KR101092866B1 - High Efficient Plasma Reactor for Thermal Destruction Processes of High Concentrated Perfluorocompounds Gases - Google Patents

Abstract

The present invention relates to a high efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine gas, and more particularly, highly concentrated fluorine gas pyrolysis made of an optimal material and design structure to easily pyrolyze the highly concentrated fluorine-containing gas during a plasma treatment process. It relates to a high efficiency thermal plasma reactor for.
To this end, the present invention is the internal reaction tube and the external reaction tube to form a predetermined interval for the reactor flow path between each other overlapping double tube reactor; It is arranged to form a waste gas flow passage at regular intervals in the outer diameter portion of the external reaction tube, a reactor gas supply port and waste gas supply port for supplying the reactor and waste gas to the reactor flow passage and waste gas flow passage, respectively A first external cooling tube formed at a lower end thereof; A second external cooling tube arranged to form a cooling water flow passage at a predetermined interval in an outer diameter portion of the first external cooling tube, and having a cooling water supply port and a cooling water discharge port communicating with the cooling water flow passage at upper and lower ends, respectively; A discharge block coupled to lower ends of the inner and outer reaction tubes and coupled to a lower flange formed integrally with lower ends of the first outer cooling tube and the second outer cooling tube; It provides a high efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that configured to include.

Description

High Efficient Plasma Reactor for Thermal Destruction Processes of High Concentrated Perfluorocompounds Gases}

The present invention relates to a high efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine gas, and more particularly, highly concentrated fluorine gas pyrolysis made of an optimal material and design structure to easily pyrolyze the highly concentrated fluorine-containing gas during a plasma treatment process. It relates to a high efficiency thermal plasma reactor for.

CO ₂ , CH _4, etc. remaining in the atmosphere forms an atmospheric layer that absorbs infrared rays supplied from the sun and returns heat emitted from the earth to the earth's surface, so it is known as a global warming influence material, that is, a greenhouse gas.

In addition, fluorine-containing compounds such as hydrofluorocarbon (HFC), perfluorinated compound (PFC), and SF ₆ are also classified as greenhouse gases as long-lasting substances that do not decompose well in the atmosphere.

Although there are many fluorine-containing compounds that have the characteristics of greenhouse gases, HFC-based CHF ₃ , PFC-based CF ₄ , C ₂ F ₆ , C ₃ F ₈ , NF ₃ , which are used globally and have high global warming influence. _Six fluorine-containing gases, including SF ₆ and SF ₆ , were selected as the primary substances to be regulated for consumption and air emissions. Korea is expected to be classified as a greenhouse gas reduction country from 2014. There is an urgent need to secure countermeasures and reduction technologies.

The primary reduction target fluorine-containing gas to be a thermally and chemically stable, and is low toxic, corrosive, flammable easy to use, but by when released into the atmosphere reach not well decomposed to stratospheric greenhouse gas surrounding the earth, such as CO ₂ in air It absorbs infrared rays and increases the atmospheric temperature.

Extinguishing agents (CHF ₃ ), semiconductor process gases (CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , NF ₃ , SF ₆ ) and high-voltage equipment insulation gas (SF ₆ ) are also used in Korea. In order to reduce the amount of air emitted from the air, it is fundamentally to improve the process to reduce the use amount, to find alternative substances with low secondary environmental hazards, to replace the substances to be reduced, and to collect and safely dispose of the gas emitted from the process. Or a method of recycling after recycling, separation and purification after collection.

Although domestic industries continue to make efforts to reduce consumption through process improvement, the results are still insignificant. It is most desirable to find materials that have similar application characteristics to the substances to be reduced and have low secondary environmental hazards and replace them with all of them, but they are not only suitable for the manufacture of substitutes but also for applicability, human toxicity, and mass productivity. A relatively long study period is needed to verify.

The techniques known to date can be roughly classified into a burning method and a decomposition method using plasma as reliable methods for effectively decomposing fluorine-containing compounds such as PFCs, HFCs, and SF ₆ emitted. As a waste gas from a semiconductor manufacturing line or a collection refrigerant is difficult to define as a specific component and contains up to 200 mg / m 3 of nano-sized dust containing various gases, the system for treating fluorine-containing gas is very simple. This requires a system that is durable and simple to maintain.

Incineration, which is currently widely used as a fluorine-containing gas decomposition technology, is a combustion process in which flammable substances combine with oxygen to generate an exothermic reaction, and the amount of oxygen and the combustion state for the reaction temperature and residence time required for fluorine-containing gas decomposition must be adjusted.

In addition, the fluorine-containing gas decomposition products contain strong acid such as HF, which may cause corrosion of the rear end of the equipment due to the exhaust gas. Therefore, proper treatment is required. In addition, in addition to the treatment method by incineration of HFC-23, the following problems occur.

First, since the fluorine-containing compound is burned together with a large amount of hydrocarbon (natural gas / hydrogen) fuel at a temperature of 1000 ° C. or higher and quenched to 100 ° C. or lower, it has a low thermal efficiency resulting from this.

Second, air injection of about 10 times or more of the fluorine-containing gas to be removed is required, and post-treatment cost and device size generated by oxidizing HFC-23 are also increased, making it difficult to secure the site within the plant.

In other words, it is difficult to miniaturize the device by maintaining a long residence time for fluorine-containing gas decomposition. For example, when fluorine-containing gas decomposition is generally required, a residence time of 2 seconds at a temperature of 1200 ° C is increased. As the fuel and air supplied increase proportionally, longer reactors are needed, and the required area is increased along with the volume of the process.

Third, the decomposition efficiency decreases with time due to the fouling of the nozzle.

Fourth, the setting of the combustion temperature and the start time are necessary.

In order to alleviate or solve the problems of the incineration process, a process for suppressing secondary pollutants by using a high temperature generator such as plasma has been developed. The advantages of decomposing highly concentrated fluorine-containing gases by thermal plasma are as follows. Is the same as

1) When using the plasma process, since the residence time is only about 0.02 seconds, which is about 1/100 of the incineration process, the size and capacity of the absorption tower including the reactor can be greatly reduced. The process can be reduced in size by about 25% compared to the incineration process.

2) Considering the CO ₂ generated in the production of electricity used in the plasma process, about 40% of CO ₂ generation is suppressed compared to the incineration process.

 3) Secondary sources of pollution: Nitrogen oxides, dioxins, furans, etc. can be mainly used. However, the plasma process can be suppressed to within 10% of the incineration process by considering only the nitrogen oxides that can be calculated.

4) Safety: Plasma processes are much more advantageous from a safety point of view, since natural gas is always at risk of explosion when exposed to fire.

Of course, the above-mentioned plasma process is somewhat higher in operation and management costs compared to the incineration process, but this can be ignored because the operating cost required in the plasma process is less than 2% compared to the amount obtained in the CDM business.

In addition, it is considered to be very advantageous in terms of maintaining the operation of the process due to the eco-friendliness and the ease of use of the device, which greatly reduces secondary pollution.

In the case of plasma torch type gas injection part for large-capacity treatment, the non-feed type is mainly composed of anode and nozzle part of anode. In this case, anode is copper and anode is tungsten. However, the cavity type non-conveying DC plasma torch uses copper in both the anode and cathode materials.

Since the electrode material is very corrosive to oxidizing gas, in the present technology, an inert gas such as argon or nitrogen is mainly used for arc discharge, and the plasma torch composed of the electrode material is fluorine generated by thermal plasma. It supplies enough energy to pyrolysis the fluorine compound to the high temperature reactor that induces the gas decomposition reaction.

The plasma torch is composed of a magnetic coil that enables arc discharge to rotate at a calculated rate. The low-pressure arc discharge is similar to the glow discharge, so the electron temperature is very high compared to the ion temperature, but the atmospheric pressure As this rises, the electron temperature is close to the ion temperature and is almost the same at 100 torr or more.

Thus, the appearance of the arc becomes a bright core (core) and a small thin light around it, the temperature of the arc discharge itself is tens of thousands of K, the temperature of the three electron temperature, ion temperature and gas temperature are the same temperature, This is because there is a high chance of collision because of high air pressure, low electrode consumption and thermally homogeneous plasma.

In the current state of the art, fluorine compounds decomposed are mainly supplied from the back of the torch flame due to corrosion problems of the electrode, and the reaction zone is usually maintained at 1500-1800K.

On the other hand, the use of electrode materials, which are easily corroded in plasma processing systems, is an economical and technically significant obstacle in developing a large-capacity fluorine gas system using a plasma torch.

At the current level of technology, the process of decomposing by supplying fluorine gas to the bottom of the torch flame is selected. This method is not only disadvantageous in terms of energy efficiency, but also insoluble in the plasma torch environment during discharge. Since only gas is used, it is also very disadvantageous in terms of economics in developing a large-capacity plasma system.

Therefore, developing a highly corrosion-resistant electrode that can operate stably in an oxidizing environment can increase the flexibility of the process, such as supplying fluorine-containing gas to the upper end of the torch, resulting in a dramatic improvement in the plasma process in terms of economy and energy efficiency. have.

Likewise, it is important to develop a reactor in which fluorine-containing gas is decomposed. As a prerequisite, the analysis of the distribution of heat flow in a reactor that decomposes fluorine-containing gas is very important. Because it has a very important effect on.

Instead of enormous cost and time-consuming process for developing high efficiency decomposition system of fluorine-containing gas using arc thermal plasma, it is possible to computerize and analyze thermal plasma generation and ultra high temperature flow phenomenon inside reactor, It is possible to produce a wide range of forecast data and, in particular, to present the design and operating conditions of the optimal system for mass treatment of fluorine-containing gas based on the results of computational analysis to reduce trial and error that may occur in the construction and operation of the demonstration plant. This can improve the efficiency of development.

As described above, external emissions such as PFCs, HFCs, and SF ₆ generated during the refrigerant or semiconductor manufacturing process are very high, and in particular, many processes are connected to the CDM (Clean Development Mechanism) business because HFC-23 is emitted as a high-purity by-product. Although, small-scale fluorine-containing gases such as HFC134a and NF ₃ are discharged as diluent gas from the source.

Such fluorine-containing fluorine gas has a limited generation point compared to sporadically generated CO ₂ , which is relatively easy to reduce and the global warming index is relatively high. Therefore, if the treatment plant technology is secured, it is advantageous in terms of obtaining carbon emission rights.

In addition, applying a compact, safe and flexible thermal plasma process to apply small-scale treatment to relatively widely dispersed fluorine-containing gas sources can be said to be a more effective and useful means than incineration processes requiring large-scale facilities. .

Meanwhile, the thermal plasma reactor should be maintained at a temperature at which the fluorine-containing gas is decomposed well while being well mixed with the high-temperature plasma gas supplied from the plasma torch while being well supplied with the waste fluorine-containing gas and the reactive gas oxygen and water vapor. In addition, since the plasma ions must continuously collide with each other, the top of the reactor should have an optimal shape that minimizes the effects as well as a material resistant to erosion.

At this time, the water vapor of the reaction gas serves to supply hydrogen ions in the reactor, this hydrogen ion serves to inhibit the radicals from which the fluorine-containing gas is recombined again to generate harmful components.

If the oxidization reaction of fluorine-containing gas proceeds violently in the reactor, most of the gas is decomposed and strong acid is generated. Therefore, it is necessary to develop the design technology of thermal plasma reactor which is stable in oxidizing atmosphere. It is a very important means in determining the thermal plasma process.

The present invention has been studied in view of the above points, to provide an optimal material and shape of the fluorine-containing gas decomposition reactor which is the core in the process of decomposing fluorine-containing gas into thermal plasma, i) arc plasma Before decomposing by flame, vortex containing fluorine gas and reactant gas oxygen and water vapor should be well formed, and uniform contact with well mixed reaction gas and plasma flame should be ensured. Since the top of the reactor must continuously collide with the plasma ions, the top of the reactor must be of an erosion-resistant material as well as an optimal form to minimize the effects of the reactor. I) Oxidation reaction in the reactor during the decomposition of fluorine-containing gas As it proceeds vigorously, strong acids containing mostly fluorine are generated, It is necessary to select the material of the thermal plasma reactor, and in the long term, the erosion of the reactor due to plasma ion bombardment is inevitable, thus providing an optimal reactor shape design that minimizes replacement parts. The purpose is to provide a highly efficient thermal plasma reactor for high concentration fluorine gas pyrolysis that can be satisfied.

The present invention for achieving the above object is a double tube structure having a different diameter and height, the inner tube and the outer tube is a double tube reactor overlapping each other forming a predetermined interval for the flow path of the reactor body; It is arranged to form a waste gas flow passage at regular intervals in the outer diameter portion of the external reaction tube, a reactor gas supply port and waste gas supply port for supplying the reactor and waste gas to the reactor flow passage and waste gas flow passage, respectively A first external cooling tube formed at a lower end thereof; A second external cooling tube arranged to form a cooling water flow passage at a predetermined interval in an outer diameter portion of the first external cooling tube, and having a cooling water supply port and a cooling water discharge port communicating with the cooling water flow passage at upper and lower ends, respectively; A plate for connecting a plasma torch attached to an upper flange integrally formed at an upper end of the first external cooling tube and the second external cooling tube; A discharge block coupled to lower ends of the inner and outer reaction tubes and coupled to a lower flange formed integrally with lower ends of the first outer cooling tube and the second outer cooling tube; It provides a high efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that configured to include.

As a preferred embodiment of the present invention, the upper end of the inner reaction tube and the outer reaction tube is a free end, the same length is adopted, but a separate hollow on the upper end of the inner reaction tube to have a higher height than the outer reaction tube It is characterized in that the cap is detachably inserted.

In another preferred embodiment of the present invention, the inner reaction tube and the outer reaction tube, the plate for connecting the plasma torch is made of Inconel metal material, the first outer cooling tube and the second outer cooling tube, the discharge block is made of stainless steel 316 Characterized in that made of a material.

In another preferred embodiment of the present invention, the ratio of the distance (A) to the inlet of the inner reaction tube and the diameter (C) of the inner reaction tube from the position where the torch connection plate, which is the plasma torch outlet, is mounted (S = A) / C) is 0.5 to 1.75, and more preferably 1.125 characterized in that the production.

As another preferred embodiment of the present invention, the distance (B) from the position where the torch connection plate, which is the plasma torch outlet, is mounted to the tip of the external reaction tube in the range of 16 mm to 56 mm, more preferably set to 56 mm It is characterized by.

Particularly, the discharge block includes: a hollow discharge pipe that vertically coincides with the hollow portion of the internal reaction pipe; An upper flange and a lower flange formed integrally with the upper and lower ends of the discharge pipe; A boss portion protruding upward from a discharge pipe outer circumferential position on an upper surface of the upper flange; An auxiliary cooling pipe positioned between the upper flange and the lower flange and arranged at an outer diameter of the discharge pipe; .

In addition, the boss portion is inserted into the space between the lower end of the inner reaction tube and the outer reaction tube, the lower end of the outer reaction tube is supported on the upper surface of the upper flange and at the same time the lower end of the inner reaction tube is supported on the step do.

In addition, a sealing member is inserted between a bottom surface of a lower flange formed at lower ends of the first external cooling tube and the second external cooling tube and an upper surface of the upper flange of the discharge block, and a thermocouple is installed at a predetermined position of the discharge block. It is characterized by.

Through the above problem solving means, the present invention provides the following effects.

According to the present invention, by presenting a method for optimally designing and manufacturing a high-efficiency thermal plasma reactor for treating a large concentration of fluorine-containing gas, it is possible to reduce the process size of the existing incineration or plasma apparatus system by the amount of exhaust gas reduced, exhaust gas treatment Significant commercial and economic effects can be expected, as well as eliminating capacity expansion limitations and safety issues.

Therefore, fluorine-containing gas and oxygen, which are reactive gases, and water vapor form vortices to ensure uniform contact with the plasma flame, and internal and external reaction tubes of the reactor that must continuously collide with plasma ions such as Inconel. It can be applied to minimize the effects of erosion.

In addition, although erosion of the reactor due to plasma ion bombardment is inevitable, by providing a replaceable cap at the tip of the inner reaction tube, the influence of erosion can be further minimized, contributing to the overall cost reduction of the reactor and improvement of process stability. .

Figure 1a is a conceptual diagram for the computer simulation for the ultra-high temperature flow phenomenon occurring in the reactor zone for the production of the pyrolysis reactor of the present invention,
Figure 1b is a result of the temperature distribution computerized analysis in the reactor region of Figure 1a,
Figure 1c is a result of the axial velocity distribution computational analysis in the reactor region of Figure 1a,
2 is a cross-sectional view showing a high efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas according to the present invention;
3 is a reactor manufactured according to Example 1 of the present invention, the actual observation picture showing the appearance after the HFC-23 reaction experiment,
Figure 4 is a high-efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas according to the present invention, the main cross-sectional view illustrating the optimized plasma reactor shape,
Figure 5 is a reactor produced by adjusting the distance B from the plasma torch outlet to the external reaction tube according to Example 2 of the present invention, the actual observation picture showing the appearance after the HFC-23 reaction experiment.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention is to simulate the plasma torch area of the thermal plasma-based pyrolysis reactor using DCPTUN, MHD (Magnetohydrodynamics) computational analysis code, and pyrolysis reaction based on the characteristics of the thermal plasma jet calculated therefrom. The ultra high temperature flow phenomenon in the furnace area was simulated using a commercial FLUENT 6.2 code to produce an actual thermal plasma reactor. Ii) In the reactor area of a reactor having various shapes that actually pyrolyze HFC-23 fluorine-containing gas. The flow phenomenon was calculated from the calculated values, and the reactor shape was maximized by comparing the experimental value. I) The optimum reactor material was derived by measuring the corrosion resistance over a long period of time for various thermal plasma reactors. Based on the test results, the optimal plasma plasma material and the internal shape of the reactor are presented. The concentrated fluorinated gases intended to provide a highly efficient thermal plasma reactor for the highly concentrated fluorine-containing pyrolysis gas, characterized in such a point, the proposed effective reactor design method sikineunde decomposed by the thermal plasma process.

To this end, the computer simulation process for the optimal design of the thermal plasma reactor of the present invention was carried out, the accompanying Figure 1a for the design of the thermal plasma reactor according to the present invention, ultra-high temperature flow phenomenon in the reactor region of the reactor This is a conceptual diagram of computer simulations for.

As one of the torch operating conditions used in the actual pyrolysis process experiment, computer simulation was performed with current 50 A and nitrogen 50 slpm. The calculated arc voltage was 149.5 V, and the average voltage measured in the actual experiment was about 150.0 V. The thermal efficiency of the torch calculated is in good agreement with the thermal efficiency of the plasma torch using nitrogen discharge, commonly known as 0.677.

Computational analysis of the torch operating conditions indicated that a high-speed jet of up to 40 m / s at the outlet of the torch and the reactor inlet was ejected with a temperature distribution of about 4,000 K except for the flame region.

In addition, 49.02 slpm of air and 16.00 slpm of CHF ₃ were injected into the reactor at 300 K isothermal conditions, while 0.50 slpm of air and 20.80 slpm of water vapor were 400 K into the reactor. Computer simulations of the conditions injected into the conditions.

The geometrical dimensions of the reactor and the materials used were applied in the same way as the reactor of the reactor, and the exit boundary of the reactor was the position where the temperature was measured by the thermocouple. Was compared with the actual experimental results.

FIG. 1B is a graph showing the results of transcriptional simulation analysis of the temperature distribution in the reactor region of the reactor. Referring to this, it can be seen that the internal temperature of the reactor is more than 1,300K, indicating a sufficient temperature for thermal decomposition of CHF ₃ . Inconel's expected maximum temperature was lower than the melting point of about 1,500 K. In the channel into which steam is used as reactive gas, sufficient temperature of several hundred K is maintained so that water vapor can react effectively without condensation. The temperature predicted at the thermocouple measurement position was found to be in good agreement with the experimental results at about 1,600 K.

Figure 1c is a graph showing the axial velocity distribution in the reactor of the reactor, referring to this, the speed around the center axis of the reactor is approximately constant at about 20 m / s, the reaction time of about 0.02 seconds is expected It was found that vortices were formed due to the structure of the reactor and the high speed characteristics of the thermal plasma jet near the reactor wall about 30 mm away from the inlet of the reactor.

These vortices facilitate the mixing of thermal plasma jets with waste and reactor gases, making it possible to predict that most CHF ₃ will enter a high temperature zone sufficient for pyrolysis.

In this way, the computer simulation of the pyrolysis process in one operating condition and reactor structure was carried out by applying the conditions used in the actual pyrolysis process. It was confirmed that the simulation was done.

Therefore, based on the results of the computer simulation, it is possible to easily carry out the design of the thermal plasma reactor according to the present invention while extending the various operating and reactor conditions differently.

Here, the structure of the thermal plasma reactor according to the present invention will be described.

2 is a cross-sectional view showing a shape of a thermal plasma reactor according to the present invention, in which a double tube reactor 10 is arranged at a central portion, and a first external cooling is performed at an outer diameter of an external reaction tube 14 of the double tube reactor 10. The tube 16 is arrange | positioned, and the outer diameter part of the 1st external cooling tube 16 has the structure which the 2nd external cooling tube 20 was arranged.

The double tube reactor 10 is composed of an inner reaction tube 12 and an outer reaction tube 14 of siphon type having different diameters and heights made of Inconel metal, and the inner reaction tube 12 is external Longer than the reaction tube, the first external cooling tube 16 and the second external cooling tube 20 are adopted to be the same length but longer than the external reaction tube 14.

A reactor gas supply port 16a and a waste gas supply port 16b are formed at both ends of the lower end of the first external cooling tube 16, respectively, and a reactor gas supply port is provided at the lower end of the external reaction tube 16. A communication port 14a is formed to match the 16a, and a cooling water supply port 20a and a cooling water discharge port 20b are formed at lower and upper ends of the second external cooling pipe 20, respectively.

In addition, an upper flange 22 and a lower flange 24 are integrally assembled at upper and lower ends of the first outer cooling tube 16 and the second outer cooling tube 20, respectively, and a central portion of the upper flange 22 is formed. Attached to the plate 26 is a plasma torch connection plate made of an Inconel metal plate.

In addition, a discharge block 30 having a discharge pipe 32 made of SUS316 is assembled at the lower ends of the internal reaction tube 12 and the external reaction tube 14 of the double tube reactor 10.

Looking at the structure of the discharge block 30 in more detail, the hollow discharge pipe 32 and up and down coincident with the hollow portion of the inner reaction tube 12, and formed integrally with the upper and lower ends of the discharge pipe (32) The upper flange 34 and the lower flange 36, the boss portion 38 protruding upwardly at the outer peripheral position of the discharge pipe 32 on the upper surface of the upper flange 34, the upper flange 34 and the lower flange 36 It is configured to include an auxiliary cooling pipe (39) positioned between and arranged in the outer diameter portion of the discharge pipe (32).

In this case, the stepped portion 40 is formed at the boundary between the boss portion 38 and the discharge pipe 32, and the coolant inlet 39a and the coolant outlet 39b are formed at one side and the other side of the auxiliary cooling tube 39, respectively. do.

Therefore, the discharge block 30 is coupled to the lower end of the double tube reactor 10, the boss portion 38 to the space between the lower end of the inner reaction tube 12 and the outer reaction tube 14 of the double tube reactor (10). Is inserted and fastened, the lower end of the outer reaction tube 14 is supported on the upper surface of the upper flange 34, and the lower end of the inner reaction tube 12 is supported by the step 40.

In addition, the bottom surface of the lower flange 24 assembled at the lower ends of the first external cooling tube 16 and the second external cooling tube 20 and the upper surface of the upper flange 34 of the discharge block 30 are sealed. The member 18 is joined.

In the thermal plasma reactor of the present invention having the above-described configuration, the space between the inner reaction tube 12 and the outer reaction tube 14 of the double tube reactor 10 is a reactor gas flow passage supplied from the reactor gas supply port 16a ( 13), and the space between the outer diameter of the outer reaction tube 14 and the inner diameter of the first outer cooling tube 16 becomes the waste body flow passage 15 supplied from the waste body supply port 16b. The space between the outer diameter of the cooling tube 16 and the inner diameter of the second outer cooling tube 20 becomes the cooling water flow passage 19.

Looking briefly the operating flow of the thermal plasma reactor of the present invention made of such a configuration.

The plasma torch using the nitrogen discharge is applied to the reactor inlet of the reactor in the state connected to the plate 26 for connecting the plasma torch, that is, the torch flame of the high speed jet toward the inner and outer reaction tubes 12 and 14.

In addition, when the gas to be decomposed such as HFC-23, CHF _3, etc. is supplied through the waste gas supply port 16b, the gas flows to the upper end of the external reaction tube 14 along the waste gas flow passage 15. Supplied.

In addition, when steam and air, which is a reactor body necessary for decomposition of the waste body, are supplied through the reactor body supply port 16a, the reactor body also reacts through the communication port 14a formed at the lower end of the external reaction tube 16. It is supplied to the upper end of the internal reaction tube 14 along the gas flow passage 13.

Thus, the waste body and the reaction gas are mixed with each other in the upper space of the inner and outer reaction tubes (12, 14) and thermally decomposed by a torch flame, and the decomposed gas heat is discharge pipe 32 of the discharge block 30. Is discharged through.

Of course, the cooling water flowing through the second external cooling tube 20 is cooled to the inner region of the first external cooling tube 16 in a high temperature state, and the auxiliary cooling tube 39 of the discharge block 30. The cooling water flowing therein cools the exhaust gas flowing in the discharge pipe 32.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Example 1

In order to investigate the performance of the plasma decomposition efficiency according to the internal shape of the thermal plasma reactor of the present invention, the internal reaction tube 12 and the external reaction tube 14 of the double tube reactor 10, the first external cooling tube 16 The diameter of the 2nd external cooling pipe 20 was kept constant at 32 mm, 52 mm, 72 mm, and 103.6, respectively, and the ratio of S = A / C was changed from 0.5 to 1.75.

That is, for the plasma decomposition efficiency experiment according to the internal shape of the thermal plasma reactor, the plasma torch outlet (the position where the torch connecting plate 26 having the ejection hole in the center) and the inlet of the internal reaction tube 12 The reactor was manufactured while changing the ratio of S = A / C, which is a ratio of the distance (A) and the diameter (C) of the internal reaction tube 12, to 0.5, 1.125, and 1.75, respectively. As shown.

The external reaction tube 14 and the first external cooling tube 16 of the double tube reactor 10 may be manufactured in a range that does not affect the diameter (C) change of the internal reaction tube 12 and the amount and flow of the reactor body. Can be.

At this time, in order to measure the outlet gas temperature of the reactor according to the change in the internal shape of the reactor, the bottom 5cm of the reactor as the temperature measurement position of the reactor measured under the experimental conditions (5cm bottom discharge block of the inner reaction tube 12 (30) Thermocouple (not shown).

Experimental Example 1

In order to investigate the actual laboratory performance on the velocity and temperature distribution and the plasma decomposition rate in the plasma reactor irradiated by the above-described transfer simulation, while changing the S = A / C ratio of the reactor according to Example 1 from 0.5 to 1.75 Plasma decomposition efficiency was evaluated by injecting HFC-23 into the waste passage through the waste feed port.

At this time, the thermal plasma power of the plasma torch used was 7.5kW (50A, 150V), the capacity of nitrogen gas for plasma formation was 50 slpm.

In addition, the basic flow rate of HFC-23 used as waste decomposition products is 2.5 slpm, and the flow rate of water vapor and air for complete decomposition is 3.25 slmp (2.61), which is 30% more than the amount of water vapor and air required for the theoretical decomposition of HFC-23. ml aq / min), 7.74slpm.

Then, the temperature of the gas after passing through the reactor outlet temperature and the auxiliary cooling tube of the discharge block was measured for temperature measurement to verify the efficiency of the reactor.

Degradation rate analysis for HFC-23 was performed by gas chromatography (HP 6890) Flame Ionization Detector (FID) and the analysis conditions were as follows.

Using the gas chromatography flame ionization column with HP5-MS (30m × 0.25mm × 0.25㎛), the column has an inlet temperature of 120 ° C, pressure 23.64 psi, split ratio of 5: 1, and hydrogen gas. The flow rate was maintained at 11 ml / min, oven temperature 180 deg. C, column flow rate 1.1 cc / min, and detector temperature 250 deg.

The results according to Experimental Example 1 are as described in Table 1 below.

As shown in Table 1 above, in the plasma decomposition efficiency experiment according to the inner shape of the reactor prepared according to Example 1, the reactor outlet temperature was in the range of about 1000 ~ 1300 ℃, the efficiency at each condition after the plasma pyrolysis It was found that the efficiency was 99.5% or more.

However, as shown in the photograph of FIG. 3, when the ratio of S (= A / C) is 1.75, the reaction gas is incompletely mixed, and the unreacted carbon and metal oxides are larger than when the ratio of S (= A / C) is 1.125. It was observed that a little more formation and deposition inside the reactor were observed. Also, when the ratio of S (= A / C) is 0.5, that is, when the torch flame is close to the reactor, the reactor is decomposed due to the influence of the flame. Melting, a phenomenon that a hole (hole) and a metal oxide is generated in the reactor.

In addition, as shown in Table 1, the temperature of the reactor obtained through Experimental Example 1 was found to be almost identical to the numerical value obtained in the above-described transfer simulation process.

Example 2

In Example 1 and Experimental Example 1, the decomposition performance of the reactor was tested by making a reactor while changing the internal shape. In Example 2, the inner reaction tube 12 and the outer reaction tube 14 of the double tube reactor 10 were tested. In order to evaluate the performance by measuring the state of the inside of the reactor, the exit temperature and the decomposition rate in the plasma pyrolysis due to the height difference of the plasma torch outlet (torch connection plate having a blowout hole in the center as shown in FIG. 4). (26) is installed) to adjust the distance (B) from the external reaction tube 14 to produce a reactor.

That is, as shown in the actual production photo of FIG. 5, the plasma torch outlet of the double tube reactor 10 (the position where the torch connecting plate 26 having the ejection hole is mounted) and the internal reaction tube 12 are formed. Internal reaction tubes were manufactured based on the ratio S (S = A / C) = 1.125, 1.75 to the inlet, and the diameters of the internal and external reaction tubes (12, 14) were kept constant at 32 mm and 52 mm. The reactor was fabricated by adjusting the distance (B) from the plasma torch outlet to the tip of the external reaction tube (14) to 16 mm, 26 mm, and 56 mm.

Experimental Example 2

In the reactor manufactured according to Example 2, that is, the S = A / C ratio was changed to 1.125 and 1.75, and the reactor (B) from the plasma torch outlet to the tip of the external reaction tube was adjusted to 16mm, 26mm, 56mm Plasma decomposition efficiency was evaluated.

Thus, Experimental Example 2 was tested in the same manner as in Experimental Example 1, so that the results can be compared with the experimental results of Example 1 according to the change in the internal shape of the reactor, and the results are shown in Table 2 below.

As shown in Table 2 above, the reactor outlet temperature in the plasma pyrolysis efficiency test according to the change in the shape of the external reaction tube (adjustment of the distance (B) from the plasma torch outlet to the tip of the external reaction tube) ranges from about 1000 to 1100 ° C. The efficiency in each condition after plasma pyrolysis was about 99.5%.

However, under the condition that the ratio of S (= A / C) is 1.75 and 1.125, as the distance B from the plasma torch outlet to the external reaction tube increases, the decomposition efficiency increases and the temperature of the reactor outlet gas decreases. It was found that this can induce a complete gas decomposition by forming a mixed region of reaction gas at a part where HFC-23 and steam meet.

In addition, as shown in the photograph of FIG. 5, at distances B and 16 and 26 mm, erosion occurred only on one end of the inner reaction tube, which was caused by incomplete mixing of HFC-23 and steam. The effect of the high temperature of the HF and the plasma flame can be seen.

When the distance B increases, the condensation of steam by the external second external cooling tube occurs, and the contact between the steam and the HFC-23 occurs at a low temperature, which is in contact with the second external cooling tube. Deposition of unreacted HC (hydrocarbon) was observed on the wall of the external reaction tube.

As a result of Experiment 2 for Example 2, it was found that the efficiency of the reactor was the best in the ratio S (= A / C) of 1.125 and the distance B = 56 mm.

Example 3

The structure of the reactor was prepared in the same manner as in Examples 1 and 2, except that the inner and outer reaction tubes 12 and 14 were respectively Inconel, Incoloy, Silicon Carbide (SiC), and Tungsten Carbide ( It was manufactured separately by applying it as WC) material.

Experimental Example 3

The degree of corrosion and erosion of the inner and outer reaction tubes of the reactor manufactured according to Example 3 was experimentally investigated, and the erosion state of the reactor was experimentally confirmed while descending axially from the upper end of the reactor.

The experimental method of Experimental Example 3 carried out plasma pyrolysis as the experimental conditions mentioned in Experimental Example 1, which is an experimental example of Example 1, and measured the reactor thickness before and after pyrolysis to investigate the change, and also to change the reactor in the axial direction. Figures were examined before and after the thickness, the results are as shown in Table 3 below.

In Table 3 below, the end means the end of the inner reaction tube closest to the plasma torch, and the thickness change was measured from the end to the 2cm part with little change in thickness.

According to the experimental results of Table 3, Inconel was the most resistant to corrosion in terms of material, and it was found that silicon carbide was the weakest, so erosion by plasma ion collision was more important factor than chemical reaction. Could know.

In addition, when the corrosion rate was changed in the axial direction of the reactor, it was found that there was almost no change in the average thickness at 2 cm or more from the end of the internal reaction tube, so that no erosion occurred. It was found that the optimization of the reactor material to withstand the need is needed.

Analyzing the results of Examples 1, 2 and 3 as described above, the following conclusions can be obtained.

For smooth combustion of fluorine-containing gas, it is desirable to apply internal and external reaction tubes with different heights, such as siphon type, and complete mixing of reactant gases by vortex at the outlet of the plasma torch and the upper part of the reactor is very important. .

Therefore, the internal structure design of the reactor will be very important.

That is, the multi-tube geometry inside the reactor should be designed to minimize the reaction erosion caused by the collision of the reaction gas and plasma ions.

Therefore, the velocity distribution and the temperature distribution in the plasma reactor were calculated during the computer simulation. Based on this, the decomposition rate and the outlet temperature of the actual HFC-23 due to the change in the shape of the reactor through Example 1 and Experimental Example 1 were calculated. The measured values were compared with the computer simulation results, and the results were very good.

In addition, through Example 2 and Experimental Example 2, the reaction rate of the reaction gas at the distance (B) = 56 mm is best compared experimentally by comparing the actual decomposition rate of HFC-23 due to the shape change of the reactor, the outlet temperature, the reactor type, and the like. I could see that.

In addition, through Example 3 and Experimental Example 3, the corrosion rate of each material and the erosion rate of the inner and outer reaction tubes undergoing the HFC-23 decomposition reaction were investigated. As a result, Inconel metal was the most resistant to corrosion and the plasma "S Although the most appropriate decomposition rate and temperature distribution were shown at 1.125, the erosion by plasma was still a problem.

Accordingly, it is understood from Examples 1 to 3 above that there is a need for a method of maximizing the decomposition efficiency of fluorine-containing gas by high temperature plasma ions in a thermal plasma process, and protecting the reactor from corrosion and erosion and improving durability. Could.

In view of this point, a reactor was fabricated as in Example 4 below.

Example 4

4 is a view showing the reactor according to the fourth embodiment of the present invention, a cap-type replaceable part was manufactured and detachably press-fitted into the upper end of the inner reaction tube 12 of the double tube reactor 10. .

That is, the same applies to the height of the outer reaction tube 14 and the inner reaction tube 12, the hollow cap 42 is detachably inserted into the upper inner diameter of the inner reaction tube 12, the inner reaction tube ( 12) the reactor was made to have a greater height than the external reaction tube (14).

At this time, the specification of the hollow cap 42 is adopted that can apply the reactor form of S (= A / C) = 1.125 as in Example 1, the results of corrosion degree obtained in Example 3 and Experimental Example 3 The material was based on Inconel.

Experimental Example 4

As Experimental Example 4, the decomposition experiment of the fluorine-containing gas according to Experimental Example 1 was carried out under the same conditions, and thus exhibited much higher durability against erosion than the absence of a cap form. As shown in the result of Fig. 3, the erosion occurred in the cap.

However, even if the cap is eroded, since only the cap, not the entire reactor, can be replaced and used continuously, it can greatly contribute to reducing the overall cost of the reactor and improving the stability of the process.

10: double tube reactor 12: internal reaction tube
13: reactor flow passage 14; External reaction tube
14a: communication port 15: waste flow passage
16: first external cooling tube 16a: reactor gas supply port
16b: waste body supply port 18: sealing member
19: cooling water flow passage 20: the second external cooling pipe
20a: cooling water supply port 20b: cooling water discharge port
22: upper flange 24: lower flange
26: Plasma torch connection plate 30: discharge block
32: discharge pipe 34: top flange
36: lower flange 38: boss
39: auxiliary cooling pipe 39a: cooling water inlet
39b: cooling water outlet 40: step
42: hollow cap

Claims (11)

As a double tube structure having a different diameter and height, the inner reaction tube 12 and the outer reaction tube 14 forms a predetermined interval for the reactor flow passage 13 between each other overlapping double tube reactor (10);
As arranged to form a waste gas flow passage 15 at regular intervals in the outer diameter portion of the external reaction tube 14, the reactor gas and waste liquid in the reactor flow passage 13 and waste gas flow passage 15, respectively A first external cooling tube 16 having a reactor body supply port 16a and a waste body supply port 16b for supplying the lower end;
Cooling water supply port 20a which is arranged to form a cooling water flow passage 19 at a predetermined interval in the outer diameter portion of the first external cooling pipe 16, and communicates with the cooling water flow passage 19 in the upper and lower ends, respectively; A second external cooling pipe 20 having a cooling water outlet 20b formed therein;
A plasma torch connection plate 26 attached to an upper flange 22 integrally formed at an upper end of the first external cooling tube 16 and the second external cooling tube 20;
The lower ends of the inner and outer reaction tubes (12,14) is coupled to the discharge coupled to the lower flange 24 formed integrally with the lower end of the first outer cooling tube 16 and the second outer cooling tube (20). Block 30;
High efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that configured to include.
The method according to claim 1,
The upper end of the inner reaction tube 12 and the outer reaction tube 14 is a free end, the same length is adopted, the upper end of the inner reaction tube 12 to have a height higher than the outer reaction tube 14 High-efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that the separate hollow cap 42 is separably inserted and fastened.
The method according to claim 1,
The inner reaction tube 12, the outer reaction tube 14, and the plate 26 for connecting the plasma torch are made of Inconel metal, and the first outer cooling tube 16 and the second outer cooling tube 20, Ejection block 30 is a high efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that made of stainless steel 316 material.
The method according to claim 1,
The ratio of the distance (A) to the inlet of the internal reaction tube 12 and the diameter (C) of the internal reaction tube 12 from the position where the torch connecting plate 26, which is the plasma torch outlet, is mounted (S = A / C) is a high efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that it is made to be 0.5 ~ 1.75.
The method of claim 4,
The ratio of the distance (A) to the inlet of the internal reaction tube 12 and the diameter (C) of the internal reaction tube 12 from the position where the torch connecting plate 26, which is the plasma torch outlet, is mounted (S = A / C) is a high efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that the production is 1.125.
The method according to claim 1,
For the highly concentrated fluorine-containing fluorine gas pyrolysis, characterized in that the distance (B) from the position where the torch connection plate 26, which is the plasma torch outlet, is mounted in the range of 16 mm to 56 mm. High efficiency thermal plasma reactor.
The method of claim 6,
High-efficiency thermal plasma for highly concentrated fluorine-containing fluorine gas pyrolysis, characterized in that produced by setting the distance (B) from the position where the torch connection plate 26, which is the plasma torch outlet, to the tip of the external reaction tube 14 to 56 mm. Reactor.
The method according to claim 1,
The discharge block 30 is
A hollow discharge pipe 32 vertically coinciding with the hollow portion of the internal reaction tube 12;
An upper flange 34 and a lower flange 36 formed integrally with the upper and lower ends of the discharge pipe 32;
A boss portion 38 protruding upward from a position of an outer circumferential portion of the discharge pipe 32 on the upper surface of the upper flange 34;
An auxiliary cooling pipe 39 positioned between the upper flange 34 and the lower flange 36 and arranged at an outer diameter of the discharge pipe 32;
High efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that consisting of.
The method according to claim 1 or 8,
The boss portion 38 is inserted into the space between the lower end portions of the inner reaction tube 12 and the outer reaction tube 14, and the lower end of the outer reaction tube 14 is supported on the upper surface of the upper flange 34 and at the same time. The lower end of the reaction tube 12 is a high efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that supported on the step (40).
The method according to claim 1 or 8,
A sealing member (c) is formed between a bottom surface of the lower flange 24 formed at the lower ends of the first external cooling tube 16 and the second external cooling tube 20 and an upper surface of the upper flange 34 of the discharge block 30. High efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that 18) is inserted.
The method according to claim 1,
To measure the outlet gas temperature of the reactor, a high efficiency thermal plasma reactor for pyrolysis of highly concentrated fluorine-containing gas, characterized in that a thermocouple is installed at a predetermined position of the discharge block (30).

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