JPH03295570A - Plasma decomposition processing method for halogenated organic compound - Google Patents

Abstract

PURPOSE:To prevent the generation of molecular halogen by executing the plasma decomposition processing by controlling a raw material supply device so that a ratio of carbon, oxygen, chlorine, fluorine, bromine and hydrogen atoms in a raw material supplied in a unit time satisfies two conditional expression. CONSTITUTION:By flow controllers 26-30, argon gas, hydrogen gas, oxygen gas, aqueous vapor, and halogenated organic compound vapor are supplied so that a condition 1 and a condition 2 are satisfied by a computer 38 through pipings 31, 32. 2XC<XO (condition 1) and 2(XO-2KC+XCl+DF+XBr<XH (condition 2), and in this regard, X denotes the respective mol numbers in a raw material supplied per unit time. In a plasma torch 33, the raw material is decomposed like an atom and a part thereof forms plasma by being ionized, exhausted gas is subjected to heat recovery by a heat recovery device 34 and allowed to pass through a bubbling tank 35 and halogen hydride of hydrochloric acid, fluoric acid, bromic acid, etc., is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for decomposing a halogenated organic compound using plasma.

(Prior Art) The release of halogenated organic compounds into the atmosphere is said to be a factor in the destruction of the stratospheric ozone layer.

(M, J, Molina and F, S, R
otiland, Nature 249°pp, 8
10-812) Destruction of the ozone layer is thought to significantly change the environment on earth because it reduces the absorption of ultraviolet rays from sunlight. Therefore, in order to reduce the amount of halogenated organic compounds emitted, research and development are being conducted on the development of substitutes for halogenated organic compounds, the recovery and reuse of halogenated organic compounds, and the decomposition and immobilization of halogenated organic compounds. In order to prevent the release of halogenated organic compounds that already exist in fabrics and those that will be produced in the future,
It is necessary to decompose and immobilize saponified organic compounds.

There are two methods for decomposing and immobilizing halogenated organic compounds: a high-temperature method in which the halogenated organic compound is decomposed with high-temperature plasma, and a low-temperature method in which the halogenated organic compound is decomposed at room temperature using a reagent. The low-temperature method requires a large amount of reagents, has a slow processing speed, and requires huge equipment, which is expensive.

On the other hand, high-temperature methods can be expected to achieve high processing speeds by using plasma with high energy density. Mr. Wakabayashi (T, W
akabayashi, Proc, 9th Int
, Sympo.

Plasma chew, pp, Lllll (19
The method used by 89) et al. is illustrated in FIG. Argon gas is supplied by the flow controller (1), hydrogen gas or oxygen gas is supplied by the flow controller (2), water vapor evaporated by the steam evaporator (5) together with argon carrier gas provided by the flow controller (3), and the flow A raw material mixed with argon gas supplied by the controller (4) and a halogenated organic compound evaporated by the halogenated organic compound evaporator (6) is supplied to the high frequency plasma torch (8) through the flow meter (7). . In the plasma torch, these raw materials are decomposed into atoms and some of them are ionized to form plasma. After cooling the plasma in a cooler (9), a soot-like product is collected in a dust collector (10). The gas after dust collection is passed through a bubbling tank (11) containing an aqueous sodium hydroxide solution and an adsorption tower (12) filled with quicklime to remove halogen hydrides such as hydrochloric acid. In order to compensate for pressure loss in the bubbling tank and adsorption tower, exhaust is performed using a blower (13).

The method using plasma has a high processing speed despite the small volume of the reactor, so the burden of equipment disposal is small. However, a large amount of electric power is required to generate plasma. Therefore, it is desired to improve energy efficiency by recovering the used energy.

Furthermore, it is necessary to prevent chlorine, fluorine, and bromine, which have been decomposed into atoms in the plasma, from recombining with carbon in the plasma tail flame region or downstream region, and thereby producing halogenated organic compounds again. However, the method shown in FIG. 5 cannot prevent the regeneration of halogenated organic compounds due to the following two problems. First, hydrogen and oxygen cannot be supplied at the same time due to equipment limitations, and hydrogen or oxygen is not supplied at the same time as water vapor. Second, the feed rates of water vapor and halogenated organic compounds are not tightly controlled. Therefore, even if it is once dissociated into atoms in plasma, a gaseous halogenated organic compound or a soot-like polymer may be generated again.

Therefore, a dust collector (10) is required. In such a case, not only will the original purpose of the decomposition process not be achieved, but even if a heat recovery device is installed upstream of the dust collector (10), stable operation of the heat recovery device will be difficult due to the soot-like products. be.

In order to prevent halogenated organic compounds from being generated in the plasma tail or downstream region, a method can be considered in which a large amount of water is blown into the plasma tail to fix atomic chlorine, fluorine, or bromine in the water. but.

With this method, recovery of waste heat cannot be expected at all. In other words, the electric power used to generate and maintain plasma is wasted in the form of low-energy-density heat.

In this process, it is desired to efficiently treat exhaust gas in the bubbling tank. For this purpose, the chlorine, fluorine, and bromine atoms to be treated must exist as hydrophilic molecules such as hydrogen chloride, hydrogen fluoride, and hydrogen bromide, rather than molecular halogen gases that have a small solubility limit in water. desired. If molecular halogen gas is generated, it is necessary to frequently replace the water in the bubbling tank, and an absorption tower (12) is required as shown in FIG.

(Problems to be Solved by the Invention) In view of the current situation, the present invention aims to recover heat by guiding high-temperature exhaust gas to a heat recovery device without rapidly cooling the gas after plasma treatment and preventing recombination of halogenated organic compounds. The purpose is to prevent soot-like deposits from adhering to the heat recovery device so as not to reduce the efficiency of the device, and to perform stable heat recovery in the plasma decomposition process.

A further object of the present invention is to prevent the generation of molecular halogens, generate them as hydrophilic molecules such as hydrogen chloride, hydrogen fluoride, and hydrogen bromide, and efficiently remove them in a bubbling tank.

(Means for Solving the Problems) The present inventors have conducted various experiments and studies to achieve the above object, and as a result, have arrived at the present invention.

In other words, firstly, in the plasma decomposition process of halogenated organic compounds, a heat recovery device is installed and the heat recovery efficiency is measured. was found to decrease. Moreover, this soot-like deposit was a polymer of halogenated organic compounds.

Furthermore, it has been found that when raw materials decomposed into atoms in plasma are recombined into gaseous halogenated organic compound polymers during the cooling process, some of them become soot-like halogenated organic compound polymers. Ta. That is, when a soot-like halogenated organic compound polymer is produced, a gaseous halogenated organic compound such as CF is produced in the exhaust gas. Therefore, it has been found that the formation of a soot-like halogenated organic compound polymer can be monitored by detecting the formation of a gaseous halogenated organic compound.

Using an exhaust gas mass spectrometer, we found a raw material composition that does not generate gaseous halogenated organic compounds in the exhaust gas. This is also a condition under which soot-like halogenated organic compound polymers are not produced.

This is condition 1.

Similarly, the relationship between the raw material composition and the production of molecular halogens was investigated, and conditions were found under which molecular halogens such as CQ2 were not produced. That is, this is condition 2.

The first invention was made based on the above-mentioned knowledge, that is, the present invention provides a method for supplying a single type of halogenated organic compound and an additive into a plasma for decomposition treatment. The raw material supply device is controlled so that the ratio of carbon, oxygen, chlorine, fluorine, bromine, and hydrogen atoms in the raw material satisfies the following two conditional expressions, and the plasma decomposition treatment of the halogenated organic compound is performed.At the same time, the plasma tail is This is a plasma decomposition treatment method for halogenated organic compounds, which is characterized in that a heat recovery device is installed downstream from a flame section to perform heat recovery.

2xo<xo (condition 1) 2(XO-2XC)+XOQ crushed+x8r<XH (condition 2) where XC is the number of moles of carbon atoms in the raw material supplied per unit time.

XO is the number of moles of oxygen atoms in the raw material supplied per unit time.

XCl is the number of moles of chlorine atoms in the raw material supplied per unit time.

X is the number of moles of fluorine atoms in the raw material supplied per unit time.

XBr is the number of moles of bromine atoms in the raw material supplied per unit time.

XH is the number of moles of hydrogen atoms in the raw material supplied per unit time.

Here, the halogenated organic compound is ccQ3F (Freon 1
1), ccQ2F2 (Freon 12), C2Cl2a F
s (Fronje 13).

Compounds commonly called fluorocarbons such as CzCj2zF4 (Freon 114) and czcQFs (Freon 115), CF
It includes compounds commonly called halons such as 2BrC4 (halon 1211), CF, Br (halon 1301), and CF4Br2 (halon 2402). Furthermore, the volatile organic compound C2(4,1(,C,CQ,,CC4
,,C2CQ3H,,C2CQ2H4,C2CQH,,
C(,Q)I,,trans-1,2-C2CQ2H,
, cis-1, 2-C2CQ2H2, Cz C(lz
l (including z, etc.) Furthermore, 1 , 1 , 2-C2C
In addition to containing organic compounds such as Q2H4,1,1,-C, Cl2H, etc., it also includes powders of these polymers, commonly called Teflon, with a particle size of about 5 .mu.m. Further, the additives used in the present invention are water or steam, hydrogen, and oxygen.

The halogenated organic compound and additives to be treated are collectively referred to as raw materials.

Furthermore, the second invention was achieved by decomposing not a single type of halogenated organic compound but a mixture such as a mixture of CCQ3F and CHCQ3 as a decomposition product in the halogenated organic compound decomposition process.

That is, the first invention is effective when the composition of the object to be treated is known, but when the composition of the object to be treated is unknown, the supply ratio of raw materials cannot be determined in advance.

However, in reaching the first invention, if condition 1 is not satisfied, the exhaust gas contains halogenated organic compounds such as CF4, and if condition 2 is not satisfied, molecular compounds such as Cl2 are contained in the exhaust gas. It was discovered that it contained halogens. Therefore, we discovered that by mass spectrometry of the exhaust gas and feeding it back, it is possible to control the raw material supply rate so that conditions 1 and 2 are satisfied even if the composition of the raw material is unknown in advance.

The second invention was made based on the above knowledge, and the present invention provides a method for supplying halogenated organic compounds and additives into plasma for decomposition treatment, in which gas after plasma decomposition treatment is sampled. When a gaseous halogenated organic compound is detected in the sampled gas, the proportion of oxygen contained in the raw material is increased, and when molecular halogen gas is detected in the sampled gas, the proportion of hydrogen contained in the raw material is increased. Plasma decomposition treatment of a halogenated organic compound, characterized in that the plasma decomposition treatment of the halogenated organic compound is performed by increasing the ratio of It's a method.

(for production) The present invention will be explained in detail below.

The apparatus used in the first invention is shown in FIG. The flow controller (26) controls the argon gas from the argon cylinder (21), the flow controller (27) controls the hydrogen gas from the hydrogen tank (22), the flow controller (28) controls the oxygen gas from the oxygen tank, and the flow controller (29) by steam evaporator (24
) and the flow controller (3
0), the halogenated organic compound vapor supplied from the halogenated organic compound supply device (25) is connected to the piping (31,
32). When using hydrogen and oxygen at the same time, prepare two or more piping systems and use a plasma torch (
Up to 32), it is desirable to separate and supply hydrogen and oxygen. Also, unlike FIG. 5, independent flow controllers are used for water vapor and halogenated organic compounds, and their flow rates are independently controlled. In order to automatically control this, it is sufficient to simply use a mass flow controller as a flow controller, but for example, a water vapor evaporator (2
4) The amount of water vapor generated may be unstable. Therefore, a signal indicating the flow rate in the flow controller is connected to the computer (38) through the line (37), and the computer instructs the flow controller to support the double amount through the line (39) so that conditions 1 and 2 are satisfied. This is desirable.

In the plasma torch (33), the raw material is decomposed into atoms and some of them are ionized to form plasma.

The gas exhausted from the plasma torch is collected using a heat recovery device (34
) and passing it through a bubbling tank (35) to remove halogen hydrides such as hydrochloric acid, hydrofluoric acid and bromic acid. Blower (36) to compensate for pressure loss in the bubbling tank
Exhaust the air.

The halogenated organic compound treated in the present invention is CCQ3F.
(Freon 11), CCl2F2 (7C1-12), C
zCQaFa (Near 113), C, Cl2F4
(70 114), C2CQFs ('7 Cl 11
5) Compounds commonly called fluorocarbons such as CF z B
r Contains compounds commonly called halons such as C11 (halon 1211), CF3Br (halon 1301), CF, Br, (halon 2402), etc. Furthermore, volatile organic compounds C, Cf13H, C, CL, CCQ4
, C2cn, C3, C2CQ, H,, C2CQH3,
CCQH3, trans-1,2-C2cQ, C2,c
Also includes is-1,2-C2C1112H□, C2CQ2H2, etc. Furthermore, 1, 1, 2-C.

It also includes organic compounds such as CQ2H, 1-C, and CQ2H.

In addition, it also includes powders of these polymers, commonly known as Teflon, with a particle size of around 5 μm.

Here, from the viewpoint of supply rate management, the halogenated organic compounds to be decomposed can be classified into two types. The first case is the case where four times the number of carbon atoms contained in the unit weight is equal to the total amount of halogen atoms such as chlorine, fluorine, and bromine contained in the unit weight (hereinafter referred to as the first case). . The second case is when the number of carbon atoms contained in the unit weight is four times greater than the total amount of halogen atoms such as chlorine, fluorine, bromine, etc. contained in the unit weight (hereinafter referred to as the second case). .

A schematic diagram of an apparatus for plasma decomposition of polymers is shown in FIG. In this case, the halogenated organic compound supply device (25) and its flow controller (3) shown in FIG.
0), it has a gas flow controller (40) for conveying the powder, and the pipe (40) is connected from the powder supply device (41) to
42) to the plasma torch (33). At this time, the powder feeder (41) must be able to control the feeding speed.

The powder supply speed is controlled by the computer (38) and the signal line (3).
7, 39).

The additives used in the present invention are water or steam, hydrogen, and oxygen. When a halogenated organic compound is used first, two or more of these containing hydrogen must be used as additives. In the second case, it is not possible to choose only oxygen and only hydrogen as additives, but only water or steam. Furthermore, in the second case, if only water or steam is used, condition 2 can be satisfied at any supply rate, so only condition 1 needs to be controlled.

The plasma used in the present invention is preferably a thermal plasma6 because the supplied halogenated organic compound does not dissociate into atoms in a cold plasma.

Although argon is normally used as the gas for generating plasma, it is desirable to use large amounts of oxygen, hydrogen, and water vapor (or water) in this process. This is because, as shown in Conditions 1 and 2, if these are used in large quantities, a large amount of halogenated organic compounds can be treated. therefore.

If possible, use only steam (or water) without argon,
It is most desirable to generate plasma with water vapor and hydrogen, water vapor and oxygen, or hydrogen and oxygen.

The downstream part from the tail flame part of the plasma refers to the downstream part where the heat recovery device is not damaged by the plasma.

It is desirable that the material of the heat recovery device has excellent acid resistance.

The basic aqueous solution in the bubbling tank (35) needs to be basic. That is, it is desirable to contain as much hydroxyl ion (OH-) as possible. Furthermore, although sodium ions (Na'') and the like can be used as cations, it is desirable to include calcium ions (Ca 2 + ).

This is because fluorine absorbed from the gas is recovered as CaF2. Even if heat is recovered, the water level in the bubbling tank may drop due to the heat, so it is desirable to automatically supply water using a float to keep the water level constant. Furthermore, in the bubbling tank, hydrochloric acid, hydrofluoric acid, and bromic acid are constantly absorbed, so hydroxide ions in the aqueous solution decrease and hydrogen ions increase. Therefore, in order to keep the hydroxide ion concentration constant, it is desirable to measure the pH of the aqueous solution and automatically add a basic substance when the hydroxide ion concentration decreases.

Further, as a device for removing the precipitates in the bubbling tank, a method using a circulator having a filter is possible. Although it is possible to use one removing device intermittently, it is preferable to use a plurality of removing devices alternately to alternately remove the precipitate removed from the aqueous solution with the filter.

The apparatus used in the second invention is shown in FIG. In this device, a part of the exhaust gas after decomposition is guided to a mass spectrometer (44) through a sampling tube (43), and the signal from the mass spectrometer is sent to a computer (38) through a line (45). The computer determines whether there is a gaseous halogenated organic compound or a molecular halogen gas.

Here, if a halogenated organic compound is detected, condition 1 is not satisfied, so the right side of condition 1 (XO
) is increased, but the left-hand side (Xc) of condition 1 is decreased.

In other words, increasing the proportion of oxygen contained in the raw material means
Through the signal line (39), a signal is given to the oxygen flow controller (28) to increase the oxygen supply rate, but a signal is given to the water vapor flow controller (29) to increase the water vapor supply rate. and providing a signal to the compound flow controller (30) to reduce the feed rate of the halogenated organic compound.

The gaseous halogenated organic compound used in the criteria for Condition 1 is CCM4. CCM,F2,CCQF,,c
FC, CM, C2CQ, F, C2CQ, F, etc. For example, when the halogenated organic compound to be decomposed is a single type of CCM4, the raw material does not contain fluorine or bromine atoms before decomposition.
As a criterion, it is necessary to use at least one molecule that does not contain a fluorine atom and a bromine atom, such as CC. Similarly, when the halogenated organic compound to be decomposed is, for example, a single type of CF4, the raw material does not contain chlorine atoms or bromine atoms before decomposition. It is necessary to use at least one molecule that does not contain atoms. therefore,
If we use the same criteria when replacing halogenated organic compounds that must be frequently decomposed, at least molecules that do not contain fluorine and bromine atoms; molecules that do not contain chlorine and bromine atoms; and molecules that do not contain chlorine and fluorine atoms It is necessary to use three or more of these as criteria for judgment. If possible, it is preferable to use as many types of molecules as criteria.

On the other hand, if molecular halogen gas is detected, condition 2 is not satisfied, so either the right side of condition 2 is increased or the left side of condition 2 is decreased.

In other words, increasing the proportion of hydrogen contained in the raw material means
Through the signal line (39), a signal is given to the hydrogen flow controller (27) to increase the hydrogen supply rate, or a signal is given to the oxygen flow controller (28) to decrease the oxygen supply rate. Furthermore, when the halogenated organic compound to be treated is the second one, it is also effective to reduce the supply rate of the halogenated organic compound by giving a signal to the flow controller (30) for the halogenated organic compound.

The molecular halogen gas used as the criterion for condition 2 is Cl22, F2, Br2, etc. Furthermore, complex molecules such as CΩF can also be used as a criterion. If the same criteria are used when frequently changing halogenated organic compounds to be decomposed, at least Cρ2, F
It is desirable to use three or more of 2 and Br2 as the criterion. If possible, it is preferable to use as many types of molecules as criteria.

It is desirable that the sampling position of the exhaust gas be close to the plasma in order to increase the response speed, but it is desirable to avoid the plasma tail flame region because the reaction is not yet completed due to the extremely high temperature. Conversely, when sampling at the outlet of the bubbling tank (3S), the response speed is delayed.

In the apparatus used in the second invention, it is not necessarily necessary to equip all raw material supply apparatuses with a flow controller. This one
An example is shown in FIG. In Figure 4, the plasma torch (33)
A water plasma torch is used. In the water plasma torch, liquid water is supplied to the plasma torch, and a part of the supplied water is turned into plasma, but the rest cools the plasma torch and is recovered by the water circulation pump (48). At this time, the amount of water supplied to the plasma is determined by the flow meter (4) on the inlet side.
6) and the outlet flow meter (47), but cannot be controlled. However, if a hydrogen gas flow controller (27) and an oxygen flow controller (28) are provided, the control shown in the second invention is possible. In addition to this combination, it is possible to increase the proportion of oxygen or hydrogen by combining an oxygen flow controller (28) and a halogenated organic compound flow controller (30).

Examples of the present invention are shown below.

(Example 1) Plasma decomposition of a halogenated organic compound was performed using the apparatus shown in FIG. A high frequency plasma torch was used as the plasma torch (33). Frequency is 4 MHz
It is. Real-bon plasma was generated using a high-frequency plasma torch, raw materials were supplied into the plasma, and the heat recovery was allowed to stabilize for 10 minutes, and the amount of heat was measured 10 minutes and 1 hour after the start of supply. The power supplied to the high frequency power source was 70 kV, and the heat recovery device installed downstream of the plasma recovered 18 kW after 10 minutes. The heat recovery reduction rate (R) was determined from the heat recovery amount after 1 hour. Table 1 shows the relationship between the raw material ratio and the heat recovery reduction rate after 1 hour when the decomposition products are CCQ and F. Here, the heat recovery reduction rate (R
) is defined by the following formula.

It can be seen from Table 1 that Condition 1 must be satisfied in order for the heat recovery reduction rate (R) to become 0.

In addition, if 1 condition 1 is not satisfied, CC
Q2F2, CCQF, CF4, C2CQ4. C2C
Q3F, C2CQ, F3, etc. were detected in the exhaust gas, but were not detected when Condition 1 was satisfied. C2CQ3F1, CCQF3, C2HC, etc. as processed materials
Similarly, when Q4 was used, the heat recovery rate decreased when the conditions were not met.

Furthermore, by analyzing the gas after passing through the bubbling tank, it became clear that when Condition 2 was not satisfied, chlorine gas was no longer absorbed as time passed.

Conversely, when conditions 1 and 2 were satisfied at the same time, it was possible to operate for a long time. In particular, since there was no molecular halogen gas in the gas after passing through the bubbling tank, an adsorption tower was not required.

(Example 2) Plasma decomposition treatment of a halogenated organic compound was performed using the apparatus shown in FIG. Plasma torch (33)
A DC plasma device was used. The plasma torch is a commercially available direct current plasma torch for thermal spraying. After generating argon plasma, water vapor is released from the spray powder supply nozzle.
After hydrogen or oxygen was supplied and the DC power was set to 40 kW, the halogenated organic compound was supplied from the nozzle. At this time, the amount of heat exchanged was measured 10 minutes and 1 hour after the start of supply. After 10 minutes, the heat recovery device
4kW was recovered. The heat recovery reduction rate (R) after 1 hour was determined. Even when DC plasma was used, if Condition 1 was satisfied, the heat recovery reduction rate (R) was O based on the heat recovery amount.

Furthermore, when Condition 2 was not satisfied, molecular halogenated gas began to be detected downstream of the bubbling tank as the operating time progressed. However, when Condition 2 was satisfied, no molecular halogen gas was detected.

(Example 3) Plasma decomposition treatment of a halogenated organic compound was performed using the apparatus shown in FIG. Plasma torch (33)
In this study, a high-frequency plasma torch was used to decompose a polymer of halogenated organic compounds.

At this time, in order to supply the polymer to the plasma, an average particle size of 5
The powder was ground to a μ value, and the ground powder was fed using a powder feeder. A plasma was generated with argon and water vapor, and the polymer powder was fed at a feed rate of 3 g/min. Condition 1: Low water vapor supply rate
When condition 1 was not satisfied, halogenated organic compounds were observed in the exhaust gas.When condition 1 was satisfied, no halogenated organic compounds were observed in the exhaust gas.

Furthermore, when condition 2 was not satisfied, molecular halogen gas was detected downstream of the bubbling tank as the operating time progressed. However, when Condition 2 was satisfied, no molecular halogen gas was detected.

(Example 4) Plasma decomposition treatment of a halogenated organic compound was performed using the apparatus shown in FIG. CCQ as a decomposable product,
A 1=1 mixture of F and CHCQ3 was used.

First, the mass spectrometer (44) was used as shown in FIG. 1 without using the analysis function. At this time, assuming a mixing ratio of 1:1, hydrogen and oxygen were supplied so as to satisfy Conditions 1 and 2. At the beginning of operation, molecular halogen gas was detected in the exhaust gas, but no recombined halogenated organic compounds were detected, but as time passed, halogenated organic compounds and molecular halogen gas were no longer detected.

In order to investigate the cause of this, we sampled the supply system piping of the processed material and conducted mass spectrometry.
As the concentration of CHCQ increased, the concentration of CHCQ gradually increased. In other words, it has become clear that since CCU3F with a high vapor pressure is initially supplied and then CHCQ3 with a low vapor pressure is supplied, the mixing ratio changes over time even when controlled by a mass flow meter.

Therefore, the exhaust gas was constantly analyzed using a mass spectrometer (44) and decomposed using a feedback function. After continuous operation for one hour, no halogenated organic compound was observed in the exhaust gas. The same was true for molecular halogen gas.

Furthermore, C2Q3F, C2CQ, F3, CCQF, ,C
A suitable mixture of 2HC et al. and CCQ4 was decomposed. At this time as well, no halogenated organic compounds were detected in the exhaust gas even though continuous operation was performed by applying feedback from the mass spectrometer. Likewise, no bimolecular halogen gas was detected.

(Example 5) A halogenated organic compound was decomposed using the apparatus shown in FIG. Here is the plasma torch (33)
A thermal spray water plasma torch developed in Czechoslovakia was used. After generating water plasma, hydrogen was supplied from a thermal spray powder supply nozzle to adjust the DC power to 170% L, and then a halogenated organic compound was supplied from the nozzle.

At this time, the amount of heat exchanged was measured 10 minutes and 1 hour after the start of supply. After 10 minutes, the heat recovery device installed downstream of the plasma recovered 35kW. In this case, since the steam evaporator (24) used in the apparatuses shown in FIGS. 1, 2, and 3 was not used, the overall energy efficiency was excellent.

(Effects of the Invention) As described above, according to the present invention, high-temperature exhaust gas is guided to the heat recovery device while not rapidly cooling the gas after plasma treatment and preventing recombination of halogenated organic compounds. In order not to reduce the efficiency of the plasma decomposition process, it has become possible to prevent soot-like deposits from adhering to the heat recovery device and to perform stable heat recovery during the plasma decomposition process.

Further, according to the present invention, it has become possible to prevent the generation of molecular halogens, generate them as hydrophilic molecules such as hydrogen chloride, hydrogen fluoride, and hydrogen bromide, and efficiently remove them in a bubbling tank.

As a result of the above, it has become possible to industrially implement a plasma decomposition treatment process for halogenated organic compounds, and this will greatly contribute to industrial development.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the apparatus used in Example 1. FIG. 2 is a schematic diagram of the apparatus used in Example 3. FIG. 3 is a schematic diagram of the apparatus used in Example 4. FIG. 4 is a schematic diagram of the apparatus used in Example 5. FIG. 5 is a schematic diagram of the apparatus used by Kurugai et al. The devices indicated numerically in these drawings are: 1: Argon gas flow controller 2: Hydrogen gas or oxygen gas flow controller, 3: Steam carrier gas flow controller, 4: Halogenated organic compound carrier gas flow controller, 5: Steam evaporator, 6: Halogenated organic compound supply Device, 7: Flowmeter, 8
: Plasma generator, 9: Cooling device, 10: Dust collector, 11
: Bubbling tank. 12: adsorption device, 13 nib blower, 21: argon cylinder, 22: hydrogen cylinder, 23: oxygen cylinder, 24: steam generator, 25: halogenated organic compound supply device. 26: Argon gas mass flow controller, 27:
Hydrogen gas mass flow controller, 28: Oxygen gas mass flow controller, 29: Water vapor mass flow controller, 30: Halogenated organic compound mass flow controller, 31: yX material supply pipe, 32: Raw material supply pipe, 33: Plasma torch, 34: Heat recovery device , 35
: Bubbling tank, 36: Blower, 37: Flow rate signal line, 38: Process control computer, 39: Flow rate instruction signal line, 40: Powder carrier gas mass flow controller, 41: Powder supply device, 42: Powder supply piping, 4
3: Exhaust gas sampling tube, 44: Mass spectrometer, 45
: Mass spectrometry signal line, 46: Torch supply water flow meter, 47
:Torch return water flow needle, 48:Water circulation device, 49:Water supply

Claims (2)

[Claims] (1) In the method of supplying a single type of halogenated organic compound and additives into plasma for decomposition treatment, the ratio of carbon, oxygen, chlorine, fluorine, bromine, and hydrogen atoms in the raw materials supplied per unit time is The raw material supply device is controlled to satisfy the following two conditional expressions to perform plasma decomposition treatment of halogenated organic compounds, and at the same time, a heat recovery device is installed downstream from the tail flame part of the plasma to perform heat recovery. Characteristic plasma decomposition treatment method for halogenated organic compounds. 2X_C<X_O (condition 1) 2(X_O-2X_C)+X_C_l+X_F+X_B
_r<X_H (Condition 2) Here, X_C is the number of moles of carbon atoms in the raw material supplied per unit time. X_O is the number of moles of oxygen atoms in the raw material supplied per unit time. X_C_l is the number of moles of chlorine atoms in the raw material supplied per unit time. X_F is the number of moles of fluorine atoms in the raw material supplied per unit time. X_B_r is the number of moles of bromine atoms in the raw material supplied per unit time. X_H is the number of moles of hydrogen atoms in the raw material supplied per unit time. (2) In the method of supplying halogenated organic compounds and additives into plasma for decomposition treatment, gas after plasma decomposition treatment is sampled, and gaseous halogenated organic compounds are detected in the sampled gas. Sometimes, the proportion of oxygen contained in the raw material is increased, and when molecular halogen gas is detected in the sampled gas, the proportion of hydrogen contained in the raw material is increased, and the halogenated organic compound is subjected to plasma decomposition treatment. A method for plasma decomposition treatment of halogenated organic compounds, characterized in that a heat recovery device is installed downstream from the tail flame part of the plasma to perform heat recovery.