JP4535558B2 - Combustion exhaust gas treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a device for decomposing and releasing flammable gases, toxic gases, or gases that have a large environmental impact in semiconductor manufacturing processes. In place Related.
[0002]
[Prior art]
Many types of harmful gas components such as SiH 4 are contained in the gas discharged from the semiconductor manufacturing process. Since exhaust gas containing such components can only be released into the atmosphere after removing harmful exhaust gas components, exhaust gases are released into the atmosphere after being processed through an exhaust gas treatment device. .
[0003]
It is desirable to install such an exhaust gas treatment apparatus as close as possible to a semiconductor manufacturing apparatus that generates harmful gases.
However, since the semiconductor manufacturing apparatus is provided in a clean room and the installation space is limited, the exhaust gas processing apparatus is required to be downsized.
[0004]
In addition, since the exhaust gas components include different types of exhaust gas components and the exhaust gas components have different decomposition temperatures, it is also required to process exhaust gas components having different decomposition temperatures with one exhaust gas processing device. The Specifically, SiH4, which is a typical gas component used in semiconductor film formation processes, is highly reactive, so it can easily burn and explode, but it is used for semiconductor cleaning and etching. The PFCs that are produced are chemically stable and poor in reactivity, and their decomposition temperatures vary greatly.
[0005]
In view of these points, the present inventors have disclosed an exhaust gas passage in Japanese Patent Application No. 8-103257 as shown in FIG. A combustion nozzle 71 provided with fixed guide vanes and free rotating vanes having a predetermined structure, and an outer cylinder 72 and an inner cylinder 73, and an exhaust gas channel and a fuel gas channel arranged in a concentric circle shape as a center. Combustion cylinder 74 is used, combustion secondary air is supplied from a hole 75 provided in the bottom of the inner cylinder 73, cooling air is introduced from a hole 76 provided in a side surface of the inner cylinder 73, and A combustion type exhaust gas treatment apparatus 70 that adjusts the flow rates of the combustion secondary air and the cooling air according to the ratio of the opening surface area of the hole 75 provided in the bottom portion of the inner cylinder and the hole 76 provided in the side surface portion has been proposed.
[0006]
Furthermore, the present inventors have disclosed in Japanese Patent Application No. 10-92629 that the inner cylinder 81 shown in FIG. 8 is divided into a plurality of parts for the purpose of preventing the powder generated by the combustion decomposition of SiH 4 from adhering. The upper cylindrical member 81a is overlapped so as to cover the lower cylindrical member 81a, and the upper cylindrical member 81a is overlapped with the upper cylindrical member 81a. Combustion type exhaust gas treatment apparatus 80 in which a gap 82 is formed between the inner surface side of the cylindrical member 81a and the outer surface side of the lower cylindrical member 81a has been proposed.
[0007]
The apparatus of the embodiment shown in FIG. _Four Etc. and C ₂ F ₆ Even when the flame retardant component is included at the same time, the same nozzle can efficiently burn and decompose the flame retardant component while preventing the oxide powder from adhering to the vicinity of the nozzle. did.
[0008]
Further, the apparatus of the embodiment shown in FIG. _Four Even when processing a large amount of exhaust gas, the inner wall surface of the inner cylinder is made of SiO. ₂ It has become possible to effectively prevent the powder from being deposited.
[0009]
However, in recent years, PFCs, which are exhaust gas components having a high global warming potential and a large environmental impact, have become a problem. PFCs refer to six types of gases, CF4, C2F6, C3F8, SF6, NF3, and CHF3, and are components that have a high global warming potential and a large environmental impact.
[0010]
PFCs are gases that are chemically stable and difficult to decompose, and have different decomposition temperatures for each type. 9 and 10 are graphs showing the decomposability of PFCs measured by the present inventors. FIG. 9 shows the relationship between the temperature of CF4, C2F6, and SF6 and the decomposition performance, and FIG. Represents the relationship between diluted nitrogen content and decomposition performance.
9 and 10, it can be seen that PFCs require different decomposition temperatures for each type, and that CF4 has the highest decomposition temperature and is difficult to decompose.
[0011]
When such PFCs are decomposed and removed using the combustion type exhaust gas treatment apparatus of the embodiment shown in FIGS. 7 and 8, the decomposition temperature differs for each target exhaust gas component, so the same exhaust port in the semiconductor manufacturing process When a plurality of exhaust gas components having different properties are exhausted, a plurality of devices must be provided according to the type of the exhaust gas component to be processed, and a means for switching a device to perform processing according to the target to be exhausted must be provided. did not become. As a result, the installation space for the exhaust gas treatment device has become vast, and the switching operation has to be complicated.
[0012]
In such a case, when trying to process different exhaust gas components with the same device for the purpose of reducing the size of the exhaust gas processing device and reducing the installation space, the decomposition performance differs depending on the target exhaust gas component, so the exhaust gas component that is difficult to decompose When processing the wastewater, a large amount of fuel must be used to improve the decomposition performance.
[0013]
However, from the standpoint of preventing global warming in recent years, such as the adoption of a protocol at the Global Warming Prevention Conference (COP3), it is necessary to reduce the amount of carbon dioxide emissions that accompany combustion and fuel consumption. In order to suppress this, it has been required to improve the disassembly performance of the apparatus.
[0014]
The present invention has been made in view of the above-mentioned problems, and even with a single device, various types of PFCs can be decomposed and removed, and a combustion exhaust gas treatment device that consumes less fuel. Place The purpose is to provide.
[0015]
[Means for Solving the Problems]
The combustion exhaust gas treatment apparatus of the present invention comprises a combustion cylinder comprising an outer cylinder and an inner cylinder provided with an air introduction means, an exhaust gas flow path provided at the bottom of the inner cylinder and the exhaust gas flow path. An exhaust gas combustion apparatus having an exhaust gas combustion nozzle having a fuel gas supply passage arranged concentrically around the combustion gas exhaust gas processing apparatus, and having a pressure higher than atmospheric pressure with respect to a flame formed at an opening of the fuel gas supply passage Combustion gas injection means comprising an introduction pipe or an introduction nozzle for injecting a combustion-supporting gas having pressure And a control mechanism for switching and supplying the combustion-supporting gas according to the removed component in the exhaust gas, And the introduction pipe or the introduction nozzle is provided in the inner cylinder so that the angle Θ between the combustion-supporting gas blowing direction and the exhaust gas passage direction is 90 ° to 60 °. Features.
[0016]
The combustion-supporting gas having a pressure equal to or higher than the atmospheric pressure is preferably compressed air, compressed oxygen-enriched air, or compressed oxygen.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
An example of the combustion type exhaust gas treatment apparatus of the present invention will be described with reference to FIGS. 1 is a longitudinal sectional view showing an example of a combustion type exhaust gas treatment apparatus of the present invention, FIG. 2 is an enlarged longitudinal sectional view showing the vicinity of the combustion nozzle of FIG. 1, and FIG. 3 is a combustion state of fuel gas at an opening of the exhaust gas combustion nozzle It is a partial expansion perspective view which shows an example.
[0023]
In FIG. 1, 1 is a combustion type exhaust gas treatment device (hereinafter referred to as “exhaust gas treatment device”), 2 is an outer cylinder, 3 is an inner cylinder, 4 is a combustion cylinder, and 5 is a cylinder constituting the inner cylinder. 6 is a gap provided between the cylindrical member 5, 7 is an exhaust gas combustion nozzle (hereinafter referred to as “combustion nozzle”), and 9 is an internal combustion supporting gas. A conduit for supplying the inside of the cylinder 3, 10 is an introduction pipe provided between the conduit 9 and the inner cylinder 3, and 11 a, 11 b, and 11 c are switching of each combustion supporting gas provided in the conduit 9. Reference numeral 11 denotes a generic name of the switching valve, 12 denotes an operation panel of a control mechanism that selectively supplies a combustion-supporting gas, and 13 denotes electrical wiring connecting the switching valve 11 and the operation panel 12.
[0024]
In FIG. 1, A indicates a combustion completion part, and B indicates a cooling part.
[0025]
In FIG. 2, 21 indicates an exhaust gas flow path, 22 indicates a fuel gas supply path, 23 indicates a fuel gas supply port, 24 indicates an upper end surface of the fuel gas supply path 22, and 25 indicates a flame.
[0026]
In FIG. 3, 31 indicates the flow of the combustion-supporting gas.
[0027]
An exhaust gas treatment apparatus 1 according to the embodiment of the present invention shown in FIG. 1 is for supplying a combustion cylinder 4 comprising an outer cylinder 2 and an inner cylinder 3, a combustion nozzle 7, and a combustion-supporting gas into the inner cylinder 3. A conduit 9.
[0028]
As shown in FIG. 2, the combustion nozzle 7 has a tubular exhaust gas passage 21 and a tubular fuel gas supply passage 22 arranged concentrically around the exhaust gas passage 21. A plurality of fuel gas supply ports 23 are opened in the upper end surface 24 of the exhaust gas passage 21 so as to surround the open end portion of the exhaust gas passage 21. Further, the upper end surface 24 of the fuel gas supply path 22 is provided so as to be inclined downward toward the exhaust gas flow path 21 side, that is, to have an inclination angle β with respect to the horizontal direction. It ejects from the fuel gas supply port 23 toward the center of the exhaust gas passage 21.
[0029]
Since the front end portion of the combustion nozzle 7 is configured in this way, the fuel gas ejected from each fuel gas supply port 23 forms a plurality of dispersed flames 25 surrounding the open end portion of the exhaust gas passage 21, and Each flame 25 is directed toward the center of the opening of the exhaust gas passage 21 so that the flame 25 covers the opening of the exhaust gas passage 21. Therefore, the exhaust gas discharged from the opening of the exhaust gas passage 21 is surely exposed to the high temperature portion of each flame 25, and gives a sufficient amount of heat to heat the components to be removed in the exhaust gas to be burned and decomposed. It is done.
[0030]
The fuel gas supplied through the fuel gas supply path 22 is preferably mixed with a combustion-supporting gas such as the atmosphere in advance. When such a fuel gas is used, as will be described later, by further supplying a combustion-supporting gas from the outside of the flame 25, the flame-retardant components in the exhaust gas can be efficiently decomposed.
[0031]
The inclination angle β of the upper end surface 24 of the fuel gas supply path 22 is preferably about 30 degrees in consideration of the stability of the flame 25 and the like. However, as long as the high-temperature portion of the flame 25 can be effectively used for the treatment of exhaust gas, it can be appropriately selected even at other angles.
[0032]
The opening shape of the fuel gas supply port 23 can be an arbitrary shape such as a slit shape, a circular shape, or an elliptical shape. The arrangement of the fuel gas supply ports 23 is preferably arranged in a line in the form of a slit from the viewpoint of stabilizing the flame 25 by preventing the flame 25 from extinguishing due to a change in the fuel supply amount, backfire or the like. However, it can also be arranged in two or more rows.
[0033]
Further, the interval between the fuel gas supply ports 23 must be appropriately selected according to the diameter of the opening of the exhaust gas passage 21 and the number of the fuel gas supply ports 23, but is usually set at an interval of 1 to 10 mm. It is preferable. If it is this range, when the adjacent flames 25 overlap, the high temperature part of the flame 25 can be utilized effectively.
[0034]
In the exhaust gas treatment apparatus 1 of the present invention, the combustion nozzle 7 is provided at the bottom of the inner cylinder 3 inside the combustion cylinder 4 composed of the outer cylinder 2 and the inner cylinder 3 as shown in FIG.
In the exhaust gas treatment apparatus 1 of the present invention, since the combustion cylinder 4 is configured as a double structure and the combustion nozzle 7 is provided at the bottom of the inner cylinder 3, a necessary amount of air inside the inner cylinder 3 is obtained. Can only supply. Accordingly, it is possible to prevent the flame 25 from being disturbed and the temperature from being reduced when the atmosphere is excessively supplied to the flame 25 formed at the opening of the combustion nozzle 7, and to prevent the combustion efficiency of the components to be removed in the exhaust gas from being lowered. .
[0035]
The inner cylinder 3 is provided with air introduction means. By supplying the atmosphere to the flame 25 through the introduction means, combustion decomposition of the components to be removed in the exhaust gas can be completed, and the exhaust gas from which the components to be removed have been removed can be cooled.
[0036]
As the air introduction means provided in the inner cylinder 3, for example, the inner cylinder 3 is constituted by a plurality of cylindrical members 5, and each cylindrical member 5 is formed so that a gap is formed in the overlapping portion. It is possible to adopt a configuration in which the images are sequentially stacked upward. In the case of such a configuration, when the upper and lower tubular members 5 are overlapped, the upper tubular member 5 is overlapped so as to cover the lower tubular member 5. Since the gap 6 is formed between the inner surface side of the upper cylindrical member 5 and the outer surface side of the lower cylindrical member 5, the atmosphere is introduced from the gap 6 along the inner wall surface of the inner cylinder 3. be able to.
[0037]
When air is introduced into the inner cylinder 3 along the longitudinal direction of the inner wall surface of the inner cylinder 3 in this way, the inner wall of the inner cylinder 3 is SiO. ₂ And the like, and combustion decomposition of the components to be removed in the exhaust gas can be completed.
[0038]
There are no particular restrictions on the size of the gap 6, the number of gaps 6 (that is, how many cylindrical members 5 are used to form the inner cylinder 3), etc., but the total area of the opening 6a on the inner cylinder inner surface side of the gap 6 : A ₁ And the opening area of the exhaust part 4a of the combustion cylinder 4: A ₂ A ₁ / A ₂ It is preferable to configure the gap 6 so that the relationship of = 1.5 to 0.5 is established. In particular, A ₁ / A ₂ Is preferably approximately 1. With this configuration, SiO ₂ It is possible to reliably prevent the adhesion of powder such as, and to further increase the combustion decomposition rate of the flame-retardant component to be removed contained in the exhaust gas.
[0039]
However, the means constituting the inner cylinder 3 in the present invention is not limited to the method of overlapping the cylindrical members 5. For example, as shown in FIG. 7, means for providing a plurality of air intakes on the side wall of the inner cylinder 3 may be employed.
[0040]
The inner cylinder 3 is provided with a conduit 9 for supplying a combustion-supporting gas having a pressure equal to or higher than the atmospheric pressure into the inner cylinder 3. If comprised in this way, since an appropriate amount of combustion-supporting gas can be supplied to the flame 25 from the outside, the combustion efficiency of the flame 25 can be improved. That is, the combustion of the flame 25 is further promoted by further supplying the combustion-supporting gas to the flame 25 formed by the fuel gas mixed with the combustion-supporting gas in advance, and the component to be removed in the exhaust gas is the flame-retardant component. Even so, it can be burned efficiently.
[0041]
The combustion-supporting gas having a pressure equal to or higher than the atmospheric pressure is normally supplied to the flame 25 using 8 to 16 conduits 9 having an inner diameter of about 1 mm. However, in the present invention, the diameter and number of the conduits 9 are not limited.
[0042]
The combustion-supporting gas supplied to the inside of the inner cylinder 3 through the conduit 9 is not limited as long as the pressure is equal to or higher than atmospheric pressure. ^Five The pressure is set to Pa.
When a combustion-supporting gas having such a pressure is introduced into the inner cylinder 3 and supplied to the flame 25, the ejection speed of the combustion-supporting gas increases and the heat-transfer coefficient of the combustion-supporting gas increases. Efficiency is improved and even flame retardant components such as PFCs can be combusted and decomposed. The conduit 9 is made of a material that can withstand the pressure of the combustion-supporting gas and needs to have a structure that can withstand.
[0043]
The combustion-supporting gas having a pressure equal to or higher than the atmospheric pressure in the present invention is preferably compressed air, compressed oxygen-enriched air, or compressed oxygen. When these combustion-supporting gases are used, PFCs that cannot be combusted and decomposed by a combination of conventional fuel gas such as methane and propane and the atmosphere as the combustion-supporting gas can be efficiently combusted and decomposed. . Further, when compressed oxygen-enriched air or compressed oxygen having a pressure equal to or higher than atmospheric pressure is used as the combustion-supporting gas, even PFCs that are difficult to be decomposed by combustion can be decomposed.
However, the combustion-supporting gas of the present invention is not limited to compressed air, compressed oxygen-enriched air, and compressed oxygen, and any combustion-supporting gas can be used as long as it can promote combustion of exhaust gas components that are difficult to be decomposed by combustion such as PFCs. Gas can also be used.
[0044]
As the fuel gas, hydrogen, methane, propane, butane, ethylene, natural gas, city gas, or a mixed gas thereof is used.
[0045]
In the exhaust gas treatment apparatus 1 of the present invention, the flame 25 is set such that the angle Θ (hereinafter referred to as “introduction angle Θ”) between the direction of blowing the combustion-supporting gas and the direction of the exhaust gas passage is 90 ° to 60 °. On the other hand, it is preferable to provide the inner cylinder with means for injecting the combustion-supporting gas, and more preferably to provide the introduction angle Θ between 90 ° and 70 °.
When the introduction angle Θ is less than 60 °, the combustion efficiency of the flame retardant component in the exhaust gas is deteriorated, and the flame retardant component cannot be sufficiently removed. If the introduction angle Θ exceeds 90 °, the stability of the flame 25 is lost against changes in combustion conditions, and the tip of the combustion nozzle 7 is abnormally heated, causing a safety problem.
[0046]
As shown in FIGS. 1 and 2, specific means for injecting the combustion-supporting gas so that the introduction angle Θ is 90 ° to 60 ° includes an introduction pipe 10 between the inner cylinder 3 and the conduit 9. It is preferable to install or attach the introduction nozzle to the inner cylinder 3 to eject the combustion-supporting gas so that the introduction angle Θ is 90 ° to 60 °. The introduction pipe 10 and the introduction nozzle need to be able to withstand the pressure of the combustion-supporting gas.
In this way, since the combustion-supporting gas can be easily blown into the flame 25 within the range of the introduction angle Θ of 90 ° to 60 °, the flame-retardant removing component in the exhaust gas is burned particularly efficiently. be able to.
[0047]
However, the present invention is not limited to providing the introduction pipe or the introduction nozzle in the inner cylinder as the means for injecting the combustion-supporting gas so that the introduction angle Θ is 90 ° to 60 °. Can also be adopted.
[0048]
As shown in FIG. 1, the exhaust gas treatment apparatus 1 of the present invention preferably includes a control mechanism that switches and supplies different combustion-supporting gases having a pressure equal to or higher than atmospheric pressure into the inner cylinder 3.
For example, as shown in FIG. 1, the control mechanism includes a switching valve 11 provided in the middle of piping for transporting various combustion-supporting gases, an operation panel 12 that can select a required combustion-supporting gas, and a switching valve 11. And an electrical wiring connecting the operation panel 12 to the operation panel 12.
When such a control mechanism is provided, by operating the operation panel 12 and switching the switching valves 11a, 11b, and 11c, it is possible to easily provide a combustion-supporting gas suitable for the characteristics of the removed component in the target exhaust gas. Since it can be selected, switched, and supplied, various flame-retardant exhaust gas components can be processed by one exhaust gas processing device.
[0049]
The switching valve 11 can be incorporated in the exhaust gas treatment apparatus main body, can be provided adjacent to the exhaust gas treatment apparatus main body, or can be provided outside the clean room.
However, the control mechanism shown in FIG. 1 is only an example. Therefore, it can also be mechanically configured without using electricity.
[0050]
The combustion exhaust gas treatment method of the present invention is performed using, for example, the exhaust gas treatment apparatus 1 having the mode shown in FIGS.
In the method of the present invention, exhaust gas is supplied from the exhaust gas passage 21 into the inner cylinder 3 at the bottom of the inner cylinder 3 of the combustion cylinder 4 having the outer cylinder 2 and the inner cylinder 3. Further, fuel gas is supplied from the fuel gas supply path 22 so as to surround the exhaust gas flow path 21, and a flame 25 is formed so as to surround the exhaust gas flow path 21 at the opening of the fuel gas supply path 22.
According to this method, the flame 25 can be stably formed at the opening of the fuel gas supply path 22.
In addition, it is preferable to mix a fuel-supporting gas in advance with the fuel gas.
[0051]
In the method of the present invention, the combustion of the flame 25 is promoted by supplying a flame-supporting gas having a pressure equal to or higher than the atmospheric pressure to the flame 25, and the flame-retardant removal component in the exhaust gas is combusted and decomposed. Since the method of the present invention employs such a configuration, the combustion efficiency increases, and even flame-retardant components such as PFCs can be combusted and decomposed.
[0052]
It is necessary for the combustion-supporting gas to have a pressure equal to or higher than the atmospheric pressure. When the pressure of the combustion-supporting gas increases, the speed of the combustion-supporting gas increases and when the speed of the combustion-supporting gas increases, This is because the heat transfer coefficient of the sex gas is increased. That is, since the heat transfer coefficient α is proportional to the 1/2 power of the flow rate U of the combustion-supporting gas as shown in the equation (1), when the ejection speed U of the combustion-supporting gas increases, Since the heat transfer coefficient α is increased, the combustion efficiency of the flame-retardant component in the exhaust gas is increased even if the temperature of the flame 25 is the same.
[0053]
[Expression 1]
α ∝ U ^0.5 (1)
[0054]
In Expression (1), the relationship shown in Expression (2) is established among Nusselt number Nu, Prandtl number Pr, and Reynolds number Re, and Nusselt number Nu, heat transfer rate α, representative length χ, and gas transfer rate. The relationship shown in Equation (3) holds between λ and the relationship shown in Equation (4) holds among Reynolds number Re, gas flow velocity U, representative length χ, and gas kinematic viscosity coefficient ν. It is requested from.
[0055]
[Expression 2]
Nu = 0.535 × Pr ^0.4 × Re ^0.5 (2)
[Equation 3]
Nu = (α × χ) / λ (3)
[Expression 4]
Re = (U × χ) / ν (4)
[0056]
Reaching the idea that the present inventors improve the combustion efficiency of flame retardant components in exhaust gases such as PFCs by increasing the ejection speed of the combustion-supporting gas using the combustion-supporting gas at atmospheric pressure or higher. The reason for this is that the ability to heat the exhaust gas was found to be important by two factors: the formation of the flame 25 and the flow of a combustion-supporting gas such as oxygen.
[0057]
Further, the present inventors have determined that the formation of the flame 25 is determined by the supply amount of the fuel gas and the ratio of the combustion-supporting gas mixed in advance with the fuel gas, assuming the structure of the tip of the exhaust gas combustion nozzle 7. It has also been found that the combustion efficiency of the flame retardant component greatly changes when the flow of the reactive gas, that is, the flow rate and flow rate of the combustion-supporting gas is changed.
[0058]
Further, the present inventors have provided that the combustion-supporting gas is supplied to the flame 25 so that the angle Θ between the combustion-supporting gas blowing direction and the exhaust gas passage direction is 90 ° to 60 °. It has also been found that it is preferable to blow. By injecting a flame-supporting gas into the flame by this method, even a flame-retardant removal component that is chemically stable and difficult to burn can be easily decomposed.
[0059]
In the method of the present invention, next, the flame retardant component in the exhaust gas is further decomposed by introducing the atmosphere from the inner cylinder 3 in the combustion completion part A shown in FIG. By burning the flame retardant component in this way, the combustion of the flame retardant removal component is completed.
[0060]
The exhaust gas from which the components to be removed are removed by combustion decomposition is then cooled by introducing the atmosphere from the inner cylinder 3 in the cooling section B shown in FIG. Since the temperature of the exhaust gas thus cooled quickly decreases, it can be released into the atmosphere in a safe state.
[0061]
In the method of the present invention, it is preferable to switch and supply different combustion-supporting gases corresponding to the decomposition characteristics of the removed components in the exhaust gas, for example, using the control means. According to this method, various flame-retardant exhaust gas components can be processed with one exhaust gas processing apparatus.
[0062]
The exhaust gas targeted by the exhaust gas treatment apparatus and the exhaust gas treatment method of the present invention must be removed or reduced in concentration when discharged into the atmosphere from the viewpoint of environmental protection, including flammable components and toxic components. An exhaust gas containing components and the like. Specifically, SiH discharged in various processes when manufacturing semiconductors _Four , SiH ₂ Cl ₂ , GeH _Four , B ₂ H ₆ , AsH _Three , PH _Three , NF _Three Or C ₂ F ₆ Etc., and particularly effective for the PFCs.
[0063]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
[0064]
Example 1
Exhaust gas treatment apparatus having an inner cylinder having the shape shown in FIG. ₁ = 78.5cm ² , Exhaust opening area of combustion cylinder: A ₂ = 78.5cm ² , A ₁ / A ₂ = 1), NF 31 liters / minute as exhaust gas diluted with nitrogen (changed in the range of 20 to 300 liters / minute) was supplied to the combustion nozzle, and city gas 13A as fuel gas was 16 liters / minute Is supplied to the combustion nozzle at 1.5x10 as a combustion-supporting gas ^Five Compressed air of Pa was supplied at an introduction angle Θ = 75 ° to combust and decompose NF3, and the residual ratio of NF3 after combustion was measured. The measurement results are shown in FIG.
[0065]
Comparative Example 1
The residual ratio of NF3 was measured in the same manner as in Example 1 except that the exhaust gas treatment apparatus of the aspect shown in FIG. The measurement results are shown in FIG.
[0066]
Examples 2 and 3
Using the same exhaust gas treatment apparatus as in Example 1, C2F61 liters / minute diluted with nitrogen (changed in the range of 20 to 200 liters / minute) as exhaust gas was supplied to the combustion nozzle, and city gas was used as fuel gas 13A was supplied to the combustion nozzle at 16 liters / minute, and in the case of Example 2, 1.5 × 10 6 was used as a combustion-supporting gas. ^Five Pa oxygen was supplied at an introduction angle Θ = 75 °, and in the case of Example 3, 1.5 × 10 5 was supplied. ^Five Compressed air of Pa was supplied at an introduction angle Θ = 75 ° to burn and decompose C2F6, and the C2F6 decomposition rate after combustion was measured. The measurement results are shown in FIG.
[0067]
Comparative Example 2
The decomposition rate was measured in the same manner as in Example 2 except that the exhaust gas treatment apparatus of the aspect shown in FIG. The measurement results are shown in FIG.
[0068]
Examples 4 and 5
Using the same exhaust gas treatment apparatus as in Example 1, CF41 liter / min as exhaust gas diluted with nitrogen (changed in the range of 20-50 liter / min) was supplied to the combustion nozzle, and city gas was used as fuel gas 13A was supplied to the combustion nozzle at 16 liters / minute, and in the case of Example 4, 1.5 × 10 6 was used as the combustion-supporting gas. ^Five Pa oxygen was supplied at an introduction angle Θ = 75 °, and in the case of Example 5, 1.5 × 10 5 was supplied. ^Five Compressed air of Pa was supplied at an introduction angle Θ = 75 ° to burn and decompose CF4, and the decomposition rate of CF4 after combustion was measured. The measurement results are shown in FIG.
[0069]
Comparative Example 3
The decomposition rate of CF4 was measured in the same manner as in Example 4 except that the exhaust gas treatment apparatus of the aspect shown in FIG. The measurement results are shown in FIG.
[0070]
Example 6
Using the apparatus shown in FIG. 1, NF 31 liter / min diluted with 300 liter / min nitrogen is supplied to the combustion nozzle as exhaust gas, and the fuel gas has an air ratio of 0.7 with respect to propane 10 liter / min. Is supplied to the combustion nozzle, compressed air is supplied as a combustion-supporting gas at 50 liters / minute, and the supply pressure is 1.5 × 10. ^Five The pressure was supplied at Pa, and the introduction angle Θ was changed in the range of 90 ° to 40 °, and the relationship between the introduction angle Θ and the decomposition rate of NF3 was measured. The results are shown in FIG.
[0071]
From FIG. 4, when the flame-retardant component in the exhaust gas is NF3, even if the supply amount of the fuel gas is the same, if the atmosphere is used as the combustion-supporting gas, the flow rate of diluted nitrogen is 100 liters / minute. Whereas the exhaust concentration reaches TLV-TWA, when compressed air is used as the combustion-supporting gas, the combustion efficiency is improved, and when the flow rate of diluted nitrogen is 200 liters / minute, the exhaust concentration of NF3 may reach TLV-TWA. I understand.
In addition, TLV-TWA (Threshold Limit Value-Time Weighed Average) means that the majority of workers are adversely affected by health even if they are repeatedly exposed every day under conditions of working hours of 8 hours every day and 40 hours every week. There is no acceptable concentration.
[0072]
FIG. 5 shows that the decomposition efficiency of C2F6 is far superior when compressed air or compressed oxygen is used as the combustion-supporting gas as compared with the case where the atmosphere is used as the combustion-supporting gas.
[0073]
FIG. 5 shows that when compressed oxygen is used as the combustion-supporting gas, even CF4 that is chemically stable and difficult to decompose can be decomposed among PFCs.
[0074]
FIG. 5 also shows that it is necessary to select a combustion-supporting gas corresponding to the flame-retardant component in the exhaust gas. Therefore, if the exhaust gas treatment apparatus of the present invention is used, it is possible to easily select a combustion-supporting gas corresponding to the flame retardant component to be subjected to the combustion decomposition treatment. It can also be seen that the ingredients can be processed.
[0075]
FIG. 6 shows that the combustion decomposition efficiency of the flame-retardant component is excellent when the introduction angle Θ of the combustion-supporting gas is 90 ° to 60 °.
[0076]
【The invention's effect】
As described above, the combustion exhaust gas treatment apparatus of the present invention has an outer cylinder and a combustion cylinder composed of an inner cylinder, and an exhaust gas combustion nozzle is provided at the bottom of the inner cylinder of the combustion cylinder. Is provided with means for supplying a combustion-supporting gas having a pressure equal to or higher than atmospheric pressure into the inner cylinder, so that PFCs that are chemically stable and difficult to burn can be easily decomposed.
[0077]
In the present invention, when compressed air, compressed oxygen-enriched air, or compressed oxygen is used as a combustion-supporting gas having a pressure equal to or higher than atmospheric pressure, even flame-retardant components such as PFCs can be combusted and decomposed. . In particular, when compressed oxygen having a pressure equal to or higher than atmospheric pressure is used as the combustion-supporting gas, CF4 that is particularly difficult to decompose among PFCs can be decomposed.
[0078]
In the combustion-type exhaust gas treatment apparatus of the present invention, a flame formed at the opening of the fuel gas supply passage so that the angle Θ between the combustion-supporting gas blowing direction and the exhaust gas passage direction is 90 ° to 60 °. In response to the gas Combustion gas injection If the means is provided in the inner cylinder, even PFCs that are chemically stable and difficult to burn can be more easily decomposed.
[0079]
In the combustion-type exhaust gas treatment apparatus of the present invention, when adopting a configuration in which the combustion-supporting gas is blown by means for providing the introduction pipe or the introduction nozzle in the inner cylinder, the combustion-supporting gas blowing direction and the exhaust gas passage direction are The combustion-supporting gas can be easily blown so that the angle Θ is 90 ° to 60 °.
[0080]
When the combustion type exhaust gas treatment apparatus of the present invention is provided with a control mechanism that switches and supplies the combustion-supporting gas according to the removed component in the exhaust gas, the decomposition characteristics of the flame-retardant component to be subjected to the combustion decomposition treatment are improved. Since the corresponding combustion-supporting gas can be switched and introduced, a plurality of flame-retardant components can be easily treated with one exhaust gas treatment device.
[0081]
In the combustion exhaust gas treatment method of the present invention, exhaust gas is supplied from an exhaust gas passage into the inner cylinder at the bottom of the inner cylinder of the combustion cylinder having an outer cylinder and an inner cylinder, and the fuel gas is discharged from the fuel gas supply path. Combustion of a flame by supplying a gas that surrounds the passage, forming a flame so as to surround the exhaust gas passage at the opening of the fuel gas supply passage, and blowing a flame-supporting gas having a pressure higher than atmospheric pressure into the flame After the flame retardant removal component in the exhaust gas is burned and decomposed, the atmosphere is then introduced to complete the decomposition of the flame retardant removal component in the exhaust gas, and then the atmosphere is introduced and the exhaust gas is cooled The exhaust gas is released into the atmosphere. Therefore, according to the method of the present invention, even PFCs that are chemically stable and difficult to burn can be easily decomposed.
[0082]
In the combustion-type exhaust gas treatment method of the present invention, when compressed air, compressed oxygen-enriched air, or compressed oxygen is used as the combustion-supporting gas having a pressure equal to or higher than atmospheric pressure, it is difficult to be chemically stable and difficult to burn. PFCs can be easily decomposed. In particular, when compressed oxygen having a pressure equal to or higher than atmospheric pressure is used as the combustion-supporting gas, CF4 that is particularly difficult to decompose among PFCs can be decomposed.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example of a combustion exhaust gas treatment apparatus of the present invention.
FIG. 2 is a longitudinal sectional view showing an example of the vicinity of a combustion nozzle according to the present invention.
FIG. 3 is a partially enlarged perspective view showing an example of a combustion state of fuel gas at the opening of the exhaust gas combustion nozzle of the present invention.
FIG. 4 is a graph showing the relationship between the residual ratio of NF3 and the combustion-supporting gas.
FIG. 5 is a graph showing the relationship between the decomposition rate of C2F6 and CF4 and the combustion-supporting gas.
FIG. 6 is a graph showing the relationship between the introduction angle Θ and the decomposition ratio of NF3.
FIG. 7 is a longitudinal sectional view showing an example of a conventional combustion exhaust gas treatment device.
FIG. 8 is a longitudinal sectional view showing another example of a conventional combustion type exhaust gas treatment apparatus.
FIG. 9 is a graph showing the relationship between temperature and decomposition performance for CF4, C2F6, and SF6.
FIG. 10 is a graph showing the relationship between diluted nitrogen amount and decomposition performance for CF4, C2F6, SF6, NF3, and CHF3.
[Explanation of symbols]
1 Exhaust gas treatment equipment
2 outer cylinder
3 inner cylinder
4 Combustion cylinder
7 Combustion nozzle
9 Conduit
10 Introduction pipe
11 Switching valve
12 Control mechanism operation panel
13 Electrical wiring connecting the switching valve 11 and the operation panel 12
21 Exhaust gas flow path
22 Fuel gas supply path
23 Fuel gas supply port
25 flame

Claims (2)

A combustion cylinder composed of an outer cylinder and an inner cylinder provided with air introduction means;
A combustion type exhaust gas treatment apparatus provided with an exhaust gas combustion nozzle provided at a bottom portion in the inner cylinder and having an exhaust gas passage and a fuel gas supply passage arranged concentrically around the exhaust passage,
Combustion-supporting gas blowing means comprising an introduction pipe or introduction nozzle for blowing a combustion-supporting gas having a pressure equal to or higher than the atmospheric pressure with respect to the flame formed at the opening of the fuel gas supply path, and removal components in the exhaust gas And a control mechanism for switching and supplying the combustion-supporting gas according to
In addition, the introduction pipe or the introduction nozzle is provided in the inner cylinder so that an angle Θ between the direction of blowing the combustion-supporting gas and the direction of the exhaust gas flow path is 90 ° to 60 °. Combustion type exhaust gas treatment equipment. The combustion exhaust gas treatment apparatus according to claim 1, wherein the combustion-supporting gas having a pressure equal to or higher than atmospheric pressure is compressed air, compressed oxygen-enriched air, or compressed oxygen.

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