JP2003120919A - Thermal decomposition method and thermal decomposition apparatus for n2o - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal decomposition apparatus for N2 O capable of completely decomposing N2 O by adopting a comparatively simple means. SOLUTION: This thermal decomposition apparatus 1 for N2 O includes a conduit 2, a first supply part 5 for supplying N2 O into the conduit 2, a discharge device 46 for forming an arc discharge area A2 for circulating N2 O, a second supply part 11 for supplying propane into the conduit 2, and a combustion part 15 for burning the propane to produce a thermal atmosphere for decomposing N2 O.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermal decomposition method and thermal decomposition apparatus for N ₂ O (nitrogen monoxide, nitrous oxide, laughter).

[0002]

2. Description of the Related Art N ₂ O is chemically extremely stable and poor in reactivity, and thermal decomposition starts at about 800 ° C., but its decomposition efficiency is extremely low. Therefore, until now, the industrial treatment technology of N ₂ O has not been established.

[0003]

However, N ₂ O
Is used as a anesthetic in hospitals in relatively large amounts, so establishment of its industrial treatment technology is a necessary matter for environmental hygiene.

[0004]

The present invention SUMMARY OF] is to provide a thermal cracking process and the thermal decomposition apparatus of the N ₂ O which is adapted to completely decompose N ₂ O by employing a relatively simple means To aim.

According to the present invention to achieve the above object,
Hydrocarbon, hydrogen, alcohol, ether, aldehyde,
Ketones, esters, carboxylic acids, fats and oils, phenols,
A thermal decomposition method of N ₂ O is provided, in which at least one combustible substance selected from ammonia, amine and aniline is combusted, and N ₂ O is decomposed in a thermal atmosphere accompanying the combustion.

When a hydrocarbon such as propane is used as a combustible substance, in a thermal atmosphere associated with its combustion,
4N ₂ O + C ₃ H ₈ + 3O ₂ → 4N ₂ + 4H ₂ O + 3C
A chemical reaction of O ₂ is established, and N ₂ O is thermally decomposed.

Further, according to the present invention, a conduit, a first supply part for supplying N ₂ O from one end of the conduit into the conduit, and an intermediate part of the conduit, which is provided with a combustible material in the conduit. A second supply part for supplying a volatile substance, and a combustion part provided at the other end of the conduit for combusting the combustible substance to generate a thermal atmosphere for decomposing N ₂ O. hydrocarbons flammable substances, hydrogen, alcohol, ether, aldehyde, ketone, ester, carboxylic acid, fats, phenols, ammonia, at least one is applicable are selected from amine and aniline, N ₂ O thermal decomposition apparatus Will be provided.

According to this apparatus, N ₂ O can be surely thermally decomposed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, an N ₂ O thermal decomposition apparatus 1 has a conduit 2, which comprises a horizontal pipe section 3 and a vertical pipe section 4 rising from one end thereof. A first supply unit 5 for supplying N ₂ O into the conduit 2 is provided on one end side of the horizontal pipe unit 3. The first supply unit 5 is made of N ₂ O or N
_It consists of a tank 6 filled with a gas containing ₂ O and a blower 7. The blower 7 has a suction port 8 connected to the tank 6 via a suction pipe 9 and a discharge port 10 connected to the horizontal pipe section 3. . A second supply unit 11 that supplies a combustible substance into the conduit 2 is provided at a connecting portion between the horizontal pipe portion 3 and the vertical portion 4. The second supply unit 11 has a tank 12 filled with a combustible substance, which is a combustible gas in the embodiment, and a supply pipe 13 extending from the tank 12, and the outlet side of the supply pipe 13 is the conduit 2 Is disposed in the lower end portion of the vertical pipe portion 4 penetrating the peripheral wall thereof and the outlet is directed upward. A safety valve 14 that closes when backfire occurs in the supply pipe 13 is provided.

As shown in FIGS. 2 to 4, the other end of the conduit 2 is provided with a combustion section 15 for producing a thermal atmosphere in which combustible gas is burned to decompose N ₂ O. The combustion section 15 is configured as follows.

The combustion section 15 is provided with a backfire prevention device 16 located on the inlet side, that is, the lower side, and a combustion cylinder 17 provided on the upper surface side in an upright state. The backfire prevention device 16 has an outer cylindrical body 18 and a short column body 19 fitted therein. The outer cylindrical body 18 has a cylindrical portion 21 having a plurality of cooling fins 20 on the outer peripheral surface thereof, and flange portions 22 and 23 existing at both ends thereof. The flange portion 24 existing at the upper end of the vertical pipe portion 4 is attached to the one flange portion 22 by a plurality of bolts 25. Annular step portions 26 and 27 are formed at both open ends of the outer tubular body 18, and holding members 28 and 29 for holding the short column body 19 are fixed to the annular step portions 26 and 27, respectively. Each of the holding members 28 and 29 has the same shape, and has a radial shape that is connected to the annular mounting portion 30 fitted to the annular stepped portions 26 and 27 and that is connected to the inner peripheral surface of the annular mounting portion 30 and contacts the end surface of the short columnar body 19. The holding portion 31 serves as a gas distribution window 33 between the adjacent constituent portions 32 of the radial holding portion 31. The short column body 19 has a plurality of small diameter holes 34 for gas flow extending in the axial direction, and both openings of each small diameter hole 34 face each window 33 of the radial holding portion 31. In this way, the backfire preventer 16 is connected to the other end of the conduit 2, and each small diameter hole 34 communicates with the inside of the conduit 2. Since the gas flow rate is limited by each small diameter hole 34, the region near the backfire prevention device 21 in the vertical pipe portion 4 mixes N ₂ O and a combustible gas to form a mixed region A.
_Acts as ₁ .

The combustion cylinder 17 is composed of a cover cylinder 36 and a heating cylinder 37 arranged inside the cover cylinder 36. A flange portion 38 at one end of the cover cylinder 36 has a backfire prevention device 16.
It is attached to the flange portion 23 of the shaft 2 by a plurality of bolts 39. The heating cylinder 37 includes an inner cylinder portion 40, an intermediate cylinder portion 41, and an outer cylinder portion 42 which are concentrically arranged. These inner cylinders 4
0, the intermediate tubular portion 41 and the outer tubular portion 42 are formed of wire mesh, and their lower ends are welded to the upper radial holding portion 31. A baffle plate 43 that disperses the flame is welded to the upper end of the inner tubular portion 40. A gas burner 44 for igniting the mixed gas and an igniter 45 for igniting the gas of the gas burner 44 are arranged near the flange portion 38 of the cover cylinder 36.

First and second feeds 5, 5 in conduit 2
A discharger 46 is arranged between the two 11, and the discharger 46 is N ₂
An arc discharge region in which O flows is formed. As clearly shown in FIGS. 5 and 6, in the discharger 46, the cylindrical outer electrode 4
7 having the same shape on both annular end faces of 7
The second end plates 48 and 49 are respectively applied and attached to the outer electrode 47 by a plurality of bolts 50. The outer electrode 47 has a large-diameter hole portion 51 existing on the first end plate 48 side,
Small-diameter hole portion 52 existing on the second end plate 49 side, both hole portions 51,
52 and a tapered hole portion 53 that connects the two
The inner peripheral surfaces of 2, 53 are mirror-finished.

The inner electrode 5 is provided between the first and second end plates 48 and 49.
4 is retained. The inner electrode 54 includes a disk-shaped portion 55 located in the middle, first and second frustoconical portions 56 and 57 having large diameter ends connected to both ends thereof, and a first frustoconical portion 5.
6 of the small diameter end face of 6 and a smaller diameter than that
The shaft portion 58, the short cylindrical portion 59 protruding from the small-diameter end surface of the second truncated cone portion 57 and having the same diameter as the short circular cylindrical portion 5
9 and a second shaft portion 60 having a smaller diameter than that of the second shaft portion 60. Those components 55, 56, 57, 5
8, 59, 60 are coaxial and their axes coincide with those of the outer electrode 47. The first shaft portion 58 has a through hole 6 coaxial with the outer electrode 47 formed on the first end plate 48.
1 and the small-diameter end surface of the first truncated cone 56 is the first
It contacts the end plate 48. In the outer electrode 47, the first truncated cone portion 56 and the disk-shaped portion 55 are located in the large diameter hole portion 51, and the second truncated cone portion 57 is in the large diameter hole portion 51, the tapered hole portion 53 and the small diameter hole portion. The short cylindrical portion 59 is located inside the small-diameter hole portion 52. Second shaft portion 6
0 is fitted in the through hole 62 formed coaxially with the outer electrode 47 formed in the second end plate 49, and the end face of the short cylindrical portion 59 contacts the second end plate 49. The disk-shaped portion 55, the first and second frusto-conical portions 56 and 57, and the short cylindrical portion 59 are mirror-finished, and arc discharge is generated between the disk-shaped portion 55 and the large-diameter hole portion 51. A cylindrical gap d necessary for this is formed.

In the first and second end plates 48 and 49, a plurality of small holes 63 and 64 are formed at equal intervals around the through holes 61 and 62 (see FIG. 6), and each small hole 63 and 64 is an outer electrode. 47
Communicate with inside.

On the outer surface side of the first end plate 48,
The end plate 48 has a flange portion 66 at one end of the inlet tube 65.
Is attached by a plurality of bolts 67, and its inlet tube 65
The inside communicates with each small hole 63 of the first end plate 48. Further, on the outer surface side of the second end plate 49, a flange portion 69 existing at one end of the outlet tube 68 is provided on the second end plate 49 with a plurality of bolts 70.
The outlet cylinder 68 communicates with the small holes 64 of the second end plate 49.

On the outer peripheral portion of the outer electrode 47, one connecting terminal 71 is screwed to the bus bar at bisected positions, the other connecting terminal 72 is rod-shaped, and the first end plate 4 is formed.
8 is inserted into an elongated hole 73 formed so as to pass between the adjacent small holes 63 from its outer peripheral portion and is screwed to the first shaft portion 58. Both lead wires 74 and 75 extending from both connection terminals 71 and 72 are connected to an AC power supply device 76. In the figure, 77 is a seal ring.

The outer electrode 47 is made of stainless steel such as JI.
The inner electrode 54 is made of Al alloy, for example, JIS 5052. The first and second end plates 48, 49 are made of synthetic resin, for example, bakelite with cloth, and the flange portions 66, 6
The inlet and outlet tubes 65 and 68 having 9 are made of Al alloy, for example J
It is composed of IS 5052.

The flammable substance includes at least one selected from hydrocarbons, hydrogen, alcohols, ethers, aldehydes, ketones, esters, carboxylic acids, fats and oils, phenols, ammonia, amines and anilines. Among substances, those that are liquid and solid are gasified and used as flammable gas.

Aliphatic hydrocarbons include straight-chain alkanes such as methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, eicosane, henicosan, triacontane, 3- Methylhexane, 3-ethyl-4,7
-Alkanes having side chains such as dimethylnonane, cycloalkanes such as cyclopropane, cyclobutane, cyclopentane, and cyclohexane, and side chains such as cis-1,2-dimethylcyclopropane, trans-1,2-dimethylcyclopropane Linear alkenes such as cycloalkane, ethylene, propylene, isobutylene, isoprene and piperylene, alkenes having side chains such as 2-ethyl-1-pentene and 1,5-dimethylcyclopentene, alkynes such as acetylene and 6-methyl-3. -Applicable are alkynes having side chains such as octyne. For example, typical substances of alkane include natural gas, liquefied petroleum gas, straight-run gasoline, kerosene, light oil, lubricating oil (wax) and the like.

Suitable aromatic hydrocarbons include benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, styrene, cumene, naphthalene, anthracene and phenanthrene.

Alcohols include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 1-pentanol, 1-hexanol, ethylene glycol and glycerin, and 1-butanol-2-methyl-1-. Those having a side chain such as propanol are applicable.

Examples of ethers include dimethyl ether, ethyl methyl ether, diethyl ether and the like. Formaldehyde, acetaldehyde, propionaldehyde, etc. correspond to aldehydes. Acetone, ethyl methyl ketone, etc. correspond to the ketone.

Esters include methyl formate, ethyl formate,
Examples include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, pentyl acetate, octyl acetate, ethyl butyrate, pentyl butyrate, and the like.

The chain carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, lauric acid, palmitic acid, stearic acid and other monovalent saturated carboxylic acids, acrylic acid, oleic acid, linoleic acid, linolenic acid and the like. And monovalent unsaturated carboxylic acids such as oxalic acid, succinic acid and adipic acid, and divalent unsaturated carboxylic acids such as maleic acid (cis form) and fumaric acid (trans form). Examples of aromatic carboxylic acids include benzoic acid, phthalic acid, terephthalic acid, salicylic acid and the like.

Oils and fats include myristic acid, palmitic acid,
Saturated fatty acids such as stearic acid and unsaturated fatty acids such as oleic acid, linoleic acid and linolenic acid are applicable.

Phenols include phenol, o-cresol, m-cresol, p-cresol, hydroquinone, salicylic acid, 1-naphthol, 2-naphthol and the like. The amine includes primary amine, secondary amine,
Examples include tertiary amines and quaternary ammonium salts.

The thermal decomposition of N ₂ O will be described below.

A test gas containing N ₂ O and O ₂ is prepared, and a tank 6 filled with the test gas is provided in the first supply section 5. Further, propane is selected as the combustible gas, and the tank 12 filled with the propane is provided in the second supply unit 11.

When the safety valve 14 of the second supply unit 11 is "open", propane is flown into the conduit 2 through the supply pipe 13, and the ignition gas burner 44 of the combustion unit 15 is ignited so that propane is generated in the combustion cylinder 17. To burn.

The inner and outer electrodes 47, 5 are controlled by the AC power supply 76.
A discharge voltage is applied to 4 and the blower 7 is operated to allow the test gas to flow into the conduit 2. In the state where the test gas is flowing through the discharger 46, arc discharge is generated between the disc-shaped portion 55 of the inner electrode 54 and the inner peripheral portion of the large-diameter hole portion 51 of the outer electrode 47 surrounding the inner electrode 54. An arc discharge is generated at the generating portion, and the arc discharge spreads around the second truncated cone portion 57 and the short cylindrical portion 59 along the flow of the test gas, and the spread area is the arc discharge area A ₂ . Become. N ₂ O in the test gas is activated into a radical state while flowing through this arc discharge region.

The test gas is the backfire prevention device 16
Mixed area A in the vicinity₁Mixed gas with propane at
Is prepared, and the mixed gas is used as a backfire prevention device 16
Through each of the small diameter holes 34, and flows into the combustion cylinder 17. Mixed
Propane in the combined gas is ignited by the gas burner 44
Combustion, N under the thermal atmosphere accompanying the combustion₂O is thermally decomposed
To be done. The combustion temperature of propane is 1040 ℃, the combustion flame
It ’s blue, but it ’s N ₂When O is mixed, the combustion temperature is 11
High temperature that rises to 70 ° C and the combustion flame changes to orange
The environment appears. In this case, N₂Thermal decomposition of O is 4N₂
O + C₃H₈+ 3O₂→ 4N₂+ 4H₂O + 3CO₂When
It is represented by the chemical reaction formula. The color of the heating cylinder 37
When the propane turns red due to the heat of combustion of propane, its heating
For ignition, propane can be ignited by the heat of the cylinder 37.
Extinguish the gas burner 44.

As a specific example, the test conditions are as follows: Test gas composition: 15 vol% N ₂ O, 21 vol% O ₂ and 6
4 vol% N ₂ ; gas flow rate by blower 7: 25 L / mi
n; N ₂ O and the volume ratio of the propane (C ₃ H _8): 1: 1; the discharge voltage of the outer electrode 47,54 and discharge current: 7 kV, 30 mA; set to N ₂ O thermal decomposition The results shown in Table 1 were obtained.

[0034]

[Table 1]

From Table 1, it was revealed that N ₂ O was completely pyrolyzed.

Table 2 shows the results of the second and third tests, and these tests were conducted by changing the N ₂ O concentration and the propane concentration in the test gas.

[0037]

[Table 2]

As is clear from Table 2, it was found that N ₂ O was completely pyrolyzed.

The thermal decomposition of N ₂ O is possible without using the discharge vessel 46. In this case, it is necessary to make the concentration of combustible substances such as propane higher than that when the discharger 46 is used because of the increase in heat quantity. For example, the volume ratio of N ₂ O and propane is 1: 9. Set to.

When hydrogen is used as the combustible substance
N₂Thermal decomposition of O is₂O + 3H ₂+ O₂→ N₂+3
H₂It is performed based on a chemical reaction formula such as O.

[0041]

According to the present invention, the thermal decomposition method of N ₂ O and the thermal decomposition method for carrying out the method, which makes it possible to completely decompose N ₂ O by adopting relatively simple means. A device can be provided.

[Brief description of drawings]

FIG. 1 is a front view showing an example of an N ₂ O thermal decomposition apparatus.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 of FIG.

4 is a sectional view taken along line 4-4 of FIG.

5 is a sectional view taken along line 5-5 of FIG.

6 is a sectional view taken along line 6-6 of FIG.

[Explanation of symbols]

1 ...... Pyrolysis device 2 ...... Conduit 5 ………… First supply unit 11 ………… Second supply unit 15 ………… Combustion unit 16 ………… Backfire prevention device 34 …… … Small diameter hole 46 ………… Discharger A ₁ ……… Mixing area A ₂ ……… Arc discharge area

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 25, 2002 (2002.6.2)
5)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

The inner and outer electrodes 47, 5 are controlled by the AC power supply 76.
A discharge voltage is applied to 4 and the blower 7 is operated to allow the test gas to flow into the conduit 2. In a state where the test gas is flowing through the discharger 46, a cylindrical shape between the disk-shaped portion 55 of the inner electrode 54 and the inner peripheral portion of the large-diameter hole portion 51 of the outer electrode 47 surrounding the inner electrode 54. The gap d becomes the arc discharge generation region B, and the arc discharge is generated.
Click is spread to the second frustoconical portion 57 and a short cylindrical portion 59 around along the flow of the test gas, the spreading zone arc wave
The 及 area A _2. N ₂ O in the test gas is activated and becomes a radical state while flowing through the arc discharge generation region B and the arc spread region A ₂ .

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

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Claims (7)

[Claims] 1. At least one flammable substance selected from hydrocarbons, hydrogen, alcohols, ethers, aldehydes, ketones, esters, carboxylic acids, oils and fats, phenols, ammonia, amines and anilines is burned and burned. N ₂ O thermal decomposition method, which comprises decomposing the N ₂ O under a thermal atmosphere with. 2. The method for thermally decomposing N ₂ O according to claim 1, wherein N ₂ O and the flammable substance are mixed and the flammable substance is ignited. Wherein N in ₂ O, subjected to a pretreatment which it is passed through a arc discharge atmosphere, according to claim 1 or 2 N ₂
O thermal decomposition method. 4. A conduit (2), a first supply part (5) for supplying N ₂ O from one end of the conduit (2) into the conduit (2), and an intermediate part of the conduit (2). And a second supply part (1) for supplying a combustible substance into the conduit (2).
1) and a combustor (15) which is provided at the other end of the conduit (2) and burns the combustible substance to develop a thermal atmosphere for decomposing N ₂ O. At least one selected from hydrocarbons, hydrogen, alcohols, ethers, aldehydes, ketones, esters, carboxylic acids, fats and oils, phenols, ammonia, amines and anilines corresponds to the volatile substance of N ₂ O. Pyrolysis device. 5. A discharger (46) is arranged between the first and second supply parts (5, 11) of the conduit ( ₂ ) to form an arc discharge area (A ₂ ) through which N ₂ O flows. The thermal decomposition apparatus for N ₂ O according to claim 4, which is used. 6. The N ₂ O thermal decomposition apparatus according to claim 4, wherein the combustion section (15) has a backfire preventer (16) on the inlet side thereof. 7. The backfire preventer (16) has a plurality of small diameter holes (34) for gas flow, which are connected to the other end of the conduit (2) and communicate with the inside of the conduit (2). 7. The thermal decomposition of N ₂ O according to claim 6, wherein a region near the backfire preventer (16) in the conduit (2) functions as a mixed region (A ₁ ) of N ₂ O and the combustible substance. apparatus.