JP2008271994A - Decomposition treatment method of organic compound and its apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a decomposition treatment method of an organic compound for improving decomposition efficiency when decomposing an organic matter or the like containing halogen and improving the durability of a reaction pipe itself, and its apparatus. <P>SOLUTION: In the method and apparatus of decomposing the organic compound inside the reaction pipe 41 in the atmosphere of superheated steam, the decomposition treatment method of the organic compound and its apparatus are used as the basic means, wherein a nickel-based alloy containing nickel and iron for a fixed amount is used as a material of the reaction pipe 41, the iron is made to act as a reaction assisting material and separated from the material inside the reaction pipe by decomposition and corrosion reaction, and thus the surface area of nickel as a catalyst is enlarged inside the reaction pipe 41 to execute decomposition treatment. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and apparatus for decomposing organic compounds that are hardly decomposable substances such as environmental pollutants, and in particular, as a reaction tube for reacting an organic compound such as chlorofluorocarbon gas in an atmosphere of superheated steam, a certain amount of nickel and iron are used. By using a reaction tube made of the nickel-base alloy contained, iron in the alloy constituting the reaction tube is used as a reaction aid in the initial decomposition step, and as the iron falls off from the alloy, the reaction tube By expanding the surface area of nickel having a catalytic action inside, it is possible to maintain and improve the decomposition efficiency and improve the durability of the reaction tube.

  It has been pointed out that organic compounds such as chlorofluorocarbons that have been used as refrigerants and sprays and halon gas that has been used as fire extinguishing agents have been pointed out as environmental pollutants. Various measures have been proposed as a global concern. For example, hydrothermal reaction methods, incineration methods, explosion reaction decomposition methods, microbial decomposition methods, ultrasonic decomposition methods, plasma reaction methods, and the like have been proposed for chlorofluorocarbon gas treatment methods.

  Among these treatment methods, the hydrothermal reaction method is not limited to chlorofluorocarbons, etc., but is versatile for all degradable substances mainly composed of organic solvents such as trichlene, waste oil, dioxin, PCB, manure, etc. It is attracting attention as a processing method. In this hydrothermal reaction method, for example, Freon gas can be decomposed into safe substances such as sodium chloride and carbon dioxide.

Regarding equipment for realizing the hydrothermal reaction method, processing experiments using an autoclave in the laboratory, for example, the mixing ratio of caustic soda solution, ethanol, chlorofluorocarbon solution, temperature setting value, pressure setting value and reaction time setting Although experiments on the values have been conducted, the hydrothermal reaction is usually carried out at 300 to 450 ° C. while maintaining the high temperature and high pressure conditions of 100 to 350 kg / cm ² .

  The present applicant previously proposed a method and apparatus for treating environmental pollutants by hydrothermal reaction treatment according to Patent Document 1. The contents will be briefly described based on the flow of the chlorofluorocarbon treatment system shown in FIG. 11. A tank 1 contains a mixed solution of chlorofluorocarbon, caustic soda, and ethanol, which is heated from a pipe 4 through a pump 2 and a flow meter 3. It is sent to the exchanger 5, reacted in the hydrothermal reactor 6, then sent again to the cooler 7 through the heat exchanger 5, and sent from the cooler 7 to the separator 9 via the pressure regulating valve 8 for flow rate control. Then, the water is separated into clean water and clean materials by the separator 9. The tank 1a, the pump 2a, and the flow meter 3a shown in the figure are systems used in such a case because they may be gasified at room temperature depending on the type of the fluorocarbon gas.

  The pumps 2 and 2a are ordinary slurry pumps. As this slurry pump, suction is vacuum, the pumping force is high, and the volumetric efficiency is required, and a high-concentration slurry pump cylinder such as a high-concentration slurry, a powder mixed slurry, an acid, or an alkaline slurry can be used.

  As shown in FIG. 12, the hydrothermal reactor 6 meanders so that the mixed solution passing through the heat exchanger 5 is discharged from the outlet 11 through the pipe 12 around which the band heater 13 is wound. Configured. A necessary number of the band heaters 13 are arranged at appropriate intervals in the longitudinal direction of the pipe 12 and are controlled so that the temperature in the pipe 12 becomes constant. Further, the cooler 7 employs a normal cooling device in which a cooling water passage is formed around the reaction tube.

  However, since the hydrothermal reactor 6 must maintain high-temperature and high-pressure conditions, the structure of the pressure regulating valve 8 becomes complicated and expensive, and further, mechanical strength such as tensile stress is required for use at high temperature and high pressure. It is difficult to design to withstand thermal stress, and the materials used are limited. In addition, the mechanism for pumping and discharging the solid-liquid mixture under high temperature and high pressure is complicated, and it is necessary to change the structure depending on the type of substance to be decomposed, which makes it difficult to control the operation. Along with this, there is a possibility that the piping 4 may be damaged during operation, which leaves a difficulty from the viewpoint of ensuring safety.

  In response to the above, according to Patent Document 2, the present applicant made it possible to decompose the organic compound under normal pressure, thereby constituting the apparatus without causing damage to the piping or the discharge valve due to high temperature and pressure. A decomposition method and apparatus capable of arbitrarily selecting the material were proposed. That is, the fluorocarbon charged in the decomposition target tank and the water charged in the water tank are sent to the heater through the pipe, and the internal heater and the external heater arranged in advance in the heater are operated to make the inside of the heater 500 Superheated steam is generated by heating to 750C to 750C. Since the temperature of the superheated steam necessary for the decomposition treatment varies depending on the object to be decomposed, it is set according to the object to be decomposed. For example, in the case of chlorofluorocarbon gas, the superheated steam is 500 ° C. to 750 ° C. and polyethylene is about 400 ° C.

An iron piece that is a substance that generates hydrogen by reacting with superheated steam is arranged in the heater. When this iron piece is heated to approximately the same temperature, the superheated steam comes into contact with the iron piece and Produces magnetite and hydrogen.
3Fe + 4H ₂ O → Fe ₃ O ₄ + 4H ₂ (1)

  The hydrogen produced here has a very strong reducing power and combines with many substances to decompose organic compounds. The reactor is also heated in advance so as to maintain the temperature of the superheated steam by driving the internal heater and the external heater, and the reaction of the above formula (1) is performed by the presence of the iron piece arranged in the reactor. Since superheated steam is also present in the reactor in the same atmosphere, hydrolysis also takes place concurrently, and a complex decomposition reaction proceeds. Along with this, the decomposition rate of the object to be decomposed is increased and the decomposition rate is improved.

  It is appropriate to heat the inside of the reactor to approximately the same temperature as in the heater, and a predetermined reaction time elapses while the superheated steam passes through the reactor, and the organic compounds in the superheated steam are decomposed. Then, the gas of the decomposition product sent into the cooler at the next stage and decomposed is cooled and liquefied.

  The drainage liquid is introduced from the cooler into the gas-liquid separator, the liquid material flows into the neutralization device, is discharged after a predetermined neutralization treatment, and is stored in the drainage tank. Alternatively, only water as a solvent is continuously supplied to the reactor as superheated steam by a heater, and an organic compound is supplied into the reactor in the atmosphere of the superheated steam of the solvent to allow a predetermined reaction time to elapse. it can. This configuration is suitable for the case of decomposing a solid organic compound other than fluid or gas, for example, PE, plastic, rubber, etc., as an object to be decomposed. While supplying to a reactor, transfer means, such as a feeder, are provided in the reactor.

  Further, according to Patent Document 3, the applicant of the present invention uses a normal pressure in a system for decomposing chlorofluorocarbons, which are environmental pollutants, polyethylene, plastics, organic compounds having benzene nuclei, and other difficult-to-decompose substances such as industrial waste. Decomposition treatment of organic compounds that does not cause damage to pipes or discharge valves due to high temperature and high pressure by allowing decomposition in the state of water, and even when water is used as a solvent, the decomposition rate is increased and the reaction does not change over time In addition, for the purpose of providing the apparatus, water is used as a solvent, and either or both of the heater and the reactor are configured using iron or an iron-containing alloy, Decompose organic compounds by direct reaction, reduction reaction by hydrogen generated by direct reaction of iron and superheated steam, and hydrolysis reaction by superheated steam Proposed a cracking process and apparatus of organic compounds so as to sense.

According to such a method, by supplying only water as a solvent and performing a predetermined reaction in the reactor, direct reaction between iron and an organic compound, reduction with hydrogen generated by direct reaction between iron and superheated steam. It is possible to decompose organic compounds by any form of reaction and hydrolysis reaction with superheated steam, and it is not necessary to maintain the inside of the reactor at high temperature and high pressure unlike the decomposition means utilizing hydrothermal reaction. Therefore, there is an advantage that a reactor and other pressure regulating valves are not required and operational control is easy.
Japanese Patent No. 2612249 Japanese Patent No. 3219706 Japanese Patent No. 3607624

  In the reactor according to Patent Document 3 described above, a method of putting a heat source from the outside or inside is used. However, when the temperature of the inner wall of the reactor is low, a sufficient reaction cannot be expected. It is composed of an efficient metal material, and the corrosion rate of the reactor itself becomes a problem when decomposing organic substances containing halogen. For example, when chlorofluorocarbon cracking is performed using austenitic stainless steel such as SUS304, SUS310S, etc. as the material of the reactor and the reaction tube, the thickness of the corrosion is reduced after several hundred hours on the outlet side where the decomposition reaction occurs in the tube having a thickness of 4 mm Leakage occurs, and local corrosion such as pitting corrosion occurs on the condensing side, making it unusable in about one month. In particular, halides generated by decomposition increase the corrosive action of metals in combination with oxygen and steam at high temperatures, so the life of the reactor becomes extremely short.

  Furthermore, a means using ceramics such as SiC as a reactor or a coating means thereof may be considered, but the corrosion resistance is high, but the fundamental difficulty is that the decomposition reaction of the organic compound is difficult to occur because it is not a metal. Arise. Further, although there is a liquid combustion apparatus for halogen gas decomposition, since it is highly corrosive, it is necessary to apply anticorrosion means with refractory bricks on the inner surface. Although this refractory brick has good corrosion resistance, there is a problem that the base material corrodes due to the occurrence of cracks or gas entering the joint gaps. Further, there is a method of using titanium as a constituent material on the downstream side, but the problem remains that corrosion is remarkable.

Corrosion of metals with a high-temperature halogen gas has a high vapor pressure and a high volatility of the halide, which is a corrosion product, so that the corrosion reaction is fast and the metal is consumed rapidly.
Fe + Cl ₂ → FeCl ₂
2FeCl ₂ → FeCl ₃ (low boiling point)
Cr + Cl ₂ → CrCl ₃
2 / 3Cr + Cl ₂ → 2 / 3CrCl ₃ (sublimation)
Ni + Cl ₂ → NiCl ₂

Reaction with HCl gas be the same, the corrosion behavior is similar to Cl _2.
Fe + 2HCl → FeCl ₂ + H ₂
Cr + 2HCl → CrCl ₂ + H ₂
Ni + 2HCl → NiCl ₂ + H ₂

In addition, when oxygen is present, a halide is generated via an oxide, and an oxychlorination reaction that promotes corrosion occurs. In the case of iron, the following reaction occurs due to chlorine as a halogen.
Fe + 2HCl → FeCl ₂ + H ₂
2FeCl ₂ + 2 / 3O ₂ → Fe ₂ O ₃ + 2Cl ₂
Fe ₂ O ₃ + 6HCl → 2FeCl ₃ + 3H ₂ O

Since the saturation vapor pressure of FeCl ₃ is high and the melting point (308 ° C.) and the boiling point (315 ° C.) are both low, the progress of corrosion becomes remarkable. Chromium also has a high saturated vapor pressure of CrCl ₃ and CrCl _2. Similarly, CrCl ₃ causes a sublimation reaction, and the corrosion rate is also high. On the other hand, nickel has a melting point and boiling point of NiCl ₂ and NiCl ₃ of 900 ° C. or higher, and it has been found that the halogen corrosion reaction is not as remarkable as that of other metals.

  On the other hand, it is known that fluorine gas as a halogen gas behaves similarly to chlorine gas. However, although there are high-temperature corrosion data for each single halogen gas, it is a study up to about 500-600 ° C, and it is an exothermic reaction due to the decomposition reaction as described above, and chlorofluorocarbon gas and its decomposition gas at 800-1000 ° C or higher. The fact is that there is almost no data in Japan.

  In addition, the reactor has been devised such as cooling the reactor from the outside or mixing a gas that does not contribute to the reaction inside to increase the heat capacity to suppress the temperature rise and slow the corrosion rate of the reactor. However, the corrosion rate cannot be greatly delayed, and the reactor is replaced once every several months. Since iron, carbon, and the like contained in the metal material act as a reaction aid and a catalyst during the reaction, the reaction can be performed at a temperature lower than the conventional reaction temperature. However, the reaction itself as a reaction aid is an exothermic reaction, and since the reaction itself is further promoted, a vigorous reaction is continued. However, although there are advantages that an improvement in decomposition efficiency and an increase in throughput can be expected. As a result, the corrosion rate of the reactor is not improved, and the reactor must be replaced in the same period as described above.

  Direct heating has also been attempted to avoid these drawbacks, but as a means of doing so, heat treatment tiles etc. are attached inside the reactor to burn the auxiliary fuel and maintain the reactor temperature high. However, it is necessary to continue the reaction. For this reason, propane, methane, petroleum, and an oxygen source, which are fuels that are not originally required for the reaction, are required, and a large amount of by-products are generated in the reaction process, so that the residence time and the like must be strictly controlled. In addition, the tile in the reactor is damaged, and there is a disadvantage that a renewal is required once every six months or once a year and a long stoppage is required.

  From the viewpoint of maintenance, it is advantageous to use a material having high corrosion resistance and a long life. Although there is an idea that the normal stainless steel is used in a short-term replacement, the replacement frequency is every two to three weeks in a 24-hour operation. The problem of blockage also occurs.

  As described above, the contribution of nickel to hydrocarbon adsorption, activation, hydrogen adsorption, and halide desorption in the cracking reaction with hydrocarbons is remarkable from the viewpoint of its catalytic action. It is inferred that the base alloy has resistance to corrosion at high temperatures.

  Accordingly, in view of the above-described conventional problems, the present invention aims to improve the decomposition efficiency at the time of decomposition of an organic substance or the like containing halogen and to improve the durability of the reaction tube itself, and an apparatus therefor Is intended to provide.

  In order to achieve the above object, the present invention uses a nickel-base alloy containing a certain amount of nickel and iron as a reaction tube material for decomposing an organic compound in a reaction tube in an atmosphere of superheated steam. In the initial step, decomposition and corrosion reactions cause the iron to act as a reaction aid from the material inside the reaction tube and leave it to leave nickel, thereby expanding the surface area of nickel inside the reaction tube and performing a decomposition treatment. The organic compound decomposition treatment method and apparatus as described above are used as basic means.

  As described above, iron is removed to make the inside of the reaction tube a nickel-based surface, thereby delaying the progress of corrosion of the reaction tube, improving durability, and reacting with iron released by nickel catalysis. Complement the effect as an auxiliary material to improve the decomposition efficiency.

  A nickel-based alloy having a nickel content of 40 wt% to 80 wt% and an iron content of 2 wt% to 40 wt% is used. Nickel-based alloys include alloys of nickel 40 wt% to 50 wt%, chromium 20 wt% to 25 wt%, iron 25 wt% to 40 wt%, molybdenum 0 wt% to 5 wt%, or nickel 50 wt% to 65 wt% % Alloy, 20% to 25% by weight of chromium, 2% to 10% by weight of iron, 10% to 15% by weight of molybdenum, or 60% to 80% by weight of nickel, 10% to 25% by weight of chromium One or more alloys selected from alloys of 2 wt% to 10 wt% of iron and 0 wt% to 10 wt% of molybdenum are used. Moreover, the temperature of superheated steam shall be 700 to 1200 degreeC, and especially the temperature of superheated steam when an organic compound is CFC shall be 650 to 1100 degreeC.

  According to the organic compound decomposition treatment method and apparatus according to the present invention, when an organic compound such as chlorofluorocarbon gas is subjected to a predetermined decomposition reaction in a reaction tube in an atmosphere of superheated steam, nickel and iron are used as materials for the reaction tube. By using a certain amount of nickel-base alloy, direct reaction between iron and organic compounds contained in the nickel-base alloy, reduction reaction by hydrogen generated by direct reaction between iron and superheated steam, and hydrolysis reaction by superheated steam The organic compound can be decomposed by any of these forms. In particular, in the present invention, the surface area of nickel as a catalyst in the reaction tube is reduced by a decomposition and corrosion reaction in which iron acts as a reaction aid and is released from the nickel-base alloy constituting the reaction tube in the initial stage of the decomposition reaction. Since the decomposition process can be expanded, the decomposition efficiency can be maintained and improved at a high level and the durability of the reaction tube itself can be improved. Both the decomposition efficiency and the durability are in conflict. Can be improved at the same time.

  The gas component after the decomposition can be liquefied and discharged by cooling. Since the main process is heating under normal pressure, a high-pressure pump is unnecessary, and there is no concern that the discharge valve or the piping will be damaged. Furthermore, since all the reactions are closed systems that occur in the reaction tube, there is an effect that there is no secondary contamination.

  Furthermore, according to the present invention, since the process proceeds at a low pressure, the reaction tube may be made of a nickel-based alloy containing a certain amount of nickel and iron that can withstand a predetermined high temperature, and mechanical strength and tensile stress or thermal stress. There is an advantage that a design for enduring is not particularly required, and it is easy to take measures against breakage of various devices, and it is easy to automate the device itself, and there is an effect that safety is high.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an organic compound decomposition treatment method and apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram schematically showing one embodiment of an organic compound decomposition treatment apparatus according to the present invention, in which 21 is a tank to be decomposed such as chlorofluorocarbon, 22 is a pump to be decomposed, and 23 is a solvent. As a water tank, 24 is a water pump, and 25 is a heater. An internal heater 26 and an external heater 27 are arranged in the heater 25. A pump capable of pumping the material to be decomposed according to the material to be decomposed is selected as the material to be decomposed pump 22, and a slurry pump having high volumetric efficiency and high pumping force capable of pumping high concentration slurry, powder mixed slurry and the like. It is appropriate to use

  Reference numeral 29 denotes a reactor, which is an apparatus for performing a decomposition process by reacting a material to be decomposed with superheated steam and hydrogen of a solvent for a predetermined time while maintaining a predetermined temperature in a reaction tube 41 provided therein. The reactor 29 is provided with internal heaters 30 and 30 and external heaters 31 and 31 for heating the reaction tube 41 provided inside.

  The inside of the reactor 29 is not pressurized and is at a normal pressure with the discharge port side opened. In other words, the pressure of the piping on the inlet side is a pressure gradient with only pressure loss due to the pipeline. Or you may make it attract | suck with a blower etc. from the discharge port side. As described above, it is one of the features of the present invention that the reactor 29 can decompose the material to be decomposed using an open type apparatus that does not force the pressurization unlike the conventional high pressure hydrothermal reaction apparatus. is there. Further, a slight pressure is naturally generated in the reactor 29 due to the superheated steam, and the decomposition target is transferred by the pressure gradient. The normal pressure indicates that the outlet is opened without forcibly pressurizing to a high pressure as in the conventional hydrothermal reactor.

  FIG. 2 is a schematic view showing the internal structure of the reactor 29, FIG. 3 is a cross-sectional view of the state along the line AA in FIG. 2 opened up and down, and 41 in the figure is a tubular reaction tube, 42 is an upper case disposed at a position covering the periphery of the reaction tube 41, 43 is a lower case, 30 is an internal heater disposed in the vicinity of the reaction tube 41, 44 is a heat insulating material for the internal heater, 45, 46 Is a heat insulating material covering the open ends of the upper case 42 and the lower case 43. Connected to the reaction tube 41 are an air / oxygen introduction tube 47 and an introduction tube 48 of a mixture of Freon gas and water. In this way, when water as a solvent and Freon gas as a substance to be decomposed are mixed and supplied to the reactor 29 in advance, one introduction pipe is sufficient. On the other hand, when supplying the fluorocarbon gas which is a substance to be decomposed and water as a solvent to the reactor 29 individually, a steam introduction pipe 49 is provided, and the steam obtained by heating water from the steam introduction pipe 49 is supplied to the reactor 29. The reaction tube 41 is supplied, and only the Freon gas is supplied from the introduction tube 48 of the mixture of the Freon gas and water. As shown in FIG. 3, the upper case 42 and the lower case 43 are configured to be opened and closed by a hinge 50. In FIG. 2, the external heater is not shown.

  In this embodiment, the reaction tube 41 has a diameter of 50 to 250 mm, a length of 1000 to 3000 mm, a thickness of 2 to 20 mm in the decomposition part, and the composition of the gas used for the decomposition is CFC gas: 10 to 30 vol. %, Air: 0-50%, steam: 10-50%, gas flow rate: 25 m / sec.

  The provision of a plurality of reactors 29 according to the type of substance to be decomposed is also included in the embodiment of the present invention. For example, when a solid is to be decomposed, if it is put in the reactor 29, latent heat of vaporization is required, and the temperature is lowered and a stable reaction field cannot be formed. Therefore, it is appropriate to install a plurality of reactors 29, first perform appropriate primary treatment such as gasification in the first reactor 29, and then perform decomposition according to the original purpose in the next reactor 29. In addition, the heater 25 can equip separately the heater which heats the water as a solvent, and the heater which heats the chlorofluorocarbon as a to-be-decomposed substance. It is important that the reaction tube 41 is heated to a red hot temperature like the heater 25. A predetermined reaction time elapses while the superheated steam passes through the reaction tube 41, and the organic compound in the superheated steam is decomposed and fed into the cooler 32 in the next stage.

  Reference numeral 32 denotes a cooler, and a pipe 33 communicating with the pipe led out from the reactor 29 is disposed in the cooler 32. 34 is an inlet for cooling water, and 35 is an outlet for cooling water. 36 is a gas-liquid separator, and 37 is a neutralization device. The other end of the pipe 38 led out from the cooler 32 is inserted in the vicinity of the bottom of the gas-liquid separator 36 and led out from the gas-liquid separator 36. The other end of the pipe 39 is inserted into the neutralization device 37. Reference numeral 40 denotes a processing liquid discharge port.

  In order to solve the problems of the reaction tube 41 and improve both decomposition efficiency and durability at the same time, the present inventors have made various materials with different composition ratios from the metal material constituting the reaction tube 41. As a result of carrying out a reaction test on, and intensively researching and examining the amount of by-products during the reaction, durability, decomposition efficiency, etc., the material shows high decomposition efficiency, few by-products, and long life of the reaction tube itself The following knowledge was obtained regarding the composition, the blending ratio, and the catalytic action for the reaction.

  First, the present inventors indirectly heated a reaction tube using SUS304, SUS310S or various nickel-based alloys as stainless steel conventionally used as a reaction tube material to 650 ° C. to 1200 ° C. Reactions in which corrosive substances are produced, especially decomposition reactions such as chlorofluorocarbon, halon, and PCB, and reactions in which highly corrosive acidic gases such as HF and HCl are produced from the reaction of substances containing halogen I did it. As a result, it was found that in the decomposition reaction process, iron and chromium are preferentially halogenated from the alloy material constituting the reaction tube and fall out of the alloy bond due to corrosion. For this reason, the corrosion product which is a part of the metal that has fallen off remains on the surface of the alloy, but the alloy surface has a fine structure mainly composed of nickel from which iron and chromium have fallen off due to secondary surface treatment by decomposition and corrosion reaction. It was found that the surface was deposited with a large number of honeycomb-like small holes.

  Furthermore, if the nickel content in the alloy exceeds a certain amount, the acid gas composed of these halogens has strong corrosion resistance, and after this state, the subsequent corrosion rate becomes extremely slow. I didn't make any progress, and I knew that I would maintain this state for a long time. That is, there is a correlation between the nickel contained in the reaction tube and the lifetime of the reaction tube. Also, nickel has a strong catalytic action on carbon hydrogen compounds, and the presence of nickel with an increased surface area makes the decomposition efficiency the reaction using iron as a reaction aid and the reaction using iron as a catalyst as described in the prior art. And there is almost no difference from the decomposition efficiency obtained by these synthesis reactions. This is because iron and chromium on the metal surface are corroded and fall off, leaving only nickel that is not corroded, and the portion where iron and chromium are present forms a honeycomb-like small hole. This brings about the effect of increasing the contact area, resulting in an increase in the catalytic efficiency of nickel.

  FIG. 4 is a schematic view showing a state in which Cr chloride and Fe chloride 52 have fallen off from the Ni—Cr—Fe alloy 51 constituting the reaction tube 41 and the Ni-based layer 53 remains, and iron on the metal surface. As a result of chromium being corroded and falling off, only the nickel-based layer 53 that is not corroded by the Ni—Cr—Fe alloy 51 remains, and the portion where iron and chromium are present forms a honeycomb-like small hole. This honeycomb-shaped small hole has the effect of increasing the contact area with the reaction gas, resulting in an increase in the catalytic efficiency of nickel.

  Therefore, in the present invention, a nickel-base alloy containing a certain amount of nickel and iron is used as a material for the reaction tube 41, and iron is used as a reaction aid from the material inside the reaction tube in the initial stage of the decomposition reaction. It is a basic feature that a reaction tube 41 that performs decomposition treatment by expanding the surface area of nickel as a catalyst inside the reaction tube by secondary surface processing by decomposition and corrosion reaction by separating is used. Yes. As the nickel-base alloy used as the material of the reaction tube 41, a nickel-base alloy having a nickel content of about 40 wt% to 80 wt% and an iron content of about 2 wt% to 40 wt% is used. This is because if nickel is not more than 40% by weight, sufficient corrosion resistance and catalytic action due to nickel cannot be obtained, and sufficient corrosion resistance and catalytic action are obtained, and considering the balance with other alloy components, it is up to about 80% by weight. It is desirable to do. Furthermore, if the iron content is not 2% by weight or more, the action of iron as a reaction aid cannot be obtained and the decomposition efficiency is poor. It will be lacking. Specifically, nickel-base alloys A, B, and C having the following configurations are suitable.

[Nickel base alloy A]
As a nickel base alloy according to the present invention, an alloy of 40 wt% to 50 wt% nickel, 20 wt% to 25 wt% chromium, 25 wt% to 40 wt% iron, 0 wt% to 5 wt% molybdenum (hereinafter referred to as nickel) Base alloy A). In the present embodiment, the specific structure of the nickel-based alloy A is an alloy of 42.1% by weight of nickel, 21.5% by weight of chromium, 29.6% by weight of iron, and 2.9% by weight of molybdenum (hereinafter referred to as nickel-based alloy a). )It was used.

[Nickel base alloy B]
As a nickel base alloy according to the present invention, an alloy of 50 wt% to 65 wt% of nickel, 20 wt% to 25 wt% of chromium, 2 wt% to 10 wt% of iron, and 10 wt% to 15 wt% of molybdenum (hereinafter referred to as nickel) Base alloy B). In the present embodiment, the specific structure of the nickel base alloy B is an alloy of 58.2 wt% nickel, 22.2 wt% chromium, 4.0 wt% iron, and 13.5 wt% molybdenum (hereinafter referred to as nickel base alloy b). )It was used.

[Nickel base alloy C]
As the nickel-based alloy according to the present invention, an alloy of nickel 60 wt% to 80 wt%, chromium 10 wt% to 25 wt%, iron 2 wt% to 10 wt%, molybdenum 0 wt% to 10 wt% (hereinafter referred to as nickel) Base alloy C). In this embodiment, an alloy (hereinafter referred to as nickel-base alloy c) of 75.8 wt% nickel, 15.5 wt% chromium, and 7.6 wt% iron was used as a specific configuration of the nickel-base alloy C. Alternatively, a plurality of alloys selected from these nickel-base alloys A, B, and C can be used. Table 1 shows the chemical compositions of the nickel-base alloys A, B, and C, and Table 2 shows the chemical compositions of the nickel-base alloys a, b, and c and conventional materials SUS304 and SUS310S.

  In the present invention, as described above, a nickel-base alloy containing a certain amount of nickel and iron is used as a material for the reaction tube 41, and iron is used as a reaction aid in the material inside the reaction tube 41 in the initial stage of the decomposition reaction. Surface area having many fine honeycomb-shaped small holes mainly composed of nickel from which iron and chromium have fallen off in the reaction tube 41 by secondary surface processing by decomposition and corrosion reaction by separating from the alloy bond by acting Expands. In addition, the heater 25 can employ the same structure as that of the reaction tube 41 using a nickel-based alloy containing a certain amount of nickel and iron.

  The operation mode of this embodiment will be described by taking as an example the case of decomposing an organic compound such as chlorofluorocarbon, which is an environmental pollutant. First, chlorofluorocarbon is introduced into the decomposition target tank 21 and the decomposition target pump 22 and the water pump 24 are activated, so that chlorofluorocarbon and water as a solvent are fed into the heater 25 through the pipe and mixed at an appropriate ratio. The

  Superheated steam is generated by heating the heater 25 in a red-hot state by operating the internal heater 26 and the external heater 27 previously disposed in the heater 25. Since the temperature of the superheated steam necessary for the decomposition treatment varies depending on the type of the organic compound, it is set according to each decomposition target object. For example, in the case of Freon gas, it is appropriate to use superheated steam at around 650 ° C. to 1100 ° C., but the heating temperature above may be used. In particular, the decomposition rate of the object to be decomposed can be increased by setting the temperature of the nickel-based alloy containing a certain amount of nickel and iron constituting the heater 25 to a red-hot temperature.

  At the initial stage of the use of the reaction tube 41, almost no catalytic reaction of nickel can be expected. The reason is that nickel is strongly bonded as an alloy and the exposed surface of the nickel is small. However, at this time, iron, which is an alloy component, acts as a reaction aid or catalyst, and the reaction efficiency is maintained high. Iron and chromium on the surface gradually fall off as iron halides and chromium halides, and as described above, honeycomb-shaped small holes are formed on the metal surface, and the catalytic action of nickel gradually increases. . In this way, the action of iron and nickel complement each other's action time, and the decomposition efficiency can be kept high.

  That is, a predetermined reaction time elapses while an organic compound such as chlorofluorocarbon gas passes through the reaction tube 41 in the superheated steam atmosphere, and the decomposed gas is sent to the cooler 32 in the next stage. In the cooler 32, the cooling water is supplied from the inlet 34 of the cooling water and flows out from the outlet 35, whereby the gas of the decomposition product decomposed in the pipe 33 communicating with the reaction tube 41 is cooled and liquefied. The temperature in the cooler 32 may be a temperature at which the decomposition product gas can be liquefied. By liquefying in this way, generation of by-products is prevented.

  The drained liquid enters the gas-liquid separator 36 through the pipe 38, the harmless gas generated by the gas-liquid separation is dissipated into the atmosphere, and the liquid material flows into the neutralizing device 37, where the predetermined amount of A sum process is performed and the liquid is discharged from the discharge port 40 and stored in a drainage tank (not shown). It is also possible to incorporate a heat exchanger into the cooler 32, recover the heat cooled by the heat exchanger, and reuse the recovered heat for generating superheated steam.

  In the above description, only water as a solvent is superheated by the heater 25 and then continuously supplied to the reaction tube 41 of the reactor 29, and the reaction tube 41 of the reactor 29 in the atmosphere of the superheated vapor of the solvent is supplied. It is also possible to feed the material to be decomposed to a predetermined reaction time. This configuration is suitable for the case of decomposing a solid decomposable material other than fluid or gas, such as PE, plastic, rubber, etc., as the decomposable material. 29, and a means for transferring a material to be decomposed such as a feeder may be provided in the reaction tube 41.

  A temperature range of 650 ° C. to 1200 ° C. can be adopted as the reaction temperature in the reaction tube 41. The reaction temperature of 650 ° C. is used when the amount of the organic compound is small, or when the reaction rate does not matter, and has the advantage that the corrosion of the reaction tube 41 is minimized. The reaction temperature of 1200 ° C. is used in the case where the amount of organic compound is large and the reaction rate is increased. However, since the corrosion deterioration of the reaction tube 41 can be accelerated, it is required to select the optimum temperature according to the substance to be decomposed. The

  Therefore, using R-12, R-22, and R-134A as chlorofluorocarbon gas, chlorofluorocarbon: 10-30 vol%, air: 0-50%, steam: 10-50%, gas flow rate: 2-5 m / sec Decomposition was performed.

When the Freon gas is R-12, CF ₂ Cl ₂ + H ₂ O → 2CO ₂ + 2HF + 2HCl + H ₂ (2)
In the case of R-22, CHClF ₂ + 2H ₂ O → 2CO ₂ + HCl + HF + H ₂ (3)
For _{R-134A C 2 H 2 F} 4 + 2H 2 O → 2CO 2 + 4HF + H 2 ..................... (4)
It becomes.

  Equations (2), (3), and (4) are exothermic reactions, and the wall temperature of the reaction tube 41 becomes higher as the reaction proceeds, and about 900 to 950 is downstream of the reaction tube 41 where the decomposition reaction is completely completed. Rise to ℃. In any decomposition reaction, the decomposition rate of Freon is 99.99%.

  Table 3 shows the material of the reaction tube 41 when decomposing R-12 as chlorofluorocarbon gas, and the year after 1000 hours when using the conventional SUS304 and SUS310S and the nickel-based alloys a, b, and c according to the present invention. The amount of corrosion thinning (mm) converted to (8760 hours) is shown. As for the corrosion thinning amount, the initial wall thickness of each tube was measured in advance, and the corrosion thinning amount was obtained from the outer surface of the tube by measuring the wall thickness by UT (ultrasonic wave) after the end of each test. FIG. 5 is a graph showing the relationship between the nickel amount (% by weight) of the reaction tube 41 and the annual corrosion thinning amount shown in Table 3 when decomposing R-12 as chlorofluorocarbon gas.

  As shown in Table 3, when R-12 is disassembled, the conventionally used SUS304 corrodes 136.7 mm per year, whereas the nickel base alloy b only has 14.0 mm, and the nickel base alloy c The corrosion resistance is only 7.9 mm, and the corrosion resistance is about 10 times and about 17 times that of SUS304. While SUS310S corrodes 87.6 mm, nickel-base alloy b only corrodes 14.0 mm, and the difference is 6 times or more. The corrosion thinning amount with respect to R-12 increases in the order of nickel base alloy c <nickel base alloy b <nickel base alloy a <SUS310S <SUS304. Then, as shown in FIG. 5, it can be seen that the average corrosion rate decreases exponentially as the amount of Ni in the nickel-base alloy increases.

  Table 4 shows the results after 1000 hours and annually (8760) when the conventional SUS304 and SUS310S and the nickel-base alloys a, b, c according to the present invention are used as the material of the reaction tube 41 when decomposing R-22 as chlorofluorocarbon gas. Corrosion thinning amount (mm) converted to time) is shown. As for the corrosion thinning amount, the initial wall thickness of each tube was measured in advance, and the corrosion thinning amount was obtained from the outer surface of the tube by measuring the wall thickness by UT (ultrasonic wave) after the end of each test. FIG. 6 is a graph showing the relationship between the nickel content (% by weight) of the reaction tube 41 and the annual corrosion thinning amount shown in Table 4 when R-22 is decomposed as chlorofluorocarbon gas.

  Table 5 shows the results after 1000 hours and annually (8760) when the conventional SUS304 and SUS310S and the nickel-base alloys a, b, c according to the present invention are used as the material of the reaction tube 41 when decomposing R-134A as chlorofluorocarbon gas. Corrosion thinning amount (mm) converted to time) is shown. As for the corrosion thinning amount, the initial wall thickness of each tube was measured in advance, and the corrosion thinning amount was obtained from the outer surface of the tube by measuring the wall thickness by UT (ultrasonic wave) after the end of each test. FIG. 7 is a graph showing the relationship between the nickel amount (wt%) of the reaction tube 41 and the annual corrosion thinning amount shown in Table 5 when R-134A is decomposed as chlorofluorocarbon gas.

  As shown in Tables 4 and 5, even when R-22 or R-134A is decomposed, nickel-based alloys a, b, and c containing 40% by weight or more of nickel have a nickel content. It has a corrosion resistance of about 2.5 times to about 17.5 times that of 20.3% by weight of SUS310S and 8.3% by weight of SUS304. The amount of corrosion thinning for R-22 and R-134A increases in the order of nickel base alloy c <nickel base alloy b <nickel base alloy a <SUS310S <SUS304. As shown in FIGS. 6 and 7, it can be seen that the average corrosion rate decreases exponentially as the amount of Ni in the nickel-based alloy increases.

  Therefore, if the nickel content in the nickel-based alloy exceeds 40% by weight, the reaction tube 41 has a temperature of 650 ° C. to 1100 ° C. for decomposing CFCs such as R-12, R-22, and R-134A. Corrosion resistance can be significantly improved. In addition, the amount of corrosion thinning tends to be slightly higher in the order of R-134A <R-22 <R-12. From these results, it can be considered that the composition of the cracked gas depends on the composition of HCl and HF.

  Table 6 standardizes the decomposition reaction time when the general structural rolled steel (SS) is used as the material of the reaction tube 41 as 1, and the conventional SUS304 and SUS310S and the nickel-based alloys a, b, c according to the present invention. FIG. 8 is a graph showing the relationship between the reaction time ratio shown in Table 6 and the corrosion thinning amount. The decomposition reaction time ratio was determined by measuring the time required for the R-12 decomposition rate to reach 99.99% when processing using a small reactor with a processing temperature of 1 kg / h at a decomposition temperature of 850 ° C. Calculated.

  Table 7 is the same data as Table 6 when R-22 is decomposed instead of R-12, and FIG. 9 is a graph showing the relationship between the reaction time ratio and the corrosion thinning amount shown in Table 7. is there. The decomposition reaction time ratio was determined by measuring the time required to achieve a decomposition rate of R-22 of 99.99% when processing using a small reactor with a processing temperature of 1 kg / h at a decomposition temperature of 850 ° C. Calculated.

  Table 8 is the same data as Table 6 when R-134A is decomposed instead of R-12, and FIG. 10 is a graph showing the relationship between the reaction time ratio and the corrosion thinning amount shown in Table 8. is there. The decomposition reaction time ratio was determined by measuring the time required for the R-134A decomposition rate to reach 99.99% when processed using a small reactor with a decomposition temperature of 850 ° C. and a throughput of 1 kg / h. Calculated.

  As shown in Tables 6 to 8 and FIGS. 8 to 10, it can be seen that the amount of corrosion thinning (corrosion rate) and the decomposition reaction time ratio are in an inversely proportional relationship. Therefore, the lower the decomposition reaction time ratio, the higher the corrosion rate of the metal. This is because the decomposition reaction time ratio is governed by iron, and with the short reaction time ratio, iron is consumed by the iron halide and the corrosion rate is increased.

  As a result of analyzing the surface after the decomposition reaction in SUS310S, oxides and chlorides containing iron as a main component are deposited in the scale that has been corroded due to corrosion, while Fe-Cr is present in the metal matrix. It was confirmed that the Fe and Cr components were removed from the metal structure in the -Ni alloy. Although Ni remains, it is somewhat reduced. It was confirmed that the main component of the nickel base alloy c remained on the surface of the base material even after the decomposition reaction.

  Therefore, conventional materials such as SUS304 and SUS310S have a small decomposition reaction time ratio, and the decomposition reaction is performed quickly, but at the same time, the amount of corrosion thinning is large, the rate of corrosion is fast, the life of the reaction tube is short, and cumbersome replacement. Is required. On the other hand, in the nickel base alloys a, b and c according to the present invention, the decomposition reaction time ratio is larger than that of the conventional example, but it is in a practical range, and the progress of corrosion is slow and sufficient. Corrosion resistance and durability. Thus, the nickel-base alloys a, b, and c according to the present invention can satisfy both the corrosion resistance and the decomposition reaction time in a well-balanced manner. When the reaction tube 41 is made of nickel as the raw material, the same decomposition reaction time ratio is 50.78. Similarly, 51.88 for copper, 52.38 for SiC, and 56.17 for alumina. Since the material does not contain iron, the decomposition reaction takes too much time and is not suitable as a material for the reaction tube. Therefore, in the present invention, a nickel base alloy having a nickel content of 40 wt% to 80 wt% and an iron content of 2 wt% to 40 wt% is used.

  As shown in FIG. 4, iron and chromium are corroded from the surface of the alloy of the reaction tube 41, so that only the nickel-based layer 53 that is not corroded by the Ni—Cr—Fe alloy 51 remains, and the presence of iron and chromium. This part forms a small honeycomb hole. This small hole brings about the effect of increasing the contact area with the reaction gas, resulting in an increase in the catalytic efficiency of nickel. As the Ni content in the Ni-Cr-Fe alloy increases, the reaction time ratio increases, but the corrosion rate of the metal decreases. This is a result of significant suppression of Ni consumption by decomposed halides. Therefore, in the case of a metal material, if the Ni content is low, the decomposition reaction time ratio decreases, but the corrosion rate increases. Therefore, if the decomposition reaction time ratio exceeds a certain level, a material having a high Ni content is required. It is preferable to use it. In the embodiment of the present invention, the decomposition rate in the decomposition test by gas treatment is 99.99%, and therefore, when the decomposition reaction time ratio is 30 or less, there is no problem even if a Ni alloy material is used. It was recognized that there was a great effect on the increase in the life of the reaction tube 41.

  As described above in detail, according to the present invention, iron in the material is used as a reaction aid in the initial stage of the decomposition reaction by using a nickel-based alloy containing a certain amount of nickel and iron as the material of the reactor. Since the decomposition treatment can be carried out by making it act and detach and increase the surface area of nickel as a catalyst, the decomposition efficiency can be improved and the durability of the reactor itself can be improved at the same time. Therefore, not only detoxification treatment of organic compounds that are environmental pollutants such as chlorofluorocarbons used as refrigerants and sprays and halon gas used as fire extinguishing agents, but also various organic solvents, waste oil, dioxin, PCB, manure, etc. The present invention can be effectively used as a versatile treatment method and apparatus for all substances to be decomposed, which are hardly decomposed substances mainly composed of industrial waste.

1 is a system diagram showing a basic embodiment of the present invention. The schematic diagram which shows the internal structure of the reactor to which this invention is applied. Sectional drawing of the state which opened the part in alignment with the AA of FIG. 2 up and down. The schematic diagram which shows the nickel base alloy material used by this invention. The graph which shows the relationship between the nickel amount of a reaction tube at the time of decomposition | disassembly of Freon gas R-12, and the amount of corrosion thinning. The graph which shows the relationship between the nickel amount of a reaction tube at the time of decomposition | disassembly of Freon gas R-22, and the amount of corrosion thinning. The graph which shows the relationship between the nickel amount of a reaction tube at the time of decomposition | disassembly of Freon gas R-134A, and the amount of corrosion thinning. The graph which shows the relationship between the reaction time ratio at the time of decomposition | disassembly of Freon gas R-12, and the amount of corrosion thinning. The graph which shows the relationship between the reaction time ratio at the time of decomposition | disassembly of Freon gas R-22, and the amount of corrosion thinning. The graph which shows the relationship between the reaction time ratio at the time of decomposition | disassembly of Freon gas R-134A, and the amount of corrosion thinning. The system figure which shows the outline | summary of the conventional freon processing method. The schematic diagram of the hydrothermal reaction apparatus in the system diagram of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 ... Decomposed substance tank 22 ... Decomposed substance pump 23 ... Water tank 24 ... Water pump 25 ... Heater 26, 30 ... Internal heater 27, 31 ... External heater 29 ... Reactor 32 ... Cooler 36 ... Gas-liquid separator 37 ... Neutralizer 41 ... Reaction tube 42 ... Upper case 43 ... Lower case 50 ... Hinge 51 ... Ni-Cr-Fe alloy 52 ... Cr chloride and Fe chloride 53 ... Ni-based layer

Claims (15)

In a method of decomposing an organic compound in a reaction tube in an atmosphere of superheated steam,
A nickel-base alloy containing a certain amount of nickel and iron is used as a material for the reaction tube, and iron is removed from the material inside the reaction tube by a decomposition and corrosion reaction, and nickel remains as a catalyst. A decomposition treatment method for an organic compound, wherein the decomposition treatment is performed. In a method of decomposing an organic compound in a reaction tube in an atmosphere of superheated steam,
A nickel-base alloy containing a certain amount of nickel and iron is used as a reaction tube material, and the reaction tube interior is separated by causing iron to act as a reaction aid from the inside of the reaction tube by decomposition and corrosion reactions. A method for decomposing an organic compound, wherein the decomposing process is performed by expanding the surface area of nickel as a catalyst.   The organic compound decomposition treatment method according to claim 1 or 2, wherein the decomposition treatment is performed by complementing the action of the separated iron as a reaction aid by the catalytic action of nickel.   4. The method for decomposing an organic compound according to claim 1, wherein iron is removed to make the inside of the reaction tube a nickel-based surface, thereby delaying the progress of corrosion of the reaction tube and improving durability.   By making the inside of the reaction tube a nickel-based surface by detaching iron, the progress of corrosion of the reaction tube is delayed to improve durability, and as a reaction aid for the separated iron by the catalytic action of nickel The organic compound decomposition treatment method according to claim 1, wherein the decomposition efficiency is improved by complementing the action of   6. The decomposition of an organic compound according to claim 1, 2, 3, 4 or 5, wherein a nickel-based alloy having a nickel content of 40% to 80% by weight and an iron content of 2% to 40% by weight is used. Processing method. As a nickel base alloy, an alloy of nickel 40 wt% to 50 wt%, chromium 20 wt% to 25 wt%, iron 25 wt% to 40 wt%, molybdenum 0 wt% to 5 wt%,
Or an alloy of nickel 50 wt% to 65 wt%, chromium 20 wt% to 25 wt%, iron 2 wt% to 10 wt%, molybdenum 10 wt% to 15 wt%,
Alternatively, one or more alloys selected from alloys of nickel 60 wt% to 80 wt%, chromium 10 wt% to 25 wt%, iron 2 wt% to 10 wt%, and molybdenum 0 wt% to 10 wt% are used. A method for decomposing an organic compound according to claim 1, 2, 3, 4, 5, or 6.   The method for decomposing organic compounds according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the temperature of the superheated steam is 700 ° C to 1200 ° C.   The method for decomposing an organic compound according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the temperature of the superheated steam when the organic compound is chlorofluorocarbon is 650 ° C to 1100 ° C. In a reaction tube for decomposing organic compounds in an atmosphere of superheated steam,
An organic compound decomposition treatment apparatus characterized in that a nickel-based alloy having a nickel content of 40 wt% to 80 wt% and an iron content of 2 wt% to 40 wt% is used as a material for the reaction tube. . In a reaction tube for decomposing organic compounds in an atmosphere of superheated steam,
A nickel base alloy having a nickel content of 40 wt% to 80 wt% and an iron content of 2 wt% to 40 wt% is used as a material for the reaction tube. An organic compound decomposition treatment apparatus characterized in that iron is allowed to act as a reaction aid from a raw material to be separated and nickel remains as a catalyst. In a reaction tube for decomposing organic compounds in an atmosphere of superheated steam,
A nickel base alloy having a nickel content of 40 wt% to 80 wt% and an iron content of 2 wt% to 40 wt% is used as a material for the reaction tube. An apparatus for decomposing an organic compound, wherein the surface area of nickel in a reaction tube is increased by causing iron to act as a reaction aid and to be separated from the material.   13. The organic compound decomposition treatment apparatus according to claim 10, 11 or 12, wherein iron is removed to make the inside of the reaction tube a nickel-based surface, thereby delaying the progress of corrosion of the reaction tube and improving durability.   By removing the iron and making the inside of the reaction tube a nickel-based surface, the progress of corrosion of the reaction tube is delayed to improve durability, and the action of iron released by the catalytic action of nickel as a reaction aid The organic compound decomposition treatment apparatus according to claim 10, wherein the decomposition efficiency is improved by complementing the above. As a nickel base alloy, an alloy of nickel 40 wt% to 50 wt%, chromium 20 wt% to 25 wt%, iron 25 wt% to 40 wt%, molybdenum 0 wt% to 5 wt%,
Or an alloy of nickel 50 wt% to 65 wt%, chromium 20 wt% to 25 wt%, iron 2 wt% to 10 wt%, molybdenum 10 wt% to 15 wt%,
Alternatively, one or more alloys selected from alloys of nickel 60 wt% to 80 wt%, chromium 10 wt% to 25 wt%, iron 2 wt% to 10 wt%, and molybdenum 0 wt% to 10 wt% are used. The organic compound decomposition treatment apparatus according to claim 10, 11, 12, 13, or 14.

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