JP3153733B2 - Combustion decomposition equipment for chlorofluorocarbon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for decomposing chlorofluorocarbon, which is a hazardous waste, by decomposing it by burning and decomposing it using hydrogen or hydrocarbon fuel.

[0002]

2. Description of the Related Art CFCs are extremely stable compounds.
It has been widely used as a spray agent, a foaming agent, a refrigerant, etc. in various places because of its easy handling and liquefaction.However, in recent years, destruction of the ozone layer by Freon gas has become a problem, Attention has been paid to the detoxification process.

However, chlorofluorocarbon is a substance that is very difficult to decompose. Although it does not decompose in a normal combustion treatment in which oxygen is simply supplied to chlorofluorocarbon, the value of the thermodynamic constant relating to the decomposition reaction of fluorocarbon (Table 1) As can be seen from the above, it is known that hydrocarbons such as hydrogen and methane are easily decomposed when they are mixed into the chlorofluorocarbon.

[0004]

[Table 1]

As a method for decomposing CFCs using this principle, a method disclosed in Japanese Patent Application Laid-Open No. 3-51611 is known. In this method, hydrogen or a hydrocarbon-based fuel, which is an auxiliary agent, is mixed into the chlorofluorocarbon gas, and oxygen is supplied to these to burn and decompose the chlorofluorocarbon gas. It is described that by doing so, CFCs perform a thermodynamically favorable reaction, and CFCs that could not be decomposed by a simple combustion treatment only by supplying oxygen are burned and decomposed.

[0006]

By the way, even if methane gas, which is the above-mentioned auxiliary agent, is mixed into chlorofluorocarbon, chlorofluorocarbon cannot be reliably decomposed simply by introducing this mixed gas into the combustion chamber. It has been known. This is evident from the results of tests using a cylindrical burner. That is, when the volume ratio of Freon-12, which is a type of Freon, to methane is 0.2 or less, Freon-12 can be completely decomposed. Degradation rate decreases,
When the capacity ratio becomes about 0.5, the decomposition rate decreases to about 90%. Further, when the capacity ratio is 0.6 or more, a large amount of soot is generated, which causes a problem of incomplete combustion.

Although the above description has been made taking Freon-12 as an example, other types of Freon generally have the same tendency as described above, although the threshold value of the capacity ratio is large or small. Therefore, even if a combustion aid is conventionally mixed with chlorofluorocarbon, the volume ratio must be 0.2 or less, the amount of the combustion auxiliary is about four times as much as that of chlorofluorocarbon, and the processing cost is reduced. There is a problem that it is bulky.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it has been made possible to increase the freon / methane volume ratio, thereby reducing the freon processing cost. It is intended to provide a disassembly device.

[0009]

According to a first aspect of the present invention, there is provided an apparatus for decomposing a chlorofluorocarbon, comprising: a chlorofluorocarbon-containing gas comprising a hydrogen or gaseous straight-chain hydrocarbon as a combustion aid and an oxygen-containing gas; A combustion decomposer for chlorofluorocarbon which mixes and burns to decompose a chlorofluorocarbon-containing gas, comprising: a cylindrical combustion vessel; The burner is disposed so that its center line extends in the tangential direction of the inner peripheral wall surface of the cylindrical combustion vessel, and an exhaust gas treatment device is provided downstream of the combustion vessel to treat exhaust gas generated by the combustion decomposition of chlorofluorocarbon. And the exhaust gas treatment device
An absorption water tank that can retain a neutralizing solution that absorbs and neutralizes
Dissolved salt containing fluorine obtained by neutralization in absorption water tank
And a precipitation tank to precipitate the above-mentioned precipitated salt
And the absorption water tank receives the exhaust gas from the top.
A downcomer tube with an open bottom
Surrounds the Kamer tube and has an open bottom,
An air lift pipe with an overflow section at the top
It is characterized by having .

According to a second aspect of the present invention, there is provided an apparatus for decomposing and decomposing freon according to the first aspect of the present invention, wherein a liquid discharged from the absorbent water tank is provided between the absorption water tank and the reaction tank. A neutralization tank for neutralizing is provided.

According to a third aspect of the present invention, there is provided an apparatus for decomposing and decomposing freon according to the first or second aspect , wherein a pipe for circulating the supernatant of the sedimentation tank to the absorption water tank is provided. It is characterized by being carried out.

According to a fourth aspect of the present invention, there is provided an apparatus for decomposing CFCs according to any one of the first to third aspects, wherein:
A gas washing tower is provided, to which exhaust gas existing in a gas phase space between the absorption water tank and the inner peripheral surface is supplied.

According to a fifth aspect of the present invention, there is provided an apparatus for decomposing CFCs according to any one of the first to third aspects, wherein:
An activated carbon adsorption tank is provided to which exhaust gas present in a gas phase space between the absorption water tank and the inner peripheral surface is supplied.

[0014]

According to the first aspect of the present invention, the chlorofluorocarbon is supplied into the cylindrical combustion vessel at the same time as the auxiliary agent and the oxygen-containing gas in the tangential direction of the inner peripheral wall surface. A swirling flow is formed in the combustion vessel. Due to the formation of this swirling flow, CFCs are reliably and uniformly mixed with the combustion aid and the oxygen-containing gas, and the uniform mixing eliminates the concentration of oxygen present around the CFCs and the combustion aid, thereby reducing the CFCs and auxiliary gases. Uniform combustion of the fuel is promoted, and the combustion temperature rises to a temperature equal to or higher than the decomposition temperature of chlorofluorocarbon, so that chlorofluorocarbon is reliably decomposed. This enables efficient decomposition of CFCs.

[0015] Then, provided burner for cylindrical combustion chamber, since the center line is disposed so as to extend in the tangential direction of the inner peripheral wall surface of the cylindrical combustion chamber is fed from the burner into the combustion vessel The flon, the auxiliary agent, and the oxygen-containing gas are guided by the inner peripheral wall surface and swirl in the container to form a swirling flow. Due to the formation of this swirling flow, CFCs are reliably and uniformly mixed with the combustion aid and the oxygen-containing gas, thereby promoting the combustion of the CFCs and the combustion aids, and raising the combustion temperature to a temperature equal to or higher than the decomposition temperature of the CFCs. By doing so, CFCs are surely decomposed by combustion. This enables efficient decomposition of CFCs.

Further, since the exhaust gas treatment apparatus for treating exhaust gas generated by combustion decomposition of chlorofluorocarbons on the downstream side of the combustion chamber is provided, the exhaust gas discharged from the combustion cracker is processed by the exhaust gas treatment apparatus Is rendered harmless.

[0017] Then, the exhaust gas discharged from the combustion cracker is fed to the downcomer pipe, depress the liquid level in the downcomer pipe by the pressure of the exhaust gas is discharged from the bottom opening in the bubble state, the outer peripheral surface of the downcomer pipe And rises through a gas-liquid contact area between the air-lift tube and the inner peripheral surface of the air-lift tube.
Since the exhaust gas comes into contact with the neutralizing solution in a bubble state,
The contact area of the exhaust gas with the neutralizing solution increases, and the neutralization treatment of the exhaust gas is performed reliably and efficiently.

Further, since the density of the liquid in the gas-liquid contact area decreases due to the generation of the air bubbles, the neutralizing solution in the absorption water tank enters the gas-liquid contact area from the bottom opening of the air lift pipe, and the gas in the same area falls. The liquid in a liquid mixed state is pushed upward and returned from the upper overflow section into the absorption water tank, whereby the neutralized liquid circulates and moves. Therefore, a new neutralizing solution in the absorption water tank is always supplied into the gas-liquid contact area, and the neutralization of the exhaust gas is ensured.

According to the second aspect of the present invention, a neutralization tank is provided between the absorption water tank and the sedimentation tank to neutralize the liquid discharged from the absorption water tank. Unneutralized hydrogen fluoride remaining in the water tank is neutralized in the neutralization tank.

According to the apparatus for decomposing and decomposing freon according to the third aspect of the present invention, since the pipe for supplying the supernatant of the sedimentation tank to the absorption water tank is provided, the pH-adjusted supernatant is supplied through the pipe. It is returned to the absorption tank as a neutralizing solution.

According to the fourth aspect of the present invention, there is provided a gas cleaning apparatus for supplying exhaust gas present in a gas phase space between an outer peripheral surface of an air lift pipe and an inner peripheral surface of the absorption water tank. Since the tower is provided, harmful substances such as hydrogen fluoride and dioxins in the exhaust gas that have accumulated in the space are absorbed and removed by the treatment in the gas cleaning tower.

According to the fifth aspect of the present invention, there is provided an apparatus for adsorbing activated carbon to which exhaust gas present in a gas phase space between an outer peripheral surface of an air lift pipe and an inner peripheral surface of the absorption water tank is supplied. Since the tank is provided, the harmful substances such as hydrogen fluoride and dioxins in the exhaust gas that have accumulated in the space are removed by the treatment in the activated carbon adsorption tank.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing the structure of a device around a combustion vessel of a first embodiment of a flon gas combustion decomposition apparatus according to the present invention. FIG. 3 is a view taken along the line AA of FIG. As shown in these figures, a combustion decomposition apparatus 1 includes a combustion vessel 2 having a hollow interior, and a first burner 21 for supplying a raw material gas G into the combustion vessel 2.
And a second burner 22 for supplying the oxygen-containing gas O into the combustion vessel 2, and a gas mixer 3 for mixing the CFC gas G 1 and the auxiliary agent G 2 into a raw material gas G.

The combustion vessel 2 has a cylindrical shape, and has a combustion chamber 23 lined with a refractory inside. An exhaust gas discharge hole 24 is provided at the bottom of the combustion chamber 23.
The first burner 21 and the second burner 22 are attached to the upper portion of the combustion vessel 2 at a position where the raw material gas G and the oxygen-containing gas O are injected and supplied in a tangential direction of the peripheral wall surface 25 of the combustion chamber 23. ing. In the present embodiment, the injection holes of the first burner 21 and the second burner 22 are provided at positions facing each other on the peripheral wall surface 25,
There is no limitation on their positional relationship, and they may be provided at any position as long as the raw material gas G and the oxygen-containing gas O can be supplied in the tangential direction of the peripheral wall surface 25.

Unillustrated blowers are provided in the passages of the raw material gas G and the oxygen-containing gas O, respectively. By driving these blowers, the raw material gas G and the oxygen-containing gas O are supplied to the first burner 21 and the second burner 21. The fuel is supplied into the combustion chamber 23 through the burner 22. Also,
The combustion chamber 23 is provided with an unillustrated spark discharge terminal or an ignition means composed of a nichrome wire, and the power supply to the ignition means causes the raw material gas G to be ignited.

The gas mixer 3 is formed by a closed container having a hollow inside. The gas mixer 3 is supplied with a chlorofluorocarbon gas G1 and a combustion aid G2, and these are mixed while they are stagnant to form a raw material gas. G and is led out from the bottom toward the combustion vessel 2.

The chlorofluorocarbon gas G1 is chlorofluorocarbon-1
1, Freon-12, Freon-13, Freon-13B1,
Freon-14, Freon-21, Freon-22, Freon-
23, CFC-112, CFC-113, CFC-11
4, Freon-114B2, Freon 115, Freon-11
6, CFC-142b and CFC-152a. In the present invention, those in which other types of gases are mixed into these fluorocarbons are also subject to the treatment as fluorocarbon gas.

As the above-mentioned auxiliary agent G2, methane is preferably used, but in addition to methane, a normal-temperature gaseous linear hydrocarbon such as ethane, propane or butane may also be used. In addition, hydrogen may be used as the auxiliary agent G2 .

According to the above Symbol configuration, the freon gas G1 and combustion improver G2 which is introduced into the gas mixer 3, the gas mixer 3
Are mixed in the inside of the first burner 21 and become the raw material gas G.
And the oxygen-containing gas O is supplied into the combustion chamber 23 through the second burner 22.

The raw material gas G and the oxygen-containing gas O injected from the first burner 21 and the second burner 22
Is that the direction in which the center line of the burner extends extends in the tangential direction of the peripheral wall surface 25, so that the peripheral wall surface 2 of the combustion chamber 23
5, and swirls in the combustion chamber 23. The formation of the swirling flow by this swirling ensures the mixing of the raw material gas G and the oxygen-containing gas O in the combustion chamber 23, whereby the oxygen in the oxygen-containing gas O is uniformly supplied to the auxiliary agent G2. As a result, the combustion and decomposition of the chlorofluorocarbon gas G1 are reliably performed. Exhaust gas W generated by burning and decomposing the chlorofluorocarbon is led out of the combustion chamber 23 through an exhaust gas discharge hole 24.

In this embodiment, the flow rate of the raw material gas G injected from the first burner 21 is set to 30 m / sec, and the flow rate of the oxygen-containing gas O injected from the second burner 22 is set to 70 m / sec. Is set to Further, in the present embodiment, Freon-12 is supplied as the Freon gas G1, methane gas is supplied as the auxiliary agent G2, and air is supplied as the oxygen-containing gas O. The reaction formula in this case is: CCl2F2 + CH4 + 2O2 → 2CO2 + HCl + 2HF. The temperature in the combustion chamber 23 due to this combustion decomposition is 11
00 ° C.

In the present invention, the combustion load factor in the combustion chamber 23 (unit volume (m3) in the combustion chamber 23, calorific value (kcal) of the raw material gas G per unit time (hr))
Is controlled to be 5 × 10 ⁶ to 18 × 10 ⁶ kcal / m ³ · hr. The reason for such control is that if the combustion load factor is less than 5 × 10 ⁶ kcal / m ³ · hr, the temperature in the combustion chamber 23 becomes lower than a predetermined temperature, and the CFC decomposition rate decreases. If the combustion load factor exceeds 18 × 10 ⁶ kcal / m ³ · hr, the residence time of the fluorocarbon gas G1 in the combustion chamber 23 becomes short, and the fluorocarbon decomposition rate decreases.

FIG. 2 is a graph showing the relationship between the combustion load factor and the CFC decomposition rate. This graph shows Freon gas G1
The measured value of the CFC decomposition rate when the CFC / methane volume ratio was set to 0.5 and the air ratio was controlled to 1.2 was used as the combustion load factor. It is plotted in relation to. The temperature in the combustion chamber 23 became 1100 ° C. by the combustion of the raw material gas G under the above conditions. According to this graph, when the combustion load ratio exceeds 18 × 10 ⁶ kcal / m ³ · hr, the CFC decomposition rate, which was almost close to 100%, was 99.99%.
It can be seen that it has decreased to the following.

FIG. 3 is a graph showing the relationship between the ratio of chlorofluorocarbon / methane and the decomposition ratio of chlorofluorocarbon. This graph shows the condition of the combustion load ratio (5 × 10 ⁶ to 18 × 10 ⁶ kcal / m ^3).
After satisfying hr) and controlling the air ratio to 1.2, the chlorofluorocarbon gas G1 was varied by varying the chlorofluorocarbon / methane ratio.
Is a plot of the result of calculating the CFC decomposition rate by subjecting the obtained exhaust gas W to combustion decomposition analysis and analyzing the obtained exhaust gas W. In addition, the dotted line in the graph is a comparative example, and is a case where combustion is performed by a simple cylindrical burner.

As can be seen from the graph of FIG. 3, in the comparative example, when the ratio of chlorofluorocarbon / methane exceeds 0.5, the decomposition ratio of chlorofluorocarbon sharply decreases. While the decomposition rate has dropped to 99.4%, in the present invention, the freon / methane ratio is 0.5%.
When the ratio exceeds 0.9, the change rate at which the CFC decomposition rate decreases is smaller than that in the comparative example, and even when the above ratio is set to 0.9, the CFC decomposition rate remains at 99.6%. Thereby, the combustion chamber 2
Forming a swirling flow within 3 and a combustion load factor of 5
It can be seen that setting within the range of × 10 ⁶ to 18 × 10 ⁶ kcal / m ³ · hr is effective in burning and decomposing CFCs.

FIG. 4 is an explanatory view showing the structure of a device around a combustion vessel of a second embodiment of the chlorofluorocarbon gas combustion decomposition apparatus according to the present invention, wherein (a) is an explanatory view in a side sectional view, and (b) is an explanatory view. It is a BB line view of (a). In the case of this example, an oxygen-containing gas mixer 4 is provided downstream of the gas mixer 3, and the raw material gas G and the oxygen-containing gas O from the gas mixer 3 are supplied to the oxygen-containing gas mixer 4. It has become so. Then, in the oxygen-containing gas mixer 4, the oxygen-containing gas O is mixed and mixed with the raw material gas G in advance. Then, the oxygen-mixed source gas G ′ formed by mixing the source gas G and the oxygen-containing gas O is the first gas.
The fuel is supplied into the combustion chamber 23 through the burner 21. Therefore, in the case of the second embodiment, there is no need to particularly provide the second burner 22.

According to the configuration of the second embodiment, the combustion chamber 2
Since the oxygen-containing gas O is already uniformly dispersed in the oxygen-mixed raw material gas G 'supplied into the combustion chamber 3, the swirl flow and the combustion chamber 2
Combustion decomposition within 3 is ensured.

FIG. 5 shows the combustion decomposition apparatus shown in FIG.
1 and a state in which an exhaust gas treatment device is provided on the downstream side of the combustion decomposition device 1 according to the present invention.
Is an explanatory diagram showing an overall structure of the baked decomposition device. As shown in FIG. This exhaust gas treatment apparatus 50 includes an absorbing water tank 5 provided on the bottom of the combustion chamber 2, reservoir (neutralizing layer) for storing a waste liquid withdrawn from this absorption water tank within 5 6 A reaction tank 7 provided downstream of the storage tank 6 and converting sodium fluoride in the waste liquid into calcium fluoride; a precipitation tank 10 for separating a precipitate generated in the reaction tank 7; p
And an alkaline tank 8 for storing an alkali solution for H adjustment.

The absorption water tank 5 has a ceiling wall 51 at an upper portion for closing the inside of the tank, and the inside of the tank is isolated from the outside by the ceiling wall 51. A communication hole 52 corresponding to the exhaust gas discharge hole 24 is formed in the center of the ceiling wall 51, and the exhaust gas W from the exhaust gas discharge hole 24 is supplied into the absorption water tank 5 through the communication hole 52. ing. And the ceiling wall 5
A downcomer pipe 53 for guiding the exhaust gas W from the communication hole 52 is hung from the lower surface of the communication hole 1, and an air lift pipe 54 surrounds the downcomer pipe 53.
Is drooping.

The bottom of the downcomer pipe 53 is opened toward the absorption water tank 5, and a predetermined number of air holes 53a are formed in the lower peripheral wall. In addition, the bottom of the air lift pipe 54 is positioned lower than the bottom of the downcomer pipe 53 and is opened toward the absorption water tank 5. A liquid drain hole (overflow portion) 54 a is provided above the air lift pipe 54 above the liquid level in the absorption water tank 5. An annular gas-liquid contact area 534 is formed between the outer peripheral surface of the downcomer tube 53 and the inner peripheral surface of the air lift tube 54. In addition, air lift pipe 5
An alkaline aqueous solution storage area 55 is formed between the outer peripheral surface of the base 4 and the inner peripheral surface of the absorption water tank 5. In this embodiment, sodium hydroxide is used as the alkaline aqueous solution.

An exhaust pipe 56 is provided on the ceiling wall 51, and exhaust gas staying in the space above the liquid level in the absorption water tank 5 is led out through the exhaust pipe 56. The discharged exhaust gas is introduced into an activated carbon adsorption tank 9 so that harmful substances such as a fluorine component and dioxin in the gas are adsorbed and removed. A washing tower 91 is interposed between the absorption water tank 5 and the activated carbon adsorption tank 9 so that the accumulated exhaust gas is brought into contact with the alkali aqueous solution in the washing tower 91 before the accumulated exhaust gas reaches the activated carbon adsorption tank 9. It may be. By doing so, the efficiency of removing hydrogen chloride and hydrogen fluoride in the retained exhaust gas is improved.

According to the above configuration of the absorption water tank 5 provided with the downcomer pipe 53 and the air lift pipe 54, the downcomer pipe 5 passes through the exhaust gas discharge hole 24 from the combustion decomposition device 1.
Exhaust gas W discharged into 3 depresses the liquid level in downcomer pipe 53 by the pressure, and is discharged in a gaseous state into gas-liquid contact area 534 from bubble hole 53a and an opening at the bottom.

The gas-liquid contact area 534 is formed by deriving the bubbles.
The inside becomes a gas-liquid two-phase flow, whereby the density of the liquid is reduced, so that the alkaline aqueous solution in the alkaline aqueous solution storage area 55 enters the gas-liquid contact area 534 from the bottom opening of the air lift pipe 54 due to the density difference, As a result, the gas-liquid contact area 534
Of the alkaline aqueous solution storage area 55, the alkaline aqueous solution in the gas-liquid contact area 534 is returned to the alkaline aqueous solution storage area 55 through the drain hole 54a, and this is repeated to Circulates between the gas-liquid contact area 534 and the alkaline aqueous solution storage area 55.

On the other hand, the bubbles of the exhaust gas W led out from the downcomer tube 53 come into contact with the aqueous alkali solution, whereby hydrogen chloride and hydrogen fluoride in the exhaust gas are neutralized and removed. Since a new alkaline aqueous solution is always supplied from the bottom opening of the air lift tube 54, the neutralization is efficiently performed.

The reaction formula of the above neutralization reaction is as follows. 2HCl + 2HF + 4NaOH → 2NaCl + 2NaF + 4H2O The storage tank 6 is for extracting and storing the alkali aqueous solution in the absorption water tank 5 when the alkalinity of the aqueous alkali solution in the absorption water tank 5 has decreased to a predetermined level due to the progress of the reaction. An alkaline stock solution for pH adjustment is supplied to the storage tank 6 from an alkali tank 8 as appropriate, and the remaining hydrogen fluoride and the like are neutralized by pH control. Further, the waste liquid in the storage tank 6 is appropriately supplied to the reaction tank 7.

The reaction tank 7 is for removing sodium fluoride from the waste liquid sent from the storage tank 6. In this reaction tank 7, salts B1 that react with sodium fluoride such as calcium chloride or calcium hydroxide, and a flocculant B2 are added while stirring the waste liquid by driving the stirring blade 71, and the reaction is performed by the following reaction. They try to produce calcium iodide. 2NaF + CaCl2 → 2NaCl + CaF2 2NaF + Ca (OH) 2 + 2HCl → CaF2 + NaCl + 2H2O The liquid containing calcium fluoride is sent to the downstream sedimentation tank 10, and the calcium fluoride precipitates when left standing, so that it is appropriately extracted. In addition, sedimentation tank 1
The supernatant liquid 0 is returned into the absorption water tank 5 by driving the pump 72, and can be circulated. An alkaline stock solution or water M from the alkaline tank 8 is added to the supernatant to adjust the pH.

By providing such an exhaust gas treatment device 50, it is possible to treat the exhaust gas and the waste liquid simultaneously with the combustion decomposition of the chlorofluorocarbon gas G1 in the combustion decomposition device 1, which is advantageous. For example, the concentrations of HCL and HF in the exhaust gas discharged through the exhaust pipe 56 are approximately 1 respectively.
It became 00 mg / Nm3 and 5 mg / Nm3 or less, indicating that harmful components in the exhaust gas W were almost removed. The concentration of dioxins in the gas derived from the activated carbon adsorption tank 9 is 0.1 mg / Nm3, and almost all dioxins are adsorbed and removed.

[0048]

According to the combustion apparatus for decomposing fluorocarbons according to claim 1, wherein the present invention, a burner provided in a circular cylindrical combustion vessel, the center line in the tangential direction of the inner peripheral wall surface of the cylindrical combustion chamber Since it is arranged so as to extend, the fluorocarbon, the auxiliary agent, and the oxygen-containing gas supplied from the burner into the combustion vessel are guided by the inner peripheral wall surface and swirl in the vessel to form a swirling flow. Due to the formation of this swirling flow, the mixing of CFCs with the auxiliary agent and the oxygen-containing gas is performed uniformly, thereby promoting the combustion of the CFCs and the auxiliary agent, and increasing the combustion temperature to the decomposition temperature of the CFCs or higher. , CFCs are surely decomposed by combustion, and as a result, the ratio of CFCs / combustion agent can be increased, which is advantageous in detoxifying CFCs at low cost.

Since an exhaust gas treatment device for treating exhaust gas generated by the combustion decomposition of chlorofluorocarbon is provided on the downstream side of the combustion vessel, the exhaust gas is detoxified by treating the exhaust gas from the combustion decomposition device with the exhaust gas treatment device. This is effective in reliably preventing environmental pollution due to harmful substances produced secondarily after burning and decomposing CFCs.

[0050] Then, the exhaust gas discharged from the combustion cracker is fed to the downcomer pipe, depress the liquid level in the downcomer pipe by the exhaust gas pressure is released from the bottom opening in the bubble state, the outer peripheral surface of the downcomer pipe It rises through the gas-liquid contact area between the inner peripheral surface of the air lift pipe. Since the exhaust gas comes into contact with the neutralizing solution in a bubble state as described above, the contact area of the exhaust gas with the neutralizing solution increases, and the neutralizing treatment of the exhaust gas is performed reliably and efficiently.

Since the density of the liquid in the gas-liquid contact area decreases due to the generation of the air bubbles, the neutralizing liquid in the absorption tank enters the gas-liquid contact area through the bottom opening of the air lift pipe, and the gas in the gas-liquid contact area enters the gas-liquid contact area. The liquid in a liquid mixed state is pushed upward and returned from the upper overflow section into the absorption water tank, whereby the neutralized liquid circulates and moves. Therefore, a new neutralization liquid in the absorption water tank is always supplied into the gas-liquid contact area, which is advantageous in reliably performing the neutralization treatment of the exhaust gas.

According to the second aspect of the present invention, a neutralization tank is provided between the absorption water tank and the sedimentation tank to neutralize the liquid discharged from the absorption water tank. The unneutralized hydrogen fluoride remaining in the absorption water tank is neutralized in the neutralization tank, which is effective in reliably performing the neutralization treatment.

According to the apparatus for decomposing and decomposing freon according to the third aspect of the present invention, since a pipe for circulating the supernatant of the sedimentation tank to the absorption water tank is provided, the pH of the supernatant is adjusted. It is returned to the absorption water tank as a neutralizing solution through a pipe, which is convenient for effectively using the neutralizing solution.

According to the CFC combustion decomposing apparatus of the fourth aspect of the present invention, the exhaust gas present in the gas phase space between the outer peripheral surface of the air lift pipe and the inner peripheral surface of the absorption water tank is supplied. Since the gas washing tower is provided, harmful substances such as hydrogen fluoride and dioxins contained in the exhaust gas are absorbed and removed by the treatment in the gas washing tower, and the harmful substances are released to the outside air. Is effective in reliably preventing

According to the fifth aspect of the present invention, the flue gas present in the gas phase space between the outer peripheral surface of the air lift pipe and the inner peripheral surface of the absorption water tank is supplied. Since the activated carbon adsorption tank is provided, the harmful substances such as hydrogen fluoride and dioxins in the exhaust gas that have accumulated in the above space are adsorbed and removed by the treatment in the activated carbon adsorption tank, and the harmful substances are released to the outside air. Is effective in reliably preventing

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a first embodiment of a chlorofluorocarbon gas combustion decomposition apparatus according to the present invention, in which (A) is an explanatory view in a side sectional view, and (B) is an AA line view in (A). is there.

FIG. 2 is a graph showing a relationship between a combustion load rate and a CFC decomposition rate.

FIG. 3 is a graph showing a relationship between a ratio of chlorofluorocarbon / methane and a decomposition ratio of chlorofluorocarbon.

FIG. 4 is an explanatory view showing a second embodiment of the chlorofluorocarbon gas combustion decomposition apparatus according to the present invention, wherein FIG. 4 (a) is a side sectional view, and FIG. 4 (b) is a line BB of FIG. is there.

FIG. 5 is an explanatory diagram showing an exhaust gas treatment device provided downstream of the combustion decomposition device.

[Description of Signs] 1 Combustion decomposer 2 Combustion vessel 21 First burner 22 Second burner 23 Combustion chamber 24 Exhaust gas discharge hole 25 Peripheral wall surface 3 Gas mixer 4 Oxygen-containing gas mixer 5 Absorption water tank 51 Ceiling wall 52 Communication hole 53 Downcomer pipe 53a Bubble hole 54 Air lift pipe 534 Gas-liquid contact area 54a Drainage hole (overflow part) 55 Alkaline aqueous solution storage area 56 Exhaust pipe 6 Storage tank 7 Reaction tank 71 Stirrer blade 8 Alkaline tank 9 Activated carbon adsorption tank 10 Sedimentation tank G ′ Oxygen-containing raw material gas G Raw material gas G1 Freon gas G2 Combustion agent B1 Salts such as calcium chloride or calcium hydroxide B2 Coagulant M Water

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-51611 (JP, A) JP-A-6-109224 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 53/70 F23G 7/06 ZAB

Claims (5)

(57) [Claims] 1. A chlorofluorocarbon-combustion decomposer for decomposing a chlorofluorocarbon-containing gas by subjecting the chlorofluorocarbon-containing gas to a combustion aid comprising hydrogen or a gaseous linear hydrocarbon and an oxygen-containing gas. There is provided a cylindrical combustion vessel, and a burner for supplying chlorofluorocarbon, a combustion aid, and an oxygen-containing gas into the combustion vessel. The burner has a center line tangent to the inner peripheral wall surface of the cylindrical combustion vessel. An exhaust gas treatment device that is disposed so as to extend in the direction and that treats exhaust gas generated by the combustion decomposition of chlorofluorocarbon is provided on the downstream side of the combustion vessel, and the exhaust gas treatment device absorbs a decomposition product of chlorofluorocarbon.
Absorption water tank capable of retaining neutralizing solution to be neutralized, and this absorption water tank
The dissolved salt containing fluorine obtained by neutralization with
And a sedimentation tank for sedimenting the precipitated salt.
And the absorption tank receives the exhaust gas from the top.
A downcomer tube with an open bottom and this downcomer tube
With an open bottom and an upper
And an air lift pipe provided with a bar flow portion . 2. A The absorbent water tank, a combustion decomposition of Freon according to claim 1, characterized in that the neutralization tank neutralizing the liquid derived from the absorption water tank is provided between the reaction vessel apparatus. 3. Freon combustion decomposition apparatus according to claim 1 or 2, wherein the supernatant of the sedimentation tank to circulate and supply pipe to the absorbing water tank is provided. 4. A gas washing tower to which exhaust gas existing in a gas phase space between an outer peripheral surface of the air lift pipe and an inner peripheral surface of the absorption water tank is provided. Item 4. A chlorofluorocarbon combustion and decomposition device according to any one of Items 1 to 3 . 5. An activated carbon adsorption tank for supplying exhaust gas existing in a gas phase space between an outer peripheral surface of the air lift pipe and an inner peripheral surface of the absorption water tank is provided. Item 4. A chlorofluorocarbon combustion and decomposition device according to any one of Items 1 to 3 .