Thermal detoxification device and thermal detoxification method using said device

Abstract

To provide a heat type detoxification device capable of achieving effective detoxification by an electric heater alone.SOLUTION: A heat type detoxification device 1 including a cylindrical chamber 2 and a heater part 3 fit on the inner peripheral surface 2a of the chamber 2 can directly pass and heat gas to be treated upward in the vertical direction in the inside of the heater part 3 to perform detoxification. The heater part 3 obtained by forming a planar or linear electric heater spiral in a plane view includes: a gas passage 6 consisting of an interval between the adjacent electric heaters and spiral in the plane view; and a rectification part 7 covering the upper part of the heater part 3. The rectification part 7 fit on the inner peripheral surface 2a of the chamber 2 has an exhaust hole 7a allowing the passage of treated gas in the central part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a thermal abatement device and a thermal abatement method for safely discharging gases used in the manufacturing process of electronic products such as semiconductors. [Background technology]

[0002] Conventionally, there have been various methods for abating gases emitted from electronics manufacturing plants. For example, thermal abatement treatment is applied to gases whose harmful or hazardous substances can be removed by thermal decomposition, such as TMA (trimethylaluminum) used in thin film formation technologies such as ALD (Atomic Layer Deposition).

[0003] The mainstream thermal detoxification equipment is of the combustion type using a gas burner. While this type of thermal detoxification equipment has the advantage of being able to efficiently heat the gas to be treated to the temperature required for detoxification, it has the disadvantage of requiring relatively large amounts of extra utilities such as gas cylinders and combustion chambers, as well as safety concerns.

[0004] Therefore, in order to perform decontamination treatment safely while making the device itself compact, thermal decontamination devices have been developed that can thermally decompose the gas to be treated by heating it with an electric heater.For example, the thermal decontamination device shown in Patent Document 1 below is known.

[0005] However, in the thermal detoxification device of Patent Document 1 below, it is difficult to create the desired high-temperature atmosphere by heating using an electric heater alone, so a thermal detoxification device has been developed that creates the desired high-temperature atmosphere by igniting fuel gas with an electric heater, as shown in Patent Document 2 below (paragraph 0009 of Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 3016690 [Patent Document 2] Patent No. 3866412 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, the reality with thermal detoxification devices is that even if an electric heater is used to resolve the concerns about the large size and safety that arise with combustion-type devices, the electric heater alone cannot provide the heating required for thermal detoxification, and ultimately heating by combustion is used.

[0008] Therefore, there is a strong demand for a device that can effectively perform detoxification treatment using only heating by an electric heater without involving combustion, that is, a thermal detoxification device that can be made compact and does not require consideration of the dangers of combustion. [Means for solving the problem]

[0009] The present invention provides a thermal detoxification device that realizes effective detoxification treatment using an electric heater alone by utilizing a heater structure characterized by the arrangement of an electric heater and a gas flow path, and a thermal detoxification method using said device.

[0010] In brief, the thermal detoxification device of the present invention is a thermal detoxification device comprising a cylindrical chamber and a heater section which fits into the inner circumferential surface of the chamber, and which heats and detoxifies the gas to be treated by passing it directly through the heater section in an upward, vertical direction, and which is formed by forming a planar or linear electric heater into a spiral shape in a planar view, and which has a gas flow passage which is spiral in a planar view formed by the spacing between adjacent electric heaters, and which is provided with a straightening section which covers the upper part of the heater section, and which is configured to fit into the inner circumferential surface of the chamber and have a discharge hole in the center which allows the treated gas to pass through.

[0011] Therefore, the gas to be treated can be effectively heated to a temperature required for pyrolysis by the electric heaters arranged in close proximity in a direction perpendicular to the gas flow direction (up and down direction), and no heating means other than the electric heater is required. In addition, the powder produced as a by-product of pyrolysis can be trapped in the gas flow path, and cleaning equipment such as a scrubber is not required.

[0012] Preferably, the planar electric heater has a large number of gas passage holes penetrating the surface, which allows heating and trapping of by-product powder to be performed more efficiently.

[0013] Furthermore, by providing a pressure sensor upstream of the heater section, it is possible to monitor whether or not the heater section is clogged with powder or the like produced as a by-product by thermal decomposition.

[0014] Preferably, a preheater section is provided upstream of the starting point of the gas flow passage in the heater section, and the preheater section is composed of a truncated inverted cone-shaped reflector covering the lower end of the heater section, thereby making it possible to effectively utilize the thermal energy of the heater section for preheating, and effectively suppressing thermal decomposition and the generation of powder by-products.

[0015] More preferably, by disposing a net made of a metal that functions as a catalyst in the detoxification treatment at the lower end opening of the reflector, it is possible to promote even more efficient detoxification treatment.

[0016] The thermal detoxification method of the present invention is a thermal detoxification method using the thermal detoxification device of the present invention described above, in which the gas to be treated is directly passed upward in the vertical direction through the gas flow passage of the heater section and heated, thereby pyrolyzing the gas to be treated and trapping the powder produced as a by-product by the pyrolysis, thereby enabling safe and clean detoxification treatment. Effect of the Invention

[0017] The thermal detoxification device of the present invention has an arrangement structure in which electric heaters are closely spaced in a direction perpendicular to the gas flow direction, which allows the gas to be treated to be efficiently heated while also providing a gas flow path structure that can trap by-product powder, making it possible to perform thermal detoxification using only the electric heaters and contributing to the miniaturization and safety of the device.

[0018] In addition, the thermal detoxification method according to the present invention can perform pyrolysis treatment using only a heater unit consisting of an electric heater without combustion, enabling safe detoxification treatment. In addition, clean detoxification treatment can be performed without using a cleaning device such as a scrubber. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram of a thermal detoxification device using a planar electric heater according to the present invention. [Diagram 2] 1A to 1C are diagrams illustrating a heater unit composed of a planar electric heater, in which (A) is a plan view of the heater unit, (B) is a side view of the heater unit, and (C) is a perspective view of the heater unit. [Diagram 3] FIG. 1 is a schematic diagram of a thermal detoxification device using a linear electric heater according to the present invention. [Figure 4] 1A to 1C are diagrams illustrating a heater section configured with a linear electric heater, in which (A) is a plan view of the heater section, (B) is a side view of the heater section, and (C) is a perspective view of the heater section. [Diagram 5] FIG. 2 is a side view showing an example of a heater unit in which a plurality of linear electric heaters are combined. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The best embodiment of the thermal abatement device and the thermal abatement method using the device according to the present invention will be described with reference to Figures 1 to 5. Note that in each figure, the power sources and electric wires related to the electric heaters 4 and 5 are omitted.

[0021] <Basic configuration of thermal abatement equipment> As shown in Figures 1 and 3, the thermal detoxification device 1 of the present invention has a basic configuration including a cylindrical chamber 2 and a cylindrical or conical heater section 3 that fits into the inner surface 2a of the chamber 2, and the gas to be treated can be passed directly upward through the inside of the heater section 3 to be heated and detoxified.

[0022] Therefore, a gas inlet 2b is provided at the lower end of the chamber 2 and a gas outlet 2c is provided at the upper end thereof, and the heater section 3 is fitted into the inner surface 2a of the cylindrical chamber 2. By doing so, the target gas introduced into the chamber 2 through the gas inlet 2b will not be discharged from the gas outlet 2c without passing through the heater section 3.

[0023] The chamber 2 is made of metals that do not affect the thermal decontamination process, such as stainless steel (SUS: Steel Use Stainless), heat resistant steel (SUH: Steel Use Heat Resisting), Inconel (registered trademark), Hastelloy (registered trademark), etc., and not only can the internal volume be adjusted as appropriate, but the volume of the heater section 3 relative to the internal volume of the chamber 2 can also be adjusted as appropriate. As described below, it is preferable to use an electric heater of the resistance heating type for the heater section 3, and it is desirable to interpose an insulating sheet between the inner peripheral surface 2a of the chamber 2 and the outer peripheral surface 3a of the heater section 3 to prevent problems due to short circuits, leakage current, etc.

[0024] 1 and 3, P is a pipe for transporting the gas to be treated and the treated gas, and C is a cooler for cooling the treated gas. The gas to be treated, transported from a semiconductor factory or the like through the pipe P to the thermal detoxification device 1, is detoxified by the thermal detoxification device 1 to become treated gas, which is cooled in the cooler and then transported through the pipe P to be released into the atmosphere or the like.

[0025] <Heater section configuration> The heater section 3 is formed by winding a planar electric heater 4 into a spiral shape in plan view and forming it into a cylindrical shape as shown in Figures 1 and 2, or by forming a linear electric heater 5 into a spiral shape in plan view as shown in Figures 3 and 4. As the electric heater, a known electric heater can be used, but in order to form a high-temperature atmosphere required for thermal decomposition of a target gas at, for example, 600°C or higher, or even 1000°C or higher, and in addition to forming it into a spiral shape in plan view, it is preferable to use an electric heater of a resistance heating type, and in particular, it is preferable to use an electric heater that uses a metal such as nichrome or Kanthal (registered trademark) as a heating resistor.

[0026] When a planar electric heater 4 is used, as shown in Figures 1 and 2, it is formed so that it has a spiral shape in plan view and a cylindrical overall shape, and the interval between adjacent planar electric heaters 4, i.e., the interval between adjacent spirals in plan view, is made as narrow as possible and the adjacent interval is used as a gas passage 6. Therefore, the heater part 3 is formed by winding the planar electric heaters 4 in a spiral shape while bringing them as close as possible to each other, and a gas passage 6 that is as narrow as possible is formed.

[0027] In this way, by arranging the planar electric heaters 4 closely in the direction perpendicular to the gas flow direction (upward in the vertical direction), the gas flow passage 6 is structured to efficiently heat the gas to be treated and trap by-product powder. Note that in the present invention, as long as the gas flow passage 6 can be provided, the planar electric heaters 4 may partially contact each other.

[0028] In addition, although not specifically shown, it is desirable for the planar electric heater 4 to have a large number of gas passage holes passing through it. This is because it allows for more efficient heating and makes it possible to trap powder produced as a by-product by pyrolysis. In addition, it is optional to roughen the surface of the planar electric heater 4 to make it easier to collect the by-product powder, depending on the implementation.

[0029] Alternatively, when a linear heater 5 is used, it is formed so that it is spirally formed in a plan view and has a conical overall shape, as shown in Figures 3 and 4, and the adjacent space between the linear electric heaters 5, i.e., the adjacent space between the spirals in a plan view, is made as narrow as possible and the adjacent space is used as a gas flow path 6.

[0030] Therefore, when the linear electric heater 5 is used, similarly to the planar electric heater 4, the linear electric heaters 5 are arranged closely to each other in the direction perpendicular to the gas flow direction, so that the gas flow passage 6 can efficiently heat the gas to be treated and trap the by-product powder. In the present invention, as long as the gas flow passage 6 can be provided, the linear heaters 5 may partially contact each other. In addition, the surface of the linear heater 5 may be roughened to make it easier to collect the by-product powder, depending on the implementation.

[0031] Furthermore, when a linear electric heater 5 is used, a plurality of linear electric heaters 5 formed into a spiral shape in plan view can be stacked to form the heater section 3 as shown in Fig. 5, thereby realizing more efficient heating and trapping of by-product powder. Note that, although the overall shape of the linear electric heater 5 formed into a spiral shape in plan view is shown as a cone in this embodiment, in the present invention, it is also possible to arbitrarily form it into a truncated cone shape, an inverted cone shape, or a truncated inverted cone shape depending on the implementation.

[0032] In the present invention, the gas flow passage 6 in the heater section 3 has a lower end portion 6a as a starting point and an upper end portion 6b as a terminal point, regardless of whether the gas flow passage 6 is configured with the planar electric heater 4 or the linear electric heater 5. This is because, as described above, the gas to be treated is introduced from the gas inlet 2b at the lower end of the chamber 2 and the gas to be treated comes into contact with the heater section 3 from below. In addition, the gas to be treated is heated and expands, and moves from the bottom to the top in the gas flow passage 6.

[0033] In addition, in the present invention, as described above, the planar electric heaters 4 or the linear electric heaters 5 are arranged closely together in the direction perpendicular to the gas flow direction, thereby making the gas flow passage 6 of the heater section 3 as narrow as possible, thereby achieving both highly efficient heating and trapping of by-product powder.

[0034] Therefore, there is a risk that the trapped by-product powder will clog the gas flow passage 6, but in the present invention, a pressure sensor is provided upstream of the heater section 3 to monitor whether the heater section 3 is clogged. Although not specifically shown, the pressure sensor may be located anywhere in the chamber 2, either inside or outside, as long as it is located upstream of the heater section 3.

[0035] Needless to say, the heater section 3 is provided with a circuit for detecting problems such as short circuits and leakage current caused by placing the sheet electric heaters 4 or the line electric heaters 5 closely adjacent to each other.

[0036] <Configuration of rectifier> 1 and 3, the present invention is configured such that a rectifier 7 is provided so as to cover the upper part of the heater part 3. The rectifier 7, like the chamber 2, is made of a metal that does not affect the thermal detoxification treatment, such as stainless steel, heat-resistant steel, Inconnel (registered trademark), or Hastelloy (registered trademark).

[0037] The straightening section 7 has an exhaust hole 7a in the center that allows the treated gas to pass through, and is arranged to encourage the gas to pass through the center (the part along the central axis) of the heater section 3, which is the part with the least loss of thermal energy in the heater section 3, i.e., the part with the highest temperature.

[0038] 1 and 3, the gas to be treated flowing in the gas flow passage 6 of the heater section 3 is guided to the center of the heater section 3 by the flow straightener section 7 as indicated by the arrows in the figures, and after the thermal decomposition process, the treated gas is discharged from the exhaust hole 7a. Therefore, the electric heaters 4 and 5 alone can effectively heat the gas to a temperature required for thermal decomposition and perform the detoxification process.

[0039] It is preferable that the flow straightening section 7 is shaped to match the shape of the upper part of the heater section 3. When the heater section 3 is cylindrical as shown in FIG. 1, the flow straightening section 7 is made disk-shaped. When the heater section 3 is conical as shown in FIG. 3, the flow straightening section 7 is made conical-tube-shaped to effectively cover the upper part of the heater section 3 and promote efficient passage of the gas to be treated to the heater section 3.

[0040] <Preheater section configuration> In the present invention, as shown in Figures 1 and 3, a preheater section 8 is preferably provided upstream of the starting point 6a of the gas flow passage 6 in the heater section 3. The preheater section 8 makes it possible to effectively utilize the thermal energy leaked from the heater section 3 for preheating, thereby enabling effective thermal decomposition and suppression of powder by-production.

[0041] The preheater section 8 is made of a reflector 9 in the shape of a truncated inverted cone that covers the lower end of the heater section 3, and by covering the lower end of the heater section 3 with the upper opening 9b of the reflector 9, it is possible to collect and effectively utilize the heat energy leaking from the heater section 3 by reflection. The reflector 9 is made of a metal such as stainless steel that has good heat reflectivity and does not affect the thermal abatement treatment.

[0042] More preferably, a more efficient abatement process can be promoted by disposing a net 10 made of a metal that functions as a catalyst in the abatement process at the lower end opening 9a of the deflector 9. Examples of metals that function as catalysts include platinum for hydrocarbon gases and nickel for ammonia gas.

[0043] <Thermal abatement method> The thermal abatement method according to the present invention is a thermal abatement method using the thermal abatement device 1 according to the present invention described above, and has the following characteristics.

[0044] That is, by directly passing the gas to be treated upward through the gas flow passage 6 consisting of closely spaced electric heaters 4, 5 arranged perpendicular to the gas flow direction, the gas to be treated is heated, and the gas to be treated is pyrolyzed while the powder produced as a by-product by the pyrolysis is trapped.

[0045] Therefore, the pyrolysis treatment can be performed only by the heater unit 3 consisting of the planar electric heater 4 or the linear electric heater 5 without combustion, and safe detoxification treatment is possible. In addition, clean detoxification treatment is possible without using a cleaning device such as a scrubber. [Explanation of symbols]

[0046] Reference Signs List 1...thermal abatement device, 2...chamber, 2a...inner surface, 2b...gas inlet, 2c...gas outlet, 3...heater section, 3a...outer surface, 4...planar electric heater, 5...linear electric heater, 6...gas flow path, 6a...starting point, 6b...ending point, 7...straightening section, 7a...discharge hole, 8...preheater section, 9...reflector, 9a...lower end opening, 9b...upper end opening, 10...net, C...cooler, P...pipe.

Claims

1. A thermal detoxification device comprising a cylindrical chamber and a heater section that fits into the inner circumferential surface of the chamber, and which heats and detoxifies a gas to be treated by passing the gas directly through the heater section in an upward, vertical direction, wherein the heater section is formed by forming a planar or linear electric heater into a spiral shape in a planar view, and has a gas flow passage that is spiral in a planar view formed by the spacing between adjacent electric heaters, and is provided with a straightening section that covers the upper part of the heater section, and the straightening section fits into the inner circumferential surface of the chamber and has an exhaust hole in the center to allow the treated gas to pass through.

2. 2. The thermal abatement device according to claim 1, wherein the planar electric heater has a large number of gas passage holes passing therethrough.

3. 3. The thermal abatement device according to claim 1, further comprising a pressure sensor provided upstream of the heater section.

4. A thermal decontamination device as described in any one of claims 1 to 3, characterized in that a preheater section is provided upstream of the starting point of the gas flow path in the heater section, and the preheater section consists of a truncated inverted cone-shaped reflector covering the lower end of the heater section.

5. 5. The thermal abatement device according to claim 4, further comprising a net made of a metal that functions as a catalyst in the abatement process, disposed at a lower end opening of said reflector.

6. A thermal detoxification method using a thermal detoxification device described in any one of claims 1 to 5, characterized in that the gas to be treated is directly passed upward in the vertical direction through the gas flow passage of the heater section to heat the gas, thereby thermally decomposing the gas to be treated and trapping powder produced as a by-product by the thermal decomposition.

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