JP2013160456A - Decomposition treatment device of persistent substances - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple decomposition treatment device that can innocuously treat a process exhaust gas including Freon series persistent substances and silane system substances sent into a combustion cylinder body from a process exhaust gas induction port by combustion decomposition without attaching powder produced by combustion decomposition of the silane system substances on a wall surface.SOLUTION: A decomposition treatment device includes a combustible gas nozzle 36 which belches a combustible gas in the direction of a center axis line L1 of a combustion cylinder body 10 and a combustion supporting gas nozzle 35 positioning inside the combustible gas nozzle to belch a combustion supporting gas in a direction perpendicular to an inner periphery of the combustion cylinder body 10 like colliding. By controlling an amount of the combustion supporting gas so that the combustion gas and the combustion supporting gas flow down along an inner peripheral wall of the combustion cylinder body 10 at around a speed of 10 m/s or faster, the powder produced when the silane system substances are combusted and decomposed does not attach on a wall face but flies downstream. By setting a temperature inside the combustion cylinder body 10 at around 1,000°C or higher, the combustion decomposition of Freon series persistent substances also progresses.

Description

TECHNICAL FIELD The present invention relates to an apparatus for decomposing and treating refractory substances and silane-based substances by combustion, and in particular, chlorofluorocarbons contained in a process exhaust gas discharged in a gas processing step of a semiconductor manufacturing process, a liquid crystal manufacturing process or a solar cell manufacturing process. Refractory substances (PFC, CF ₄ , SF ₆ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , CHF ₃ , NF ₃ etc.) and silane-based substances (SiH ₄ , Si ₂ H ₆ , TEOS) The present invention relates to a decomposition treatment apparatus suitable for simultaneously decomposing (Si (OC ₂ H ₅ ) ₄ ), SiF _4, etc.) by combustion with high efficiency.

In a gas processing process such as a semiconductor manufacturing process, a liquid crystal manufacturing process, or a solar cell manufacturing process, generally, gas having different characteristics for each process, for example, a fluorocarbon gas containing a fluorocarbon material such as PFC, or a silane such as SiH ₄ A silane-based gas containing a system material is used. Fluorocarbons are difficult to decompose and have a particularly high global warming effect. Silanes are flammable, natural, and toxic harmful substances that are used as process exhaust gases in each process. On the other hand, after processing these substances to be harmless, they are released into the atmosphere.

A high temperature environment of about 1000 to 1500 ° C. is required for the combustion and decomposition treatment of chlorofluorocarbon-based material. On the other hand, silane-based substances are flammable or spontaneously ignited in air at room temperature, and can be decomposed by combustion at a lower temperature than chlorofluorocarbon-based difficult-to-decompose substances. The generation of SiO ₂ powder (silica powder) is inevitable. For this reason, if a cracking treatment device developed mainly for the combustion cracking treatment of chlorofluorocarbon-based difficult-to-decompose substances is used for the treatment of process exhaust gas containing a large amount of silane-based substances, the generated powder can be used in any combustion tower. It accumulates at the site, eventually causing clogging and causing the burner, which is a heat source, to misfire, or the accumulation of powder grows to block the inside of the combustion tower. If measures are taken to suppress the accumulation of powder or to scrape off the accumulated powder, the combustion temperature cannot be raised as a result, as will be described later. That is, when the combustion treatment temperature is lowered mainly for the treatment of silane-based substances, the decomposition efficiency of chlorofluorocarbon-based difficult-to-decompose substances decreases. For this reason, it is desirable that the combustion decomposition treatment of the fluorocarbon-based material and the combustion decomposition treatment of the silane material be performed using dedicated decomposition treatment apparatuses.

  In the prior art, an exhaust gas treatment apparatus has been proposed in which special measures are taken in order to exclude the produced powder from the treatment apparatus in an exhaust gas treatment apparatus in which powder is formed by combustion decomposition treatment.

  For example, in Patent Document 1, a gas such as air is ejected from the entire inner wall of the combustion chamber to prevent the generated powder from accumulating on the wall surface of the combustion chamber, and can be easily removed even when deposited. . In Patent Document 2, a burner and an air intake port are provided in the tangential direction of the inner wall of the cylindrical combustor to cause a swirling flow along the inner wall surface, thereby preventing powder from accumulating on the wall surface. In Patent Document 3, a jig (scraper) for scraping powder is provided, and this jig is moved to remove powder adhering to the combustor. In Patent Document 4, the growth of powder is prevented by flowing water inside the combustor to form a water film.

JP 10-54534 A JP 2004-69269 A JP 2008-39280 A JP 2008-161861 A

  When the means described in Patent Documents 1 to 4 are to be used in an apparatus that intends to combust and decompose both a process exhaust gas containing a fluorocarbon material and a process exhaust gas containing a silane material, there are problems to be solved respectively. Arise. As described in Patent Document 1, when a means for ejecting a gas such as air from the entire inner wall of the combustion chamber is employed, the temperature in the combustion chamber may be lowered, and the decomposition efficiency of the chlorofluorocarbon-based hardly decomposed substance is increased. Becomes difficult. As described in Patent Document 2, when a swirl flow along the inner wall surface of the combustion chamber is caused, a flow of process exhaust gas that does not come into contact with the high-temperature region is likely to be generated. It will not rise. As described in Patent Document 3, in an aspect including a metal jig (scraper) for scraping powder, the jig has a high temperature of about 1000 to 1500 ° C., which is a combustion decomposition temperature of a chlorofluorocarbon-based material. There may be cases where the environment cannot be tolerated. In that case, there is a possibility that the metal jig may be melted or melted down, thereby hindering the powder scraping. The jig (scraper) may be formed of a ceramic material that can withstand high temperatures, but the material becomes brittle and the strength to scrape the powder cannot be obtained. As described in Patent Document 4, when a means for forming a water film by circulating water inside the combustor is adopted, it is naturally difficult to form a high temperature region in the combustor. There is a risk that the decomposition efficiency will not increase.

  Moreover, even if any means is adopted, the structure becomes extremely complicated, the manufacturing cost increases, the maintenance is not easy, and it is difficult to stably operate the decomposition processing apparatus for a long time.

  The present invention has been made in view of the circumstances as described above, and a process containing a fluorocarbon-based decomposable substance while the configuration as an apparatus is extremely simplified, the manufacturing cost can be reduced, and maintenance is easy. It is an object of the present invention to provide a decomposition apparatus for a hardly decomposable substance capable of detoxifying both exhaust gas and process exhaust gas containing a silane-based substance simultaneously and effectively by combustion decomposition.

The present inventors have conducted a number of experiments to solve the above-mentioned problems, and the silane-based material is formed in the combustion cylinder capable of forming a high temperature environment of about 1000 to 1500 ° C. capable of burning and decomposing the chlorofluorocarbon-based hardly decomposed material. When the process exhaust gas containing is introduced from the process exhaust gas introduction port, the silane-based material is combusted and decomposed in a short time from the introduction to form SiO ₂ powder, but it burns along the inner peripheral surface of the combustion cylinder By generating an air flow toward the downstream of about 10 m / s in the central axis direction of the cylinder, the formed powder is discharged to the outside of the combustion cylinder together with the air current without adhering and depositing on the inner peripheral surface of the combustion cylinder. I knew I could do it. The velocity of the airflow at which SiO ₂ does not adhere and accumulate depends on the use state of the process exhaust gas containing the silane-based material. For example, in the example shown in FIG. 4 of Japanese Patent Laid-Open No. 2003-340226, 7 m / s Even if compared with this document, about 10 m / s in the present invention is considered to be a sufficient flow velocity.

  In addition, by analyzing the simulation, the position of the combustible gas nozzle that forms the flame forming means provided on the closed wall of the combustion cylinder and the position of the combustion-supporting gas nozzle and the positional relationship thereof are specified, so that the inner circumference at the upstream position of the combustion cylinder is determined. On the surface, an air flow toward the downstream of about 10 m / s or more in the direction of the central axis of the combustion cylinder can be formed. It was confirmed that a temperature environment could be formed. The present invention has been made based on the above findings and confirmed matters.

  That is, a decomposition apparatus for a hardly decomposable substance according to the present invention includes a combustion cylinder having a closed wall at one end, flame forming means provided on the closed wall of the combustion cylinder, and the closed wall of the combustion cylinder. Or a process exhaust gas introduction port provided near the process exhaust gas introduction port for introducing process exhaust gas containing the hardly decomposed substance into the combustion cylinder, wherein the flame forming means includes the combustion cylinder A plurality of combustible gas nozzles for ejecting combustible gas into the body, and a plurality of combustible gas nozzles for ejecting combustible gas into the combustion cylinder, wherein the plurality of combustible gas nozzles are the combustion cylinder. A plurality of the combustion-supporting gas nozzles are disposed around the central axis of the body and inject the combustible gas in a direction along the central axis of the combustion cylinder. Located around the central axis at the side, and wherein the being adapted to eject a combustion assisting gas in the direction perpendicular to the flow of combustible gas ejected from the combustible gas nozzle.

  In the decomposition apparatus for persistent substances according to the present invention, the combustion-supporting gas ejected from the combustion-supporting gas nozzle collides with the inner peripheral wall of the combustion cylinder at a substantially vertical angle. Combustible gas is ejected from the combustible gas nozzle in the direction along the central axis of the combustion cylinder into the combustion cylinder. Under the influence, the combustion-supporting gas after the collision flows downstream at a high speed. . By setting the inner diameter of the combustion cylinder and the injection speed of the combustion-supporting gas from the combustion-supporting gas nozzle experimentally or by analysis through simulation, an air flow toward the downstream of about 10 m / s or more can be formed.

  Further, by appropriately setting the combustion conditions of the flame forming means, a high temperature environment of about 1000 to 1500 ° C. can be formed in the combustion cylinder along the inner peripheral surface of the combustion cylinder. Thereby, even when the process exhaust gas from the process exhaust gas introduction port contains a chlorofluorocarbon-based hardly decomposable substance, the detoxification by combustion decomposition can be surely performed.

Under these conditions, when process exhaust gas containing silane-based materials flows into the combustion cylinder, or in the process exhaust gas that has been continuously treated, silane-based materials are now included in addition to chlorofluorocarbon-based persistent decomposition materials. In some cases, the silane-based material has a low decomposition temperature and may have a self-combustibility, and therefore, the combustion decomposition process proceeds immediately after inflow. At the same time, SiO ₂ powder is produced. However, at the upstream position of the combustion cylinder, as described above, the air flow toward the downstream of about 10 m / s or more is formed by the combustion supporting gas or the combustion gas after the combustion reaction of the combustible gas and the combustion supporting gas. Thus, the generated SiO ₂ powder does not adhere to the inner peripheral wall of the combustion cylinder, and is quickly discharged downstream. Therefore, it is possible to reliably avoid troubles in the burner and the combustion cylinder caused by the generated powder adhering and depositing in the combustion cylinder.

  The apparatus for decomposing a hardly decomposable substance according to the present invention does not include any special means for preventing the powder generated when the silane-based substance is subjected to the combustion decomposing process from adhering to the inner peripheral wall of the combustion cylinder. Structurally, the combustible gas nozzle and the combustible gas nozzle constituting the flame forming means for forming the combustion flame necessary for the combustion decomposition treatment of the hardly decomposable substance are located near the closed wall of the combustion cylinder. The problem to be solved is solved by setting the direction of the combustible gas nozzle and the combustion-supporting gas nozzle in the specific direction described above. For this reason, the overall structure of the decomposition apparatus for hardly decomposed substances is extremely simple, and the manufacturing cost can be reduced and the subsequent maintenance is extremely easy.

  Further, in the apparatus for decomposing a hardly decomposable substance according to the present invention, it is not necessary to dispose a jig (scraper) for scraping powder in the combustion cylinder, and the metal jig is used even in a high temperature environment of about 1000 to 1500 ° C. There is no particular problem of destroying. Furthermore, since the process exhaust gas, the combustible gas, and the combustion support gas, which are gases to be treated, do not enter the combustion cylinder, the temperature inside the combustion cylinder does not decrease due to other external factors. The gas stream line in the combustion cylinder is not disturbed. Therefore, a desired high-temperature processing environment can be formed and maintained in the combustion cylinder, so that a high decomposition process can be achieved. Furthermore, the gas stream line is basically a simple flow downstream along the inner wall of the combustion cylinder, and a circulating flow can also be expected at the center of the combustion cylinder, so that the process exhaust gas passes through the high temperature region. Can be reliably avoided, and in particular, the decomposition efficiency of the process exhaust gas containing the chlorofluorocarbon-based hardly decomposed substance is improved.

  In a preferred aspect of the decomposition processing apparatus for hardly decomposed substances according to the present invention, the combustible gas nozzle and the combustion-supporting gas nozzle are alternately arranged around the central axis of the combustion cylinder. In this aspect, it is possible to avoid the combustion-supporting gas from colliding with the combustible gas immediately after ejection, and to ensure the stability of the flame.

  In another aspect of the decomposition processing device for a hardly decomposable substance according to the present invention, a second combustion-supporting gas nozzle that ejects combustion-supporting gas in a direction along the central axis is further provided at the center of the combustion cylinder. Features. In this aspect, it becomes easier to supply more combustion-supporting gas into the combustion cylinder, so that the combustion range of the combustible gas can be set wider, and the degree of freedom of the gas stream line is increased in the combustion cylinder. Therefore, it is easy to form an appropriate combustion field in the combustion cylinder according to the total amount of process exhaust gas that is a gas to be treated and the amount of hardly decomposed substances contained therein.

  In the apparatus for decomposing a hardly decomposable substance according to the present invention, the number and the installation position of the process exhaust gas introduction port are arbitrarily set on the condition that the combustion supporting gas is in the vicinity of the region where it collides with the inner peripheral wall of the combustion cylinder. It may be. In one aspect, the process exhaust gas introduction port is disposed in an inner region of the closed wall from the combustion-supporting gas nozzle. In another aspect, preferably two or more process exhaust gas introduction ports are arranged in a region outside the combustion-supporting gas nozzle of the closed wall. In another aspect, preferably, two or more process exhaust gas introduction ports are arranged on the peripheral wall of the combustion cylinder close to the closed wall. When two or more process exhaust gas introduction ports are arranged, process exhaust gases of different components from different work locations can be safely processed in the combustion cylinder without the danger of premixing process exhaust gases. It becomes possible to do.

  In the apparatus for decomposing a hardly decomposable substance according to the present invention, examples of the combustible gas include city gas called 13A, LPG, methane, and hydrogen. Examples of the combustion-supporting gas include air, pure oxygen, and oxygen-enriched air. Therefore, the combustion may be pure oxygen combustion or oxygen enriched combustion. In any case, in order to obtain a gas flow at a desired speed on the peripheral wall of the combustion cylinder by collision of the combustion-supporting gas, it is necessary that at least the combustible gas ejection flow rate <the combustion-supporting gas flow rate. It becomes. Further, the volume ratio of the combustible gas and the combustion-supporting gas is about 1:10 for methane: air, about 1: 2 for methane: oxygen, about 1:25 for LPG: air, and LPG: For oxygen, it is necessary to be about 1:25, and for hydrogen: air, it is about 2: 5. In order to make the combustion reaction more complete, it is desirable to increase the combustion-supporting gas slightly more than this volume ratio. By satisfying these relationships, the intended purpose can be achieved.

  The number and the diameter of the combustible gas nozzles and the combustion-supporting gas nozzles can be arbitrarily set as long as the relationship between the jetting flow velocity and the jetting volume of the combustible gas and the combustion-supporting gas is satisfied.

  Further, when the second combustion-supporting gas nozzle is provided, the combustion-supporting gas nozzle and the second combustion-supporting gas nozzle are on the same combustion-supporting gas supply pipe. Preferentially, it is desirable to arbitrarily set the number and the diameter of the second combustion-supporting gas nozzles.

According to the apparatus for decomposing a hardly decomposable substance according to the present invention, the process exhaust gas containing a chlorofluorocarbon-based hardly decomposable substance and silane can be reduced while the structure as the apparatus is extremely simplified and the manufacturing cost can be reduced. Both of the process exhaust gas containing the system material can be detoxified by combustion decomposition simultaneously and effectively without the adhesion of the powder (SiO ₂ ) generated by decomposition.

The figure which shows the whole of one form of the decomposition processing apparatus of the hardly decomposed substance by this invention in a cross section. The perspective view which removes a part of combustion cylinder and shows the closed wall vicinity of a decomposition processing apparatus. The figure which shows the closed wall vicinity of a decomposition processing apparatus with a cross section perpendicular | vertical to the central axis of a combustion cylinder. The figure which shows a decomposition processing apparatus in the cross section which follows the aa line of FIG. The figure equivalent to FIG. 1 which shows the other form of a decomposition processing apparatus. The figure equivalent to FIG. 1 which shows the further another form of a decomposition processing apparatus. Each dimension of the decomposition processing apparatus modeled by simulation is shown.

Hereinafter, the present invention will be described based on embodiments with reference to the drawings.
[First Embodiment]
1 to 4 show a first embodiment of a decomposition apparatus for hardly decomposed substances according to the present invention. The decomposition processing apparatus A1 includes a combustion cylinder 10 and a closing wall 20 that closes one end of the combustion cylinder 10. A flame forming means 30 and a process exhaust gas introduction port 40 are attached to the closing wall 20. ing.

  The combustion cylinder 10 is a cylindrical cylinder, and the inside is formed of a ceramic refractory material (castable) that can withstand a high temperature of about 1600 ° C. One end of the combustion cylinder 10 is closed by the closing wall 20, and the other end is open. The closing wall 20 is also made of the same material as the combustion cylinder 10. In the illustrated example, the closing wall 20 is fixed to the end of the combustion cylinder 10 by a fastening screw 11. However, a horizontal flange is provided on both ends, and the flanges are fixed together by appropriate fixing means. Also good.

  A first circular hole 21 is formed in the closing wall 20 so as to have the same center line as the central axis L <b> 1 of the combustion cylinder 10 when the closing wall 20 is fixed to the end of the combustion cylinder 10. An appropriate number (four in the figure) of second circular holes 22 are formed outside the first circular holes 21. As shown in FIG. 1, flame forming means 30 is fixed and sealed in the first circular hole 21 in an inserted state, and a process exhaust gas introduction port 40 is attached to each second circular hole 22.

  The flame forming means 30 is a member having a double-pipe structure having a cylindrical inner tube 31 and an outer tube 32 that have the same central axis L2, and the outer diameter of the outer tube 32 is formed on the closed wall 20 described above. Is approximately equal to the diameter of the first circular hole 21. The upper end side and the lower end side of the inner tube 31 are closed, and the upper end side and the lower end side of the outer tube 32 are also closed. The closed lower end 33 of the outer tube 32 is positioned higher than the closed lower end 34 of the inner tube 31. Two or more (eight in the illustrated example) first openings 35 are formed in the peripheral side wall of the inner tube 31 extending downward from the position of the lower end 33 of the outer tube 32 as shown in FIG. Is formed perpendicularly to the central axis L2 and in a radial direction so that the closed surface of the lower end 33 of the outer tube 32 is located between the first openings 35, 35 formed on the peripheral side wall of the inner tube 31. Thus, two or more (eight in the illustrated example) second openings 36 are formed in the same direction as the central axis L2.

  The flame forming means 30 is inserted into the first circular hole 21 formed in the closing wall 20 in a posture in which the center axis L2 coincides with the center axis L1 of the combustion cylinder 10, and is fixed and sealed by appropriate means. Worn. In the fixed state, the closing surface which is the lower end 33 of the outer tube 32 is located at the same position as or lower than the lower surface position of the closing wall 20. The formed second opening 36 faces the same direction as the central axis L1 (L2). In this state, the first opening 35 formed on the peripheral side wall of the inner tube 31 faces the direction orthogonal to the central axis L1 (L2), that is, the direction perpendicular to the inner peripheral surface of the combustion cylinder 10.

  With the flame forming means 30 attached to the closed wall 20 that closes one end of the combustion cylinder 10 as described above, a combustion-supporting gas (for example, air or pure oxygen) is sent into the inner pipe 31. Then, the fed combustion-supporting gas is ejected from the first opening 35 formed on the peripheral side wall of the inner pipe 31. That is, the first opening 35 functions as a combustion-supporting gas nozzle. Further, a combustible gas (for example, city gas 13A) is fed into the outer pipe 32, and the fed combustible gas is ejected from a second opening 36 formed on the closed surface of the outer pipe 32. That is, the second opening 36 functions as a combustible gas nozzle.

  In other words, a plurality (eight in the illustrated example) of combustible gas nozzles (second openings 36) are located around the central axis L <b> 1 of the combustion cylinder 10, and the combustible gas is contained in the combustion cylinder 10. Are ejected in a direction along the central axis L1. In addition, a plurality (eight in the illustrated example) of combustion-supporting gas nozzles (first opening 35) are positioned around the central axis L1 of the combustion cylinder 10 inside the combustible gas nozzle (second opening 36). The combustion-supporting gas is ejected in a direction perpendicular to the flow of the combustible gas ejected from the combustible gas nozzle (second opening 36). The jetted combustion-supporting gas collides in a direction perpendicular to the inner peripheral surface of the combustion cylinder 10.

  Although not shown, an opening in the direction along the central axis L1 of the combustion cylinder 10 can be formed in the closed lower end 34 of the inner tube 31, and the combustion-supporting gas can be ejected therefrom. In this case, the opening formed in the closed lower end 34 of the inner pipe 31 functions as a second combustion-supporting gas nozzle. In this aspect, the combustion-supporting gas nozzle and the second combustion-supporting gas nozzle are provided on the same combustion-supporting gas supply pipe, and the combustion-supporting gas and the second combustion-supporting gas nozzle ejected from the combustion-supporting gas nozzle are provided. The second combustion-supporting gas that is ejected from the fuel is made to have a trade-off relationship between the increase and decrease, and the jet flow velocity and the ejection volume of the combustion-supporting gas that is ejected from the combustion-supporting gas nozzle are given priority. It is desirable to set the number and diameter of the two combustion-supporting gas nozzles.

  Four process exhaust gas introduction ports 40 for introducing process exhaust gas from different processing apparatuses are attached to each of the four second circular holes 22 described above. The closing wall 20 is provided with a conventionally known ignition means (not shown).

  During the combustion treatment of the process exhaust gas, for example, city gas is supplied into the combustion cylinder 10 from the combustible gas nozzle (second opening 36) and air is supplied from the combustion-supporting gas nozzle (first opening 35), for example. In addition, each supply amount can be calculated | required by calculation based on the quantity and kind of process exhaust gas to process. Air from the combustion-supporting gas nozzle (first opening 35) collides in a direction perpendicular to the inner peripheral surface of the combustion cylinder 10. The speed at the time of collision and flowing down along the inner peripheral surface can be determined by the supply pressure and volume of the combustion-supporting gas and the diameter of the combustion-supporting gas nozzle (first opening 35). Preferably, these values are set so that the speed at the time of collision is about 10 m / s or more.

  The combustible gas is mixed with the combustion-supporting gas and starts to burn. The combustion gas (combustion flame) and the combustion-supporting gas that has not participated in the combustion become simple gas flow lines along the inner peripheral surface of the combustion cylinder 10, and in the direction of the central axis L1 of the combustion cylinder 10. It flows down at high speed. In the process, combustion becomes serious and a high temperature region is formed along the inner peripheral surface of the combustion cylinder 10. By setting the supply conditions of the combustion-supporting gas and the combustible gas, a high temperature environment of about 1000 to 1500 ° C. can be easily formed. At the same time, since a circulating flow is also generated in the center of the combustion cylinder 10, it is ensured that the process exhaust gas flowing in from the process exhaust gas introduction port 40 is prevented from flowing through the high temperature region of about 1000 to 1500 ° C. can do.

  In the illustrated example, the combustion-supporting gas nozzle (first opening 35) and the combustible gas nozzle (second opening 36) are formed so as not to overlap in the radial direction. Since the combustible gas does not collide immediately after being blown out from the nozzle and is mixed and ignited in the vicinity of the inner peripheral wall of the combustion cylinder 10, misfire due to blow-off can be prevented, and combustion stability is also improved.

Under such a combustion state, when the process exhaust gas containing the silane-based material flows into the combustion cylinder 10, or the silane-based material is added to the continually treated process exhaust gas in addition to the chlorofluorocarbon-based hardly decomposed material. As described above, since the decomposition temperature of the silane-based substance is low when it is contained, the combustion decomposition process proceeds immediately after flowing into the combustion cylinder 10 to generate SiO ₂ powder. The However, as described above, an upstream airflow of about 10 m / s or more is formed at the upstream position of the combustion cylinder 10, and the generated SiO ₂ powder adheres to the inner peripheral wall of the combustion cylinder 10. Instead, it is quickly discharged downstream. As a result, the generated powder adheres to the combustion cylinder 10 to cause clogging and cause a misfire of the burner as a heat source, or the accumulation of powder grows to block the inside of the combustion cylinder 10. Trouble can be avoided reliably.

[Second Embodiment]
FIG. 5 shows a second embodiment of the decomposition apparatus for hardly decomposed substances according to the present invention. In this decomposition treatment apparatus A2, one process exhaust gas introduction port 40 passes through the inner pipe 31 constituting the flame forming means 30 and opens into the combustion cylinder 10, and the closed wall 20 It differs from decomposition | disassembly processing apparatus A1 shown in FIGS. 1-4 by the point by which the 2 circular holes 22 are not formed. In this embodiment, the second combustion-supporting gas nozzle is not provided. Other configurations are the same as those of the decomposition processing apparatus A1, and the same reference numerals are given, and descriptions thereof are omitted. Even in this form, the state of the combustion flame formed in the combustion cylinder 10 is the same as that in the case of the decomposition treatment apparatus A1, and the effect of decomposition of the same hardly decomposed substance and the effect of suppressing the adhesion / deposition of the powder are obtained. can get.

[Third Embodiment]
FIG. 6 shows a third embodiment of the decomposition processing apparatus for hardly decomposed substances according to the present invention. This decomposition treatment apparatus A3 is further different from the decomposition treatment apparatus A2 shown in FIG. 5 in that two or more process exhaust gas introduction ports 40 are arranged on the peripheral wall of the combustion cylinder 10 close to the closed wall 20. It is different. Other configurations are the same as those of the decomposition processing apparatus A2, and the same reference numerals are given, and descriptions thereof are omitted. Even in this form, the state of the combustion flame formed in the combustion cylinder 10 is the same as that in the case of the decomposition treatment apparatus A1, and the effect of decomposition of the same hardly decomposed substance and the effect of suppressing the adhesion / deposition of the powder are obtained. can get. In the decomposition treatment apparatus A3 shown in FIG. 6, the process exhaust gas introduction port 40 penetrating the inner pipe 31 can be omitted.

[Verification by simulation]
Next, a simulation performed by the present inventors will be described. In the simulation, the decomposition processing apparatus A1 having the form shown in FIGS. 1 to 4 was used as a model. However, an air outlet (diameter 7.7 mm) was also provided as a second combustion-supporting gas nozzle at the closed lower end 34 of the inner tube 31. As shown in FIG. 8, the dimensions of each member are as follows: the diameter d1 of the inner peripheral wall portion of the combustion cylinder 10 is 165 mm, the diameter d2 of the process exhaust gas introduction port 40 is 41.2 mm, and the process exhaust gas introduction ports 40 and 40 facing each other. Distance between centers d3 = 111.6 mm, diameter of closed lower end 34 of inner tube 31 = 34.4 mm, diameter of closed lower end 33 of outer tube 32 = 40 mm, from closed lower end 33 of outer tube 32 The distance to the closed lower end 34 of the inner tube 31 is 15.5 mm, the diameter d4 of the first opening 35 (flammable gas nozzle) formed on the peripheral side wall of the inner tube 31 is 7.7 mm, the lower end of the outer tube 32 The diameter d5 of the second opening 36 (flammable gas nozzle) formed on the closed surface was 3 mm. Further, the length of the combustion chamber formed on the inner peripheral surface of the combustion cylinder 10 was set to 700 mm.

The combustible gas was city gas 13A, and the flow rate was 50 (L / min). The combustion supporting gas was air and the flow rate was 600 (L / min). Also, using _{N 2} alone gas as a diluent gas corresponding to the process exhaust gas and the flow rate 500 and (L / min). As the analysis code, a general-purpose three-dimensional thermal fluid analysis code Fluent 6.3 was used on a PC cluster manufactured by NEC. The flow was assumed to be a three-dimensional incompressible turbulent flow, and the analysis considering combustion and radiation was performed for a constant flow rate.

  As a result, it is confirmed that a simple gas flow line (flame flow) is formed along the inner peripheral surface of the combustion cylinder 10, and it can be confirmed that a circulating flow from the inner peripheral surface to the center portion is also generated. It was. In addition, it was confirmed that a flow velocity of 10 m / s or more could be secured from the closed upstream end to about 40 cm. Furthermore, it was confirmed that a temperature environment of 1000 ° C. or higher was formed in the combustion chamber formed on the inner peripheral surface of the combustion cylinder 10.

From the above simulation results, by using the decomposition treatment apparatus according to the present invention, by performing combustion decomposition treatment of process exhaust gas containing chlorofluorocarbon-based hardly decomposed substances, process exhaust gas containing silane-based substances, and process exhaust gas containing both of them Both can be rendered harmless by combustion, and at the same time, even if the silane-based material is decomposed by combustion to form SiO ₂ powder, it does not adhere to and deposit on the wall of the combustion chamber, etc. It can be seen that it is possible to continue the process.

[Verification by combustion experiment]
1. Combustion decomposition treatment of process exhaust gas containing chlorofluorocarbon using a decomposition treatment apparatus A that is the same as the apparatus size in the simulation, which is the decomposition treatment apparatus A for the hardly decomposable substance shown in FIGS. The experiment was conducted. Table 1 shows the experimental conditions and the CFC decomposition rate. C ₂ F ₆ and SF ₆ were used as chlorofluorocarbon-based persistent substances. Nitrogen N ₂ was used as a dilution gas. In the experiment, the decomposition rate of C ₂ F ₆ and SF ₆ was calculated by (1− [the amount of chlorofluorocarbon at the outlet] / [the amount of chlorofluorocarbon at the inlet]) × 100, which was defined as the “fluorocarbon decomposition rate”.

The experiment 1 is performed under substantially the same conditions as the simulation described above, but a high CFC decomposition rate of 98% is obtained. Ease of decomposition is C ₂ F ₆ (about 800 to 1000 ° C.) <SF ₆ (about 1200 ° C.) (* decomposition temperature is estimated), and a temperature environment exceeding 1200 ° C. is formed in the combustion cylinder. It is speculated that it was. Although the silane-based material was not added, it is understood that the silane-based material is more easily decomposed than the chlorofluorocarbon-based material and is naturally decomposed. Further, in the experiment, the flow velocity on the inner peripheral surface of the combustion cylinder 10 was not measured, but the flow rate ratio of the combustible gas and the combustion-supporting gas was almost the same between the simulation and the experiment. Since it has been confirmed that a flow velocity of s or more can be secured, in this experimental example, even if the silane-based material is decomposed by combustion to form SiO ₂ powder, it does not adhere to the wall surface of the combustion chamber. Obviously, it can be discharged from the combustion cylinder.

A ... Degradation processing equipment for hardly decomposable substances,
L1 ... the central axis of the combustion cylinder,
L2: the central axis of the flame forming means,
10 ... Combustion cylinder,
20 ... closed wall,
30 ... Flame forming means,
31 ... Inner pipe,
32 ... Outer pipe,
33 ... the closed lower end of the outer tube,
34 ... closed bottom end of inner tube,
35 ... 1st opening (flammable gas nozzle),
36 ... 2nd opening (flammable gas nozzle),
40: Process exhaust gas introduction port.

Claims (5)

A combustion cylinder having a closed wall at one end, flame forming means provided on the closed wall of the combustion cylinder, and a hardly decomposable substance in the combustion cylinder provided at or near the closed wall of the combustion cylinder A process exhaust gas introduction port for introducing process exhaust gas containing,
The flame forming means includes a plurality of combustible gas nozzles for ejecting a combustible gas into the combustion cylinder, and a plurality of combustion support gas nozzles for ejecting a combustible gas into the combustion cylinder. The combustible gas nozzles are positioned around the central axis of the combustion cylinder and are configured to eject the combustible gas in a direction along the central axis of the combustion cylinder. Is characterized in that the combustion-supporting gas is ejected in a direction perpendicular to the flow of the combustible gas ejected from the combustible gas nozzle and located around the central axis inside the combustible gas nozzle. Decomposition processing equipment for difficult-to-decompose substances   2. The decomposition apparatus for a hardly decomposable substance according to claim 1, wherein the combustible gas nozzle and the combustion-supporting gas nozzle are alternately arranged around a central axis.   3. The decomposition apparatus for hardly decomposed substances according to claim 1, further comprising a second combustion-supporting gas nozzle that ejects combustion-supporting gas in a direction along a central axis of the combustion cylinder.   The said process waste gas introduction port is arrange | positioned in the area | region inside the said combustion support gas nozzle of the said closed wall, The decomposition processing apparatus of the hardly decomposed substance as described in any one of Claim 1 thru | or 3 characterized by the above-mentioned.   The said process waste gas introduction port is arrange | positioned in the area | region outside the said combustion-supporting gas nozzle of the said closed wall, The decomposition processing apparatus of the hardly decomposed substance as described in any one of Claim 1 thru | or 3 characterized by the above-mentioned.

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