decomposition of 1

Plasma power 6kW, argon flow rate 15 l / min, CF ₄ flow rate 1 l / min were fixed and the decomposition rate of CF ₄ was measured while injecting oxygen at 0.5, 1, 1.5 l / min into the reaction gas, and the results are shown in FIG. 8 . It was.

In Example 13, when the CF ₄ flow rate 1.06 L / min was directly decomposed without adding oxygen, the decomposition rate of CF ₄ was about 0.27. However, in Example 14, when the oxygen was decomposed by adding 1.5 L / min, the decomposition rate was about. It was found that it increased to 0.38, and the decomposition rate increased with increasing amount of oxygen at a constant CF ₄ flow rate.

Example 15 CF According to Change in Oxygen Flow Rate ₄ Decomposition of 2

The decomposition rate of CF ₄ was measured in the same manner as in Example 14 except that the plasma power was 9 kW, and the results are shown in FIG. 8 together with the results of Example 14.

When oxygen was injected into the reaction gas to decompose CF ₄ , the decomposition rate of CF ₄ also increased when the flow rate of oxygen increased regardless of plasma power.

Example 16 CF According to Hydrogen Flow Rate Change ₄ Decomposition of 1

The decomposition rate of CF ₄ was measured by fixing a plasma power of 6 kW, an argon flow rate of 15 l / min, and a CF ₄ flow rate of 1 l / min, and increasing the hydrogen flow rate to 1, 2, 3 l / min with the reaction gas, and the results are shown in FIG . 9 . .

When hydrogen was injected into the reaction gas, the decomposition rate was higher than when CF ₄ alone was injected or oxygen was injected into the reactor. If certain CF flow rate (1, 2, 3ℓ / min ) of hydrogen was added under ₄ As this increase to increase the decomposition rate of CF ₄ flow rate of the hydrogen 3ℓ / min day decomposition rate of CF ₄ is the decomposition rate of CF ₄ to about 0.85 This was found to be very high. Therefore, when CF ₄ is decomposed into thermal plasma, it is preferable to inject the reaction into a thermal plasma space such that CF ₄ : hydrogen is 1: 1 to 1: 4 (L / min).

Example 17 CF According to Hydrogen Flow Rate Change ₄ Decomposition of 2

The decomposition rate of CF ₄ was measured in the same manner as in Example 16 except that the plasma power was performed at 9 kW, and the results are shown in FIG. 9 .

Decomposition rate of CF ₄ due to the difference of the plasma power was largely not affected if the incoming hydrogen of 3 ℓ / min with increasing the hydrogen flow rate is increased, the decomposition rate of CF ₄ was able to decompose the CF ₄ to 80 or more.

Example 18 CF According to Power Variation ₄ Decomposition of 1

10 shows the decomposition rate of CF ₄ when the plasma power was changed to 6, 7.5, and 9 kW at a voltage of 30 V, a current of 200 to 300 A, an argon flow rate of 15 L / min, and a CF ₄ flow rate of 1 L / min.

As the plasma power increased, the decomposition rate of CF ₄ tended to increase slightly, but it did not significantly affect the decomposition rate of CF ₄ . This result is considered to be because the temperature of the plasma does not change significantly even if the power increases.

Example 19 CF According to Power Variation ₄ Decomposition of 2

The decomposition rate of CF ₄ was measured in the same manner as in Example 18, except that CF ₄ was flowed at a flow rate of 2 L / min, and the results are shown in FIG. 10 .

Jueodo increase the plasma power if compared to the embodiment that the decomposition rate of CF ₄ is much change were conducted above embodiment gives flown the CF ₄ flow rate of 1ℓ / min in Example 18. The more inflow amount of CF ₄ dripping the decomposition rate of CF ₄ I could see that.

<Example 20> CF when oxygen and hydrogen are added simultaneously ₄ Decomposition of 1

The plasma power 6kW, argon flow rate of 15ℓ / min, CF ₄ flow rate of 1ℓ / min, hydrogen flow rate was fixed to 1ℓ / min and measuring the amount of going by increasing the oxygen flow rate to 0.5, 1, 1.5ℓ decomposing CF ₄ CF ₄ The decomposition rate is shown in FIG. 11 .

When oxygen and hydrogen were added together, it was slightly higher than the decomposition rate when oxygen was added alone, but showed a lower decomposition rate than when only hydrogen was added. This is because when hydrogen and oxygen are added at the same time, hydrogen or oxygen and CF ₄ are bonded in the plasma, but hydrogen and oxygen dissociated in the plasma may be bonded to each other between two atomic species.

Example 21 CF when Oxygen and Hydrogen were Simultaneously Added ₄ Decomposition of 2

Except that the plasma power was performed at 9kW, the decomposition rate of CF ₄ was measured in the same manner as in Example 20, and is shown in FIG. 11 .

The decomposition rate of CF ₄ was not significantly affected by the difference in plasma power, and when oxygen and hydrogen were added simultaneously as the reaction gas, the decomposition rate of CF ₄ was not so high even when the oxygen flow rate was increased.

As described above, the method of the present invention can rapidly convert CFCs and PFCs, which are global warming and ozone depleting substances and hardly decomposable organic substances, in thermal plasma over 10,000 K and then recombine with the reactant to convert them into materials that are easy to process. Compared to the conventional decomposition method, it can be applied industrially as it is advantageous for large-capacity treatment, and it can reduce environmental pollution since it is less likely to be recontaminated and can be converted into a material that can be used as a renewable resource.

Claims (10)

1) generating hydrogen chloride, hydrogen fluoride, carbon monoxide, carbon dioxide, or water by passing a mixed gas of chlorofluorocarbon (CFC) or perfluoride (PFC) and perfluoro compounds (PFC) into a direct thermal plasma space; Step 1), 2) quenching of the product obtained from step 1 (step 2) and 3) A method for decomposing and treating CFCs or PFCs, comprising the step of detoxifying the quenched product obtained from step 2 (step 3). The method for decomposing and treating CFCs or PFCs according to claim 1, wherein the reactor gas is a single or more gas selected from the group consisting of air, nitrogen, oxygen, hydrogen, and water vapor. The method for decomposing and treating CFCs or PFCs according to claim 1, wherein the CFCs are CFC 11 (CFCl ₃ ), CFC 12 (CCl ₂ F ₂ ), or CFC 113 (C ₂ Cl ₃ F ₃ ). The method for decomposing and treating CFCs or PFCs according to claim 1, wherein the PFC is CF ₄ , C ₂ F ₆ , NF _3, or SF ₆ . The method for decomposing and treating CFCs or PFCs according to claim 1, wherein the direct current thermal plasma of step 1 is generated using argon. The method for decomposing and treating CFCs or PFCs according to claim 1, wherein the temperature of the direct-current thermal plasma in step 1 is 1,000 to 10,000 占 폚. The process for decomposing and treating CFCs or PFCs according to claim 1, wherein the detoxification step in step 3 is reacted with a basic substance. 8. The method for decomposing and treating CFCs or PFCs according to claim 7, wherein the basic substance uses an aqueous sodium hydroxide solution and an aqueous calcium oxide solution. The CFC according to claim 1, wherein the flow rate ratio of the mixed gas in step 1 is injected into the thermal plasma space such that CFC113: oxygen: hydrogen = 1: 1: 3 to 1: 3: 3 (mol / s). Or PFC decomposition and treatment method. The decomposition of CFCs or PFCs according to claim 1, wherein the flow rate ratio of the mixed gas in step 1 is injected into a thermal plasma space such that CF ₄ : hydrogen = 1: 1: 1: 4 (l / min). Treatment method.