JP2007225124A - Decomposing method of halogen compound and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for efficiently and completely decomposing a halogen compound while stabilizing flame and reducing the generation of soot. <P>SOLUTION: The halogen compound, a primary gas including oxygen more than that of air, and a combustible substance such as a propane gas are mixed in advance, the obtained mixture is introduced to a burner 11, and a secondary gas is introduced to the neighborhood of the flame of the burner 11 and burned, to decompose the halogen compound. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a halogen compound decomposition method for decomposing and detoxifying halogen compounds such as chlorofluorocarbon, and an apparatus therefor.

Halogen compounds such as chlorofluorocarbons are chemically stable regardless of organic halogen compounds and inorganic halogen compounds, and have been widely used as refrigerants, cleaning agents, foaming agents, aerosol propellants and the like. However, halogen compounds released into the atmosphere are attracting attention as substances that cause global warming and destroy the ozone layer, and technologies for recovering and decomposing halogen compounds such as CFCs have been researched and developed.
However, these halogen compounds are usually non-flammable and stable compounds, and a method for decomposing halogen compounds such as chlorofluorocarbon is required and studied for the protection of the global environment.

As main methods for decomposing halogen compounds such as chlorofluorocarbons, there are a combustion decomposition method, a plasma decomposition method, and a catalytic decomposition method.
The combustion decomposition method is a method in which a halogen compound is blown into a flame little by little and decomposed at a high temperature. In this case, the combustion reaction of halogen compounds such as chlorofluorocarbons is an endothermic reaction, and in order to decompose, a large amount of fuel, which is a large amount of energy source for the combustion reaction, is necessary, the flame is unstable, In some cases, the apparatus is enlarged, and the amount of processing is small and inefficient compared to the ratio of combustible gas (for example, see Patent Document 1). Therefore, a stable combustion decomposition method with good decomposition efficiency has been demanded.

  In the plasma decomposition method, a discharge electrode and an induction electrode are arranged with a dielectric interposed therebetween, and a high-voltage pulse voltage is applied between these electrodes to generate a discharge between the electrodes, and pass therethrough. There are those that decompose halogen compounds (for example, see Patent Document 2) and those that decompose arc plasma. However, when trying to completely disassemble, the input power increases and the processing cost increases. However, no matter how large the input power is, the decomposition rate is slightly insufficient exceeding 90%. The decomposition rate was reduced to 40%.

  In the catalytic decomposition method, a halogen compound to be decomposed is brought into contact with the catalyst layer for decomposition (see, for example, Patent Document 3). In this case, the decomposition time is long and may take 10 hours or more, and the processing efficiency is insufficient. Further, there are problems in maintaining the reaction activity of the catalyst and maintaining the catalyst life. Further, each component of the halogen compound can be decomposed and cannot be decomposed, and there has been a problem in actually performing the decomposition process.

JP-A-8-224441 JP-A-4-322718 JP 2000-15060 A

  Therefore, an object of the present invention is to provide a method and an apparatus for efficiently and completely decomposing a halogen compound, in which a flame is stable and soot generation is small.

  In order to solve the above-mentioned problems, the present invention of claim 1 is characterized in that a halogen compound, a primary gas containing more oxygen than air, and a combustible material are mixed in advance, and the resulting mixture is introduced into the burner, and the secondary gas is introduced into the burner. Is a method for decomposing a halogen compound by decomposing a halogen compound and decomposing the halogen compound.

  In the present invention of claim 1, a halogen compound, a primary gas containing more oxygen than air, and a combustible material are mixed in advance, the resulting mixture is introduced into a burner, a secondary gas is introduced into the burner, and burned. Since the compound has been decomposed, each substance can be reliably mixed at the desired mixing ratio, the halogen compound can be decomposed at a high concentration with respect to the combustible substance, and the flame is stabilized, backfire, flame blow-off and extinction Does not occur, and there are few occurrences of wrinkles. Further, the halogen compound has a high decomposition rate, and can be decomposed with high efficiency.

  As the combustible material, combustible gas and combustible liquid can be used. As the combustible gas, hydrogen and hydrocarbons such as methane, ethane, propane, ethylene, and natural gas can be used. Further, the flammable liquid is preferably a vaporized liquid, and gasoline, alcohol and ethanol, methanol, etc. can be used as the hydrocarbon.

  The present invention of claim 2 is a method for decomposing a halogen compound, wherein the primary gas has an oxygen content of 21% or more.

  In the present invention of claim 2, since the oxygen content of the primary gas is 21% or more, the amount of oxygen is greater than that of air, the combustible material and oxygen can be sufficiently mixed, and the combustible material is burned at a high temperature. And the halogen compound can be efficiently decomposed.

  The present invention of claim 3 is a method for decomposing a halogen compound, wherein the oxygen content of the secondary gas is 20% to 60%.

  In the present invention of claim 3, since the oxygen content of the secondary gas is 20% to 60%, the combustible material can be completely burned at a high temperature together with the oxygen of the primary gas, and soot is generated. Less halogen compounds can be completely decomposed at a high decomposition rate. If it is 20% or less, a sufficient decomposition rate cannot be obtained, and harmful by-products are generated even when the decomposition rate is high. Concentrating the oxygen concentration of the secondary gas to 60% or more is expensive, is not preferable in terms of cost, and is not preferable in terms of safety.

  The present invention of claim 4 is the method for decomposing a halogen compound, wherein the mixing ratio of the halogen compound and the combustible material is such that the ratio of the halogen compound and the combustible material is in the range of 0.2 to 10.0 in terms of molar ratio.

  In the present invention of claim 4, the mixing ratio of the halogen compound and the combustible substance is such that the ratio of the halogen compound and the combustible substance can be decomposed in the range of 0.2 to 10.0 in molar ratio. It is possible to decompose over a wide mixing range of many types of halogen compounds and combustible materials, from low rates to high rates of 10.0. If it is 0.2 or less, a large amount of combustible material is required for the halogen compound, which is not efficient. If it is 10.0 or more, a sufficiently high temperature cannot be obtained and the decomposition rate decreases.

  According to the present invention of claim 5, the mixing ratio of the primary gas and the secondary gas to the combustible substance is such that the ratio of the theoretical gas necessary for complete combustion of the introduced primary gas and secondary gas and the combustible substance is a molar ratio. This is a decomposition method of a halogen compound in the range of 1.0 to 15.0.

  In the present invention of claim 5, the combined amount of primary gas and secondary gas with respect to the combustible material is in the range of 1.0 to 15.0 with respect to the theoretical gas required for complete combustion of the combustible material. Therefore, the combustible substance can be burned completely, soot is not generated, and the halogen compound can be decomposed at a high decomposition rate. If it is 1.0 or less, the combustible material is incompletely burned and soot is generated, and if it is 15.0 or more, the amount of air is increased, the flame temperature is lowered, and the decomposition rate of the halogen compound is lowered.

  The present invention of claim 6 is the method for decomposing a halogen compound, wherein the halogen compound is an organic halogen compound containing fluorine and the combustible substance is a hydrocarbon or an alcohol.

  In the present invention of claim 6, since the combustible substance is a hydrocarbon or an alcohol, it can be burned at a high temperature, easily generates radicals, and has a long radical lifetime, so it is easy to decompose an organic halogen compound containing fluorine. . The generated radicals are easier to decompose the organic halogen compound containing fluorine.

  The present invention of claim 7 is an apparatus for treating a halogen compound by mixing a halogen compound with a combustible substance and burning the resulting mixture with a burner, wherein the combustion part of the burner contains more oxygen than the halogen compound and air. This is a halogen compound processing apparatus that introduces a mixture obtained by previously mixing a primary gas and a combustible material, and further introduces a secondary gas around the combustion portion of the burner to decompose the halogen compound.

According to the seventh aspect of the present invention, a gas mixture obtained by previously mixing a halogen compound, a primary gas containing more oxygen than air, and a combustible substance is introduced into the combustion part of the burner of the halogen compound processing apparatus. It is possible to reliably mix a halogen compound and a primary gas containing more oxygen than air at a desired mixing ratio, and to burn a combustible material and a halogen compound at a high temperature with less soot generation. The compound can be completely decomposed.
Since the secondary gas is introduced around the burning part of the burner and the halogen compound is decomposed, the flame is stable, the combustible substance can be completely burned, and the halogen compound can be reliably decomposed.

  The present invention according to claim 8 is the halogen compound processing apparatus in which the primary gas and the secondary gas containing more oxygen than air are produced using an oxygen-enriched membrane.

  In the present invention of claim 8, since the primary gas and the secondary gas containing more oxygen than air are produced using an oxygen-concentrated membrane, the necessary amount can be produced immediately at a low cost. In addition, the equipment is simple, and a primary gas and a secondary gas containing more oxygen than air can be produced in the vicinity of the halogen compound processing apparatus, and handling is easy.

  The present invention according to claim 9 is the halogen compound processing apparatus in which the oxygen content of the primary gas introduced into the burner of the burner is 21% or more and the oxygen content of the secondary gas is 20% to 60%.

  In the present invention of claim 9, the oxygen content of the primary gas introduced into the combustion part of the burner is 21% or more, and the oxygen content of the secondary gas is 20% to 60%. The halogen compound can be burned and the halogen compound can be efficiently decomposed.

  According to the tenth aspect of the present invention, the mixing ratio of the halogen compound and the combustible substance introduced into the burning part of the burner is such that the ratio of the halogen compound and the combustible substance is in the range of 0.2 to 10.0 in terms of molar ratio. The mixing ratio of the primary gas and the secondary gas is such that the ratio of the theoretical gas necessary for complete combustion of the introduced primary gas and secondary gas and the combustible material is in the range of 1.0 to 15.0 in terms of molar ratio. It is a certain halogen compound processing apparatus.

In the present invention of claim 10, the mixing ratio of the halogen compound and the combustible substance introduced into the burning part of the burner is such that the ratio of the halogen compound and the combustible substance is in the range of 0.2 to 10.0 in terms of molar ratio. Many kinds of halogen compounds can be decomposed in a wide range by adjusting the amount of the substance.
The mixing ratio of the combustible material, the primary gas and the secondary gas is such that the ratio of the theoretical gas necessary for complete combustion of the introduced primary gas and secondary gas and the combustible material is 1.0 to 15.0 in terms of molar ratio. Therefore, the combustible substance can be completely burned at a high temperature, so that generation of soot and by-products can be prevented, and the halogen compound can be completely decomposed.

  The present invention of claim 11 is a halogen compound processing apparatus in which a heating part for heating a mixture of a halogen compound and a combustible substance by electricity is provided in the combustion part of the burner.

  In the present invention of claim 11, since the heating part such as a filament for heating the mixture of the halogen compound and the combustible substance by electricity is provided in the combustion part of the burner, the combustion substance can be completely burned and generated from the filament. The decomposition of the halogen compound by the thermal electrons and the radicals generated by the decomposition promote the decomposition of the halogen compound, and a high decomposition rate can be obtained.

  The present invention of claim 12 is the halogen compound processing apparatus in which the combustion gas decomposed by the burner is wet-cleaned with water by the cleaning apparatus.

In the present invention of claim 12, since the combustion gas decomposed by the burner is wet-washed with water by the cleaning device, halides in the combustion gas can be removed.
The burned gas can be only harmless carbon dioxide (CO ₂ ) or water vapor (H ₂ O). Then, fluorine (F) and chlorine (Cl) can be recovered and reused. In addition, since water or an alkaline aqueous solution is injected into the reaction gas, the temperature of the reaction gas can be rapidly lowered, and the temperature can be reduced to the outside and exhausted.

Thereafter, when the cleaning solution is treated with an alkaline aqueous solution, hydrogen halides such as hydrogen fluoride (HF) and hydrogen chloride (HCl) produced by decomposition of the halogen compound are converted into sodium hydroxide (NaOH) and calcium chloride (CaCl). ₂ ), it can be absorbed by an alkaline aqueous solution such as calcium hydroxide (Ca (OH) ₂ ), neutralized and rendered harmless.
At this time, detoxified hydrogen fluoride (HF) can be precipitated and recovered, for example, as calcium fluoride (CaF ₂ ) having low solubility, and hydrogen chloride (HCl) is recovered as sodium chloride (NaCl). be able to.

  According to the present invention, the halogen compound is prepared by previously mixing a primary gas containing more oxygen than air and a combustible material, introducing the resulting mixture into a burner, and further introducing a secondary gas into the burner. Since it is burned, it is possible to provide a small-sized method and apparatus that can be decomposed with high efficiency and reliability.

Embodiments of the present invention will be described with reference to the drawings.
Hereinafter, with regard to the embodiments of the present invention, a chlorofluorocarbon gas (CFC-12), which is one of organic halogen compounds containing fluorine as a halogen compound, and propane gas as a combustible material, as an example, a decomposition treatment method and apparatus However, the present invention is not limited to this example.
Examples of the organic halogen compound to be decomposed include CFCs such as chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC), and perfluorocarbon (PFC). Examples of the inorganic halogen compound include sulfur hexafluoride (SF ₆ ), nitrogen trifluoride (NF ₃ )), and the like.

FIG. 1 shows a schematic diagram of a processing apparatus for halogen compound containing fluorine.
The halogen compound processing apparatus is roughly divided into a combustion apparatus 10 for burning and decomposing halogen compounds, a flow rate control apparatus 20 for controlling the flow rate of gas sent to the combustion apparatus 10, a cleaning apparatus 30 for cleaning combustion gas decomposed, and a cleaning process. Formed from a precipitation device 40 for precipitating the halide of the cleaning liquid discharged from the device 30, and an oxygen concentrating device 50 for increasing the oxygen content of the air sent to the flow rate control device 20, and each connected by a pipe as shown in FIG. Has been. Each device will be described below.

  First, the combustion apparatus 10 will be described. A cross-sectional view of the combustion apparatus 10 is shown in FIG. In the combustion apparatus 10, a burner 11 is installed in a cylindrical combustion cylinder 13, and a filament 12, which is a heating unit, is attached to a portion where the flame on the upper part of the burner 11 extends. An electric wire 17 is connected to the filament 12 and is connected to an external power source to be heated. When the filament 12 is used, the decomposition rate is improved in proportion to the overheated current, and the flame is stabilized. However, the halogen compound can be decomposed even without the filament 12 or only by burning the flame. In addition, the thing which can heat a flame other than the filament 12 can be used as a heating part.

  The combustion cylinder 13 is made of a long cylinder so that it can withstand the high temperature emitted from the flame of the burner 11 as long as it is resistant to corrosion. For example, ceramic or heat-resistant alloy can be used.

  Connected to the lower portion of the combustion cylinder 13 are a primary gas introduction pipe 14 for blowing primary gas sent from a flow rate control device 20 described later, and a secondary gas introduction pipe 15 for blowing secondary gas from the flow rate control device 20. ing. The primary gas introduction pipe 14 is connected to the bottom of the burner 11 and blows the primary gas into the burner 11. The secondary gas introduction pipe 15 is connected to an air outlet provided at the bottom of the combustion cylinder 13 so that the secondary gas can be blown in the vicinity of the flame on the outer peripheral portion of the burner 11.

A combustion gas discharge pipe 16 that blows combustion gas obtained by combustion decomposition of a halogen compound to the cleaning device 30 is provided at the upper portion of the combustion cylinder 13.
An exhaust gas analyzer 60 is connected to the combustion gas discharge pipe 16 in order to measure the components of the combustion gas. As the exhaust gas analyzer 60, for example, a gas chromatography mass spectrometer (GC-MS) is used.

Next, the flow control device 20 will be described. The flow rate control device 20 includes a control panel 27 that controls the flow rate of gas, a CFC gas cylinder 21 that sends gas to the control panel 27, an LPG cylinder 22, and an air cylinder 23.
The chlorofluorocarbon cylinder 21 is filled with chlorofluorocarbon gas (CFC-12), which is a recovered organic halogen compound, and is connected to a control panel 27 by a chlorofluorocarbon introduction pipe 24.

The LPG cylinder 22 is filled with propane gas and is connected to the control panel 27 by an LPG introduction pipe 25.
The air cylinder 23 is filled with air and is connected to the control panel 27 by an air introduction pipe 26. The air introduction pipe 26 is branched into two on the way, and is divided into a primary gas and a secondary gas, which will be described later, and is connected to the control panel 27.

The air filled in the air cylinder 23 can be filled with air having a normal oxygen concentration or air having the oxygen concentration concentrated by the oxygen concentrator 50 as described later. When air having different oxygen concentrations is sent to the control panel 27, two types of air cylinders 23 having different oxygen concentrations can be provided.
In addition, when it is desired to create air in which the oxygen concentration is concentrated without using the oxygen concentrator 50, both the oxygen cylinder and the air cylinder 23 are installed, and the desired oxygen cylinder is separated from the oxygen in the air. Of oxygen is fed into the flow control device 20.

Instead of the air cylinder 23, the oxygen concentration device 50 can blow the air with the oxygen concentration concentrated directly to the flow rate control device 20.
An outline of the oxygen concentrator 50 is shown in FIG. The oxygen concentrator 50 first includes a compressor 51 that compresses air, a mist cache 52 that removes dust in the compressed air, and an air dryer 53 that dries the air from which dust has been removed. Furthermore, it has the 1st oxygen concentration film | membrane cylinder 54 and the 2nd oxygen concentration film | membrane cylinder 55 which packed the film | membrane which concentrates oxygen.

  The dried compressed air that has come out of the air dryer 53 passes through the air introduction pipe 56 and enters the first oxygen-concentrated membrane cylinder 54, and the oxygen-enriched air passes through the primary concentrated air pipe 57 and enters the second oxygen-concentrated membrane cylinder 55. The oxygen concentration is further concentrated. In the first oxygen enriched membrane cylinder 54, the oxygen concentration is concentrated to about 40%, and in the second oxygen enriched membrane cylinder 55, the oxygen concentration is further enriched to about 60%.

The air enriched in oxygen concentration passes through the secondary concentrated air pipe 58 and is filled into the air cylinder 23 or directly blown to the flow rate control device 20. The oxygen concentration can be increased by increasing the number of oxygen concentrating membranes or by increasing the number of oxygen concentrating tubes.
The air whose nitrogen concentration has increased after the oxygen has been concentrated is discharged from the first oxygen-concentrated membrane cylinder 54 and the second oxygen-concentrated membrane cylinder 55 through the nitrogen exhaust pipe 59, respectively.

Next, the cleaning device 30 will be described. The combustion gas of chlorofluorocarbon gas (CFC-12), which is an organic halogen compound burned and decomposed in the combustion device 10, is sent to the cleaning device 30.
The cleaning device 30 has a cylindrical cleaning cylinder 31 that is installed upright in the vertical direction. A cleaning liquid pipe 35 is connected to the ceiling of the cleaning cylinder 31 so that the cleaning liquid flows down like a shower. A combustion gas inlet 32 is provided in the upper part of the cleaning cylinder 31 slightly lower than the ceiling of the cleaning cylinder 31, and combustion and decomposed combustion gas are introduced.

A cleaning liquid tank 33 is provided at the bottom of the cleaning cylinder 31 and stores a cleaning liquid for cleaning the combustion gas. The cleaning liquid in the cleaning liquid tank 33 passes through the cleaning liquid pipe 35 by the cleaning liquid pump 34 and is circulated to the ceiling of the cleaning cylinder 31 as described above. A part of the cleaning liquid is sent to the precipitation device 40 described later by switching the valve.
The combustion gas cleaned with the cleaning liquid is discharged from a cleaning gas discharge pipe 36 provided at the upper part of the cleaning liquid tank 33.

The precipitation device 40 has a precipitation tank 41, and a washing liquid introduction pipe 42 branched from the washing liquid pipe 35 is connected to the upper part of the precipitation tank 41. The cleaning liquid introduced into the precipitation tank 41 is charged with calcium hydroxide (Ca (OH) ₂ ) or the like, as will be described later, to precipitate and remove halides such as fluorine. The cleaning liquid from which the halide such as fluorine has been removed is returned to the cleaning liquid tank 33 and can be used.

Next, a method for decomposing and recovering chlorofluorocarbon gas (CFC-12), which is an organic halogen compound, will be described.
As shown in FIG. 1, the CFC-12 to be decomposed is stored in a CFC gas cylinder 21 and connected so as to flow from the CFC gas cylinder 21 into the flow rate control device 20 of the combustion apparatus 10. Similarly, LPG which is a combustion gas and air containing a large amount of oxygen are connected so as to flow into the flow control device 20.
The CFC-12 is controlled to a predetermined flow rate by the control panel 27 of the flow rate control device 20, sent to the primary gas introduction pipe 14, and as the primary gas in the primary gas introduction pipe 14 before being sent to the burner 11. Mix evenly.

The mixed primary gas is sent to the lower part of the burner 11. Since the filament 12 which is a heating part is provided in the combustion part where the primary gas of the burner 11 burns, the primary gas burns because electricity is energized to the filament 12 and heated to a high temperature. At this time, since the secondary gas flows into the vicinity of the burner 11, the propane gas in the primary gas is completely burned, and the CFC-12 is completely decomposed.
As the air mixed with the primary gas and the air used as the secondary gas, one having an increased oxygen content can be used. The relationship between the oxygen content and the decomposition of CFC-12 will be described later.

  The decomposition combustion of CFC-12 will be described. The air ratio is the amount of air that actually flows into the combustion apparatus 10 (the amount of oxygen increased) with respect to the amount of air required to completely burn LPG, which is a combustible material (the same applies to the amount of air that increased oxygen). The amount of air is also the same), and 1.0 or more means that the air for burning LPG is in excess of the theoretical amount. Moreover, CFC / LPG ratio means the molar ratio of CFC-12 and LPG (the whole quantity is regarded as propane gas). The decomposition rate of CFC-12 indicates the ratio of decomposition in CFC-12 introduced into the combustion apparatus 10.

CFC-12 introduced into the combustion apparatus 10 undergoes the following combustion reaction depending on the CFC / LPG ratio due to LPG and oxygen in the air.
CF ₂ Cl ₂ + C ₃ H ₈ + 5O ₂ → 4CO ₂ + 2HCl + 2HF + 2H ₂ O (1)
2CF ₂ Cl ₂ + C ₃ H ₈ + 5O ₂ → 5CO ₂ + 4HCl + 4HF (2)
_{3CF 2 Cl 2 + C 3 H} 8 + 6O 2 → 6CO 2 + 4HCl + 4HF + F 2 + Cl 2 (3)

When the CFC / LPG ratio is changed from 1 to 2 and the amount of CFC-12 is increased, as described in the above formulas (1) and (2), water (H ₂ O) is used under the condition that sufficient oxygen is present. ) Is reduced, and hydrogen chloride (HCl) and hydrogen fluoride (HF) are increased. Furthermore, as the CFC / LPG ratio increases from 2 to 3, the required amount of oxygen increases as described in Equations 2 and 3 above, but in addition to hydrogen chloride (HCl) and hydrogen fluoride (HF) Fluorine (F ₂ ) and chlorine (Cl ₂ ) are generated. As described above, when the CFC / LPG ratio is 2 or more, if there is not enough oxygen, unburned products and by-products may be generated. Further, the decomposition rate is improved by adding water vapor.

  CFC-12, LPG, and air are mixed in advance to create a primary gas, which is sent to the burner 11 and CFC-12 is decomposed by premixed diffusion combustion in which a secondary gas containing oxygen is blown from the periphery of the burner 11. The results are shown in FIG. In FIG. 4, when the air ratio is 0.8, 1.0, and 1.2, the CFC / LPG ratio was changed and the decomposition rate of CFC-12 was measured.

When the air ratio was 1.0 and 1.2, the CFC / LPG ratio almost completely decomposed to near 1.6, and when it exceeded 1.6, the decomposition rate decreased rapidly. When the air ratio was 0.8, the CFC / LPG ratio was almost completely decomposed to near 0.7, but when it exceeded 0.7, the decomposition rate decreased rapidly.
Moreover, when the air ratio was 1.0 or more, no generation of soot was observed. Furthermore, when the air ratio is 1.0 or more, the combustion gas was analyzed using GC-MS. As a result, the unburned content of CFC-12 and LPG was extremely reduced, and C ₂ H ₂ F ₂ And generation of by-products such as C ₂ H ₃ F were hardly observed.

Furthermore, when C ₂ F ₆ was decomposed, it was confirmed that when the air ratio was 1.0 or more, the C ₂ F ₆ / LPG ratio was almost completely decomposed until 8.6. Further, when decomposing HCFC-22, if the air ratio is 1.0 or more, the HCFC-22 / LPG ratio can be almost completely decomposed up to 10.0.

As described above, the mixing ratio of the organic halogen compound to be decomposed and the combustion substance LPG can be decomposed in a wide range of 0.2 to 10.0 in the premixed diffusion combustion.
In this premixed diffusion combustion, even if the amount of CFC-12 increases more than twice, there is no detection of decomposition by-products.
In addition, in the amount of air with respect to the combustible substance, the ratio of the sum of the amount of air for completely combusting the combustible substance and the amount of air of the primary gas and the secondary gas introduced into the burner 11 is insufficient when oxygen is 1.0 or less. As a result, the combustible material burns incompletely, soot is generated, and if it is 15.0 or more, the amount of air blown into the flame increases, the flame temperature decreases, and the decomposition rate of the organic halogen compound decreases.

  For comparison, the secondary gas for burning LPG is not blown from the periphery of the burner 11, but CFC-12, LPG, and all air for burning LPG are mixed in advance to create a primary gas to burner 11. FIG. 5 shows the case of the premixed combustion sent to. In the case of premixed combustion, when the air ratio is 0.8, 1.0 and 1.2, the CFC / LPG ratio is almost completely decomposed to near 1.7, and rapidly exceeds 1.7. Degradation rate decreased. In the case of premixed combustion, soot is generated when the air ratio is 1.0 or more, and a change in the flow rate of the supply gas (primary gas) may cause a flame to blow out or backfire. The nature is low.

  For comparison, diffusion is performed by mixing CFC-12 and LPG in advance without mixing air, creating a primary gas, sending it to the burner 11, and blowing a secondary gas containing oxygen from around the burner 11. The case of combustion is shown in FIG. In the case of diffusion combustion, when the air ratio was 0.63, the CFC / LPG ratio increased in the vicinity of 0.8, but with other air ratios, only a decomposition rate of about 50 to 70% was obtained. When the air ratio is 1.0 and 1.25, the CFC / LPG ratio is almost completely decomposed to near 0.8, and when it exceeds 0.8, the decomposition rate decreases rapidly. No wrinkles were observed.

Next, FIG. 7 shows the relationship between the oxygen concentration of the primary gas and the secondary gas and the decomposition rate. 7, which in the degradation of CF _4, is five changing the oxygen concentration of the primary gas to 0% to 60%, was measured decomposition rate of CF ₄ by changing the oxygen concentration of secondary air at each concentration It is.
When the oxygen concentration of the primary gas is 0%, the decomposition is performed only when the oxygen concentration of the secondary gas is 100%, and the decomposition rate is only about 60%.
When the oxygen concentration of the primary gas is 21%, a decomposition rate of about 80% can be achieved when the oxygen concentration of the secondary gas exceeds 60%. The oxygen concentration of the primary gas of 21% is the oxygen concentration in the air in the natural state. Therefore, when the oxygen concentration of the primary gas is 21% or more, decomposition of the halogen compound can be made effective.

  However, when the oxygen concentration of the primary gas is 36%, a decomposition rate of about 80% can be achieved even if the secondary gas has the same oxygen concentration as natural air. Even when the oxygen concentration of the secondary gas is 60% or more, the decomposition rate hardly changes. When the oxygen concentration of the secondary gas is set to 60% or more, the cost of oxygen concentration increases, which is not preferable. Further, if the oxygen concentration of the secondary gas is set to 60% or more, the risk of the entire system increases when mixed with a combustible substance, which is not preferable.

Next, the combustion gas of the halogen compound (CFC-12) decomposed by the combustion of the combustible material is sent to the cleaning device 30 and cleaned with water in the cleaning cylinder 31. The cleaning water removes hydrogen chloride (HCl) and hydrogen fluoride (HF) in the combustion gas, and the cleaning water is stored in the cleaning liquid tank 33. As for this cleaning liquid, those having low concentrations of hydrogen chloride (HCl) and hydrogen fluoride (HF) are circulated in the cleaning device 30 and sent to the precipitation device 40 when the concentration increases.
The temperature of the combustion gas is lowered by the cleaning liquid and can be discharged from the cleaning gas discharge pipe 36.
The washing water may be an alkaline aqueous solution containing sodium hydroxide (NaOH). In this case, hydrogen chloride (HCl) is recovered as sodium chloride (NaCl).

In the precipitation device 40, slaked lime (Ca (OH) ₂ ) is introduced into the cleaning water, and hydrogen chloride (HCl) and hydrogen fluoride (HF) in the cleaning liquid are precipitated and removed as fluorite (CaF ₂ ). At the same time, it is removed as calcium chloride (CaCl ₂ ). It is desirable that the cleaning water from which hydrogen chloride (HCl) and hydrogen fluoride (HF) have been removed be returned to the cleaning device 30 for circulation.

It is the schematic of the processing apparatus which is the embodiment of this invention. It is the schematic of the combustion part of the combustion apparatus which is the embodiment of this invention. It is a conceptual diagram of the oxygen concentrator which is an embodiment of the present invention. It is a graph which shows the result of having processed fluorofluorocarbon by the premixing diffusion decomposition method of this invention. It is a graph which shows the result of having processed fluorofluorocarbon by the decomposition method of premix combustion. It is a graph which shows the result of having processed fluorofluorocarbon by the decomposition | disassembly method of diffusion combustion. It is a graph which shows the result of having processed the perfluorocarbon and the hydrochlorofluorocarbon by changing the oxygen concentration of a primary gas and a secondary gas by the premixing diffusion decomposition method of this invention.

Explanation of symbols

10 Combustion device 11 Burner 12 Heating part (filament)
20 Flow control device 30 Cleaning device 40 Precipitation device 50 Oxygen concentrator
60 Exhaust gas analyzer

Claims (12)

  A mixture of a halogen compound and a primary gas containing more oxygen than air and a combustible material in advance, introducing the resulting mixture into a burner, introducing a secondary gas into the burner and burning it, and decomposing the halogen compound. A method for decomposing a halogen compound.   The method for decomposing a halogen compound according to claim 1, wherein the primary gas has an oxygen content of 21% or more.   The method for decomposing a halogen compound according to claim 1 or 2, wherein the secondary gas has an oxygen content of 20% to 60%.   The mixing ratio of the halogen compound and the flammable substance is such that the ratio of the halogen compound and the flammable substance is in a range of 0.2 to 10.0 in terms of molar ratio. Disassembly method.   The mixing ratio of the primary gas and the secondary gas with respect to the combustible substance is such that the ratio of the theoretical gas necessary to completely burn the introduced primary gas and secondary gas and the combustible substance is 1.0 to 15 in terms of molar ratio. The method for decomposing a halogen compound according to any one of claims 1 to 4, which is in a range of 0.0.   6. The method for decomposing a halogen compound according to claim 1, wherein the halogen compound is an organic halogen compound containing fluorine, and the combustible substance is a hydrocarbon or an alcohol. In an apparatus for treating a halogen compound by mixing a halogen compound with a combustible substance and burning the resulting mixture with a burner,
In the burner combustion section, a mixture obtained by previously mixing a halogen compound, a primary gas containing more oxygen than air, and a combustible material is introduced, and a secondary gas is further introduced around the burner combustion section. And a halogen compound processing apparatus for decomposing a halogen compound.   The halogen compound processing apparatus according to claim 7, wherein the primary gas and the secondary gas containing more oxygen than air are produced using an oxygen-concentrated membrane.   The halogen compound processing apparatus according to claim 7 or 8, wherein the oxygen content of the primary gas introduced into the burner of the burner is 21% or more, and the oxygen content of the secondary gas is 20% to 60%. .   The mixing ratio of the halogen compound and the combustible substance introduced into the burning part of the burner is such that the ratio of the halogen compound and the combustible substance is in a range of 0.2 to 10.0 in terms of molar ratio, and the combustible substance and the primary material are mixed. The mixing ratio of the gas and the secondary gas is such that the ratio of the theoretical gas necessary for completely burning the introduced primary gas and secondary gas and the combustible material is in the range of 1.0 to 15.0 in terms of molar ratio. Item 10. The halogen compound processing apparatus according to any one of Items 7 to 9.   The halogen compound processing apparatus according to any one of claims 7 to 10, wherein a heating unit for heating the mixture of the halogen compound and the combustible substance by electricity is provided in the combustion unit of the burner.   The halogen compound processing apparatus according to any one of claims 7 to 11, wherein the combustion gas decomposed by the burner is wet-cleaned with water by a cleaning apparatus.