JP3267592B2 - Combined gas treatment system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined gas treatment system for purifying gaseous effluents generated from a chemical factory or the like before releasing them to the atmosphere, and more particularly to a composite gas treatment system generated in a semiconductor manufacturing process. The present invention relates to a composite gas treatment system configured to burn toxic gas emissions with a raw material obtained by electrolysis, remove fine particles, and discharge the particulates to the outside.

[0002]

2. Description of the Related Art Diffusion, chemical vapor deposition (chemica)
Semiconductor manufacturing processes such as vapor deposition and etching generate a large amount of gas emissions. Such gas emissions are highly toxic, explosive and corrosive and must be properly cleaned before being released to the atmosphere.

[0003] In general, gas emissions are SiH ₄ , Cl ₂ , N
It is composed of components such as H ₃ , AsH ₃ , PH ₃ , B ₂ H ₆ and GeH ₄ and contains fine particles such as silica particles. Therefore, in order to prevent environmental pollution due to gas emission, it is necessary to reduce the concentration of harmful components in the gas emission to an allowable level.

Heretofore, wet scrubbers, combustion scrubbers, wet / combustion scrubbers, adsorption scrubbers, and catalytic scrubbers have been widely used for the purpose of purifying gas emissions and reducing the concentration of harmful components.

As disclosed in US Pat. No. 5,011,520, issued Apr. 30, 1991, wet scrubbers convert scrubbed water into scrubbery water containing particulates.
This device separates and removes harmful components by injecting bbing liquid). This wet scrubber has a large processing capacity,
There is an advantage that the operating cost is low and the halogen gas can be processed, but the processing efficiency is low and the gas inlet may be blocked during long-time operation.

[0006] Combustion scrubbers burn gas emissions with a heater to decompose and oxidize.
n) can efficiently treat combustible gas emissions, but has the drawback that by-products are difficult to handle and halogen gas cannot be burned.

On the other hand, the mixed scrubber can efficiently treat most of the mixed gas including the halogen gas at a relatively low operation cost.

However, the conventional mixed scrubber has the following problems. First, a plurality of combustors operating at different temperatures must be manufactured and installed, depending on the type of gas emission to be burned. Therefore, the production cost is high and a large installation space is required. In addition, the heaters used in the conventional mixed scrubbers have a "heat fade (heat f
ade) Not only is the phenomenon likely to occur and performance degraded,
Since there is a limit to the rise in combustion temperature, it is difficult to completely burn high-temperature combustible gas emissions. As a countermeasure against this, it is conceivable to raise the combustion temperature by introducing external fuel into the heater and burning it. However, in this case, the piping for supplying the fuel becomes complicated, and the fuel leaks. There is a danger of explosion due to

[0009]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to separately introduce a low-temperature combustible gas emission and a high-temperature combustible gas emission and burn them at different temperatures. It is an object of the present invention to provide a composite gas processing system having a compact structure capable of performing the above.

It is another object of the present invention to simplify the fuel supply line by burning the hot combustible gas emissions using the fuel produced in the apparatus and to reduce the risk of an explosion accident due to fuel leakage. It is to provide a combined gas treatment system.

[0011]

SUMMARY OF THE INVENTION A composite gas treatment system according to the present invention is a system for purifying low-temperature combustible gas emissions and high-temperature combustible gas emissions generated in a chemical process and releasing the same into the atmosphere. A free-standing housing having a chamber and a lower chamber, a low-temperature combustor provided in the upper chamber of the housing, for introducing a low-temperature combustible gas emission, pyrolyzing at a first temperature, and then discharging the gas to the outside; After the high-temperature combustible gas exhaust gas is introduced in the upper chamber and is thermally decomposed at a second temperature higher than the first temperature,
A high temperature combustor to be discharged to the outside and a fuel gas generating unit disposed in a lower chamber of the housing to generate fuel gas and supply the fuel gas to the high temperature combustor are provided.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First, as shown in FIG. 1, the composite gas processing system according to the present embodiment includes a stand-alone housing 10 having an upper chamber 12 and a lower chamber 14. A caster 16 is attached to the bottom surface of the housing 10, so that the gas processing system of the present embodiment can be easily moved. In the upper chamber 12 of the housing 10, a low-temperature combustor 18 for vertically introducing and burning low-temperature combustible gas emissions generated in a chemical process, for example, a semiconductor manufacturing process is provided upright. Examples of low-temperature combustible gas emissions include SiH ₄ , SiH ₂ Cl ₂ , N
_{H 6, WF 6, PH 3} , B 2 is H ₆ and the like, but is not limited thereto.

As shown in FIG. 2, the low-temperature combustor 18 has a substantially cylindrical casing 20 in which a refrigerant passage is formed. This casing 20 has a central combustion chamber 20a, an upper inlet end 20b and a lower outlet end 20c. Inside the casing 20, a cylindrical heater element 22 for converting electric energy into heat energy is provided.
0 is installed coaxially in the longitudinal direction. A heat insulating material 24 is provided on the outer periphery of the heater element 22 to suppress heat from radiating to the outside. On the other hand, a liner 26 having excellent heat resistance and corrosion resistance is provided on the inner periphery thereof. The liner 26 is manufactured, for example, from a ceramic or a nickel alloy. Then, heat energy is absorbed from the heater element 22 and the incandescent state (glow stat) is obtained.
e), the central combustion chamber 2 of the casing 20
Thermal decomposition of the low temperature combustible gas emissions passing through
Oxidize. The heater element 22 is provided in the central combustion chamber 2.
0a is controlled to be maintained at about 750 ° C.

The above-described casing 20 of the low-temperature combustor 18
A dust collector 28 is provided at the outlet end 20c of the air conditioner. The dust collector 28 has a role of collecting and removing fine particles in the pyrolysis gas discharged from the low-temperature combustor 18, and the connecting pipe 32.
And a hopper 30 connected to the central combustion chamber 20a of the low-temperature combustor 18 via the hopper 30. The connecting pipe 32 has a blower 3
4 are connected via an air tube 36. The blower 34 blows air into the hopper 30 to generate a cyclone airflow, and causes fine particles mixed in the pyrolysis gas to fall downward. At the lower end of the hopper 30, a collection tank 38 for collecting falling particles is mounted, and the particles collected in the collection tank 38 are transferred to a temporary storage room 42 by a transfer mechanism 40. The fine particles in the temporary storage room 42 are carried out and removed.

At the upper end of the hopper 30, a low temperature side exhaust pipe 44 is provided.
Is provided. The lower end 44a of the low temperature side exhaust pipe 44 is
It extends into the hopper 30 for a long time. For this reason, it is possible to prevent fine particles in the pyrolysis gas that enters the hopper 30 through the connection pipe 32 from directly flowing into the low-temperature side exhaust pipe 44.
In the low temperature side exhaust pipe 44, a filter 46 for filtering the pyrolysis gas before releasing it to the outside is provided.

As shown in FIG. 1, a high-temperature combustor 48 is provided in the upper chamber 12 of the housing 10 in parallel with the low-temperature combustor 18. The high-temperature combustor 48 is suitable for introducing and burning high-temperature combustible gas emissions generated in a semiconductor manufacturing process or the like. Examples of hot combustible gas emissions include N
_{F 3, CF 4, C 2} F 6, SF 6, CHF 3, although C ₄ F ₈ include, but are not limited to.

As is clearly shown in FIG.
Is a substantially cylindrical casing 5 in which a refrigerant flow passage is formed.
0 is provided. This casing 50 is provided in the central combustion chamber 5.
0a, an upper inlet end 50b and a lower outlet end 50c. Inside the casing 50, a cylindrical heater element 52 for converting electric energy into heat energy is installed coaxially in the longitudinal direction of the casing 50.
A heat insulating material 54 is provided on the outer periphery of the heater element 52 to suppress heat from radiating to the outside. On the other hand, a liner 5 having excellent heat resistance and corrosion resistance
6 are provided. The liner 56 is made of, for example, a ceramic or a nickel alloy, and absorbs heat energy from the heater element 52 to become incandescent, raising the temperature of the central combustion chamber 50a to about 750 ° C.

At the upper end of the high temperature combustor 48, the central combustion chamber 5
A fuel injection nozzle 58 for injecting fuel downward in 0a is provided. As shown in FIGS. 1 and 5, the fuel injection nozzle 58 is connected to the lower chamber 14 of the housing 10.
Oxygen and hydrogen gas are supplied from a fuel gas generating unit 60 installed in the fuel cell through a fuel supply pipe 62. The hydrogen gas injected from the fuel injection nozzle 58 spontaneously ignites and burns at about 580 ° C., and the internal temperature of the central combustion chamber 50 a of the high-temperature combustor 48 becomes about 1200 due to the combustion of the hydrogen gas.
° C to efficiently pyrolyze or oxidize hot combustible gas emissions. In the embodiment shown in FIG. 1, compressed air from an air compressor 64 connected to a fuel injection nozzle 58 is also supplied into the central combustion chamber 50a by the nozzle 58.

The casing 50 of the high-temperature combustor 48 described above.
The lower outlet end 50c is provided with a wet scrubber 66 for cooling and neutralizing the pyrolysis gas and removing water-soluble substances and fine particles contained therein. As shown in FIG. 3, the wet scrubber 66 includes a scrubbing vessel 68 in which the pyrolysis gas contacts water, a water tank 70 for storing water flowing out of the scrubbing vessel 68 through the overflow tube 72, and a water tank 70.
And a water recirculation pipe 74 for sucking up water and injecting it into the scrubbing container 68. The water recirculation pipe 74 has a water injection nozzle 76 projecting into the scrubbing vessel 68. The water injection nozzle 76 is provided directly below the outlet end 50 c of the high-temperature combustor 48 in order to inject the water in the water storage tank 70 into the scrubbing container 68 by the Venturi effect. The scrubbing container 68 receives a supply of external water through a water supply pipe 78. The water in the water storage tank 70 is discharged to the outside through the drain pipe 80. Scrubbing container 68
And the water tank 70 is made of stainless steel with excellent corrosion resistance,
It is preferable to form a Teflon layer on the inner wall surface.

A neutralizing agent supply device 82 for neutralizing water and appropriately maintaining the hydrogen ion concentration (pH) is connected to the scrubbing container 68. This neutralizer supply device 8
Numeral 2 stores, for example, potassium hydroxide, and supplies an appropriate amount of potassium hydroxide into the scrubbing container 68 according to the output signal of the hydrogen ion concentration sensor 84 installed in the water tank 70. Bubble generators 86 are provided on the bottom surfaces of the scrubbing container 68 and the water storage tank 70, respectively. The bubble generator 86 receives compressed air from the air compressor 88 to generate a large amount of bubbles, thereby preventing precipitation of fine particles and improving scrubbing efficiency of the pyrolysis gas.

A high-temperature side exhaust pipe 90 for discharging the purified gas to the outside is arranged in parallel with the high-temperature combustor 48 above the scrubbing vessel 68. This high temperature side exhaust pipe 90
Is provided with a filter 92 for filtering moisture and fine particles in the exhaust gas. As shown in FIG.
0 is connected to the low-temperature side exhaust pipe 4 described above,
The exhaust gas that has flowed out through both exhaust pipes 44 and 90 is exhausted outside through one common exhaust duct 94.

As shown in FIGS. 1, 4 and 5, the fuel gas generating unit 60 for supplying the fuel gas to the fuel injection nozzle 58 includes an electrolyzing device 96 for electrolyzing water to generate oxygen and hydrogen gas. It has. This electrolyzer 96
Receives water from a water storage tank 98. This water storage tank 98 is connected to a feedback tank 102 via a water pump 100. Therefore, the water introduced into the feedback tank 102 from the water supply source 104 is pressure-fed to the water storage tank 98 by the water pump 100 and then supplied to the electrolyzer 96 again. In addition, the water pump 100 includes the feedback tank 1.
02 is also supplied to the flashback prevention tank 106, and water overflowing from the flashback prevention tank 106 is supplied to the feedback tank 1
Return to 02. Flashback prevention tank 1 filled with water
06 is such that the flame of the fuel injection nozzle 58 is discharged by introducing oxygen and hydrogen gas generated from the electrolyzer 96 into the lower inlet 106a and discharging the oxygen and hydrogen gas to the upper outlet 106b via water. It prevents propagation through the supply pipe 62 to the electrolyzer 96, thereby preventing an explosion accident.

As shown in FIG. 4, the electrolyzer 96 is composed of a plurality of plate electrodes 1 integrally laminated with bolts 110.
08, and each plate electrode 108 is electrically connected to a power supply (not shown). In such a plate electrode 108, a water inlet 108a and a gas outlet 108b are formed. The water introduction hole 108a communicates with the water storage tank 98 as shown in FIGS.
8b communicates with the flashback prevention tank 106. Since an insulating gasket 112 and a sealing ring 114 having a considerable thickness are sandwiched between the plate electrodes 108,
A space for introducing water required for electrolysis is formed between the plate electrodes 108. By the application of the current, the plate electrode 108 of the electrolyzer 96 electrolyzes the water therebetween to generate oxygen and hydrogen gas. The generated oxygen and hydrogen gas are supplied to the gas discharge holes 10 of the plate electrode 108.
The fuel is discharged through the flashback prevention tank 106 and supplied to the fuel injection nozzle 58 of the fuel combustor 48 of the high temperature combustor 48. According to the embodiment shown in FIG. 1, the fuel gas generating unit 60 has two electrolyzers 96, but the number of the electrolyzers 96 increases or decreases according to the amount of fuel gas required in the high-temperature combustor 48. Let it.

Next, the operation of the composite gas processing system according to the present invention will be described. First, low-temperature combustible gas emissions generated in a semiconductor manufacturing process or the like are introduced into the central combustion chamber 20 a of the low-temperature combustor 18. Next, it is decomposed by the heat of about 750 ° C. generated in the heater element 22. The pyrolysis gas is sent to the hopper 30 of the dust collector 28 via the connecting pipe 32. The blower 34 blows air into the hopper 30 to generate a cyclone airflow, and the fine particles mixed with the pyrolysis gas fall downward and are collected in the collection tank 38. The fine particles collected in the collection tank 38 are transferred to the transfer mechanism 4.
After being transferred to the temporary storage room 42 by 0, it is carried out and discarded.

The pyrolysis gas passing through the hopper 30 of the dust collector 28 ignites spontaneously when mixed with air from the blower 34. That is, the pyrolysis gas discharged from the low temperature combustor 18 is in a heated state, and when mixed with air, spontaneously ignites due to an oxidation reaction. Therefore, the pyrolysis gas is burned in the hopper 30 and pyrolyzed again, so that the processing efficiency is significantly improved. The pyrolysis gas discharged from the hopper 30 is discharged to the outside after passing through the filter 46 of the low temperature side exhaust pipe 44.

On the other hand, the high-temperature combustible gas exhaust gas is introduced into the central combustion chamber 50a of the high-temperature combustor 48. High temperature combustor 4
The eighth heater element 52 raises the temperature of the central combustion chamber 50a to about 750 ° C. The hydrogen gas injected from the fuel injection nozzle 58 spontaneously ignites at about 580 ° C. and burns. Then, the temperature of the central combustion chamber 50a of the high-temperature combustor 48 rises to about 1200 ° C., and the high-temperature combustible gas exhaust is efficiently thermally decomposed. Fuel gas, that is, oxygen and hydrogen gas, is generated by the electrolyzer 96 of the gas generating unit 60 and passes through the flashback prevention tank 106 to the fuel injection nozzle 5.
8.

The gas pyrolyzed in the central combustion chamber 50 a of the high temperature combustor 48 is introduced into a scrubbing vessel 68 of a wet scrubber 66. Water injection nozzle 7 of water circulation pipe 74
6 injects water into the scrubbing container 68 by the Venturi effect. The injected water is mixed with the pyrolysis gas to cool the pyrolysis gas and separate water-soluble substances and fine particles present in the pyrolysis gas from the pyrolysis gas. The water overflowing from the scrubbing container 68 is stored in a water storage tank 70.
Is returned to the scrubbing container 68 again through the water recirculation pipe 74. At this time, the hydrogen ion concentration sensor 84 detects the hydrogen ion concentration of the water, and when the hydrogen ion concentration exceeds a predetermined reference value, the neutralizing agent supply device 82 operates to activate the neutralizing agent such as potassium hydroxide. Water is neutralized by charging a neutralizing agent into the scrubbing container 68. Further, the air compressor 88 is provided with the bubble generators 8 provided in the scrubbing vessel 68 and the water tank 70, respectively.
The compressed air is supplied to 6 to generate bubbles. Due to the generation of the bubbles, the precipitation of the fine particles is prevented, and the scrubbing efficiency can be improved. The purified gas that has passed through the scrubbing container 68 of the wet scrubber 66 is discharged to the outside via the filter 92 of the high temperature side exhaust pipe 90.

[0029]

As described above in detail, according to the composite gas processing system of the present invention, low-temperature combustible gas emissions and high-temperature combustible gas emissions can be simultaneously burned in one apparatus. Further, by burning the high-temperature combustible gas emissions using the fuel generated in the device,
This has an excellent effect of simplifying the fuel supply line and preventing an explosion accident due to fuel leakage.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram showing a composite gas processing system according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing in detail a low-temperature combustor, a dust collector, and a low-temperature side exhaust pipe constituting the composite gas processing system shown in FIG.

FIG. 3 is a detailed partial cross-sectional view of a high-temperature combustor, a wet scrubber, and a high-temperature side exhaust pipe constituting the combined gas processing system shown in FIG. 1;

FIG. 4 is an exploded perspective view of an electrolyzer including a plurality of plate electrodes.

FIG. 5 is a schematic block diagram showing a fuel gas generation unit and a high temperature combustor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Housing 12 Upper chamber 14 Lower chamber 16 Caster 18 Low temperature combustor 20 Cylindrical casing 22 Heater element 24 Insulation material 26 Liner 28 Dust collector 30 Hopper 32 Connecting pipe 34 Blower 36 Air tube 38 Collection tank 40 Transfer mechanism 42 Temporary storage room 44 Low temperature side exhaust pipe 46 Filter 48 High temperature combustor 50 Cylindrical casing 52 Heater element 54 Insulation material 56 Liner 58 Fuel injection nozzle 60 Fuel gas generation unit 62 Fuel supply pipe 64 Air compressor 66 Wet scrubber 68 Scrubbing container 70 Water tank 80 Drainage pipe 82 Neutralizer supply device 84 Hydrogen ion concentration sensor 86 Bubble generator 88 Air compressor 90 High-temperature side exhaust pipe 92 Filter 94 Common exhaust duct 96 Electrolysis device 98 Water storage tank 100 Otaponpu 102 Feedback tank 106 back prevention tank 108 electrode 112 insulating gasket 114 sealing rings

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Bong Kyu Seo Korea Thunbok, Cheongwon-gun, Ochan-Mun Ghajwalli 347 (56) References JP-A-62-152517 (JP, A) JP-A Sho 63-62528 (JP, A) JP-A-9-14631 (JP, A) JP-A-11-147027 (JP, A) JP-A-4-20705 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23G 7/06 B01D 50/00 501 F23J 15/00

Claims (6)

(57) [Claims] 1. A system for purifying low-temperature combustible gas emissions and high-temperature combustible gas emissions generated in a chemical process and releasing it into the atmosphere, comprising: a self-standing housing having an upper chamber and a lower chamber; A low-temperature combustor provided in the chamber, for introducing the low-temperature combustible gas exhaust gas, thermally decomposing at a first temperature, and then discharging to the outside;
A high-temperature combustor for introducing a high-temperature combustible gas emission and thermally decomposing at a second temperature higher than the first temperature, and then discharging the high-temperature combustor to the outside; A fuel gas generator for supplying to the high-temperature combustor. 2. The apparatus according to claim 1, further comprising a dust collector disposed at an outlet end of the low temperature combustor for collecting and removing fine particles in a pyrolysis gas discharged from the low temperature combustor.
A combined gas treatment system as described. 3. The scrubber according to claim 1, further comprising a wet scrubber disposed at an outlet end of the high-temperature combustor for purifying a pyrolysis gas discharged from the high-temperature combustor by contacting with moisture. Complex gas treatment system. 4. A high temperature combustor comprising: a cylindrical casing having a central combustion chamber, an inlet end and an outlet end; and a cylindrical heater element disposed coaxially in a longitudinal direction of the cylindrical casing. 2. The composite according to claim 1, further comprising a fuel injection nozzle provided at an inlet end of the casing for injecting fuel gas into a central combustion chamber of the casing, and connected to the fuel gas generator. Gas treatment system. 5. The fuel gas generator includes an electrolyzer for decomposing water into oxygen gas and hydrogen gas, the electrolyzer being provided with a fuel injection nozzle of the high temperature combustor through a flashback prevention tank filled with water. 5. The combined gas processing system according to claim 4, wherein oxygen gas and hydrogen gas are supplied to the gas. 6. The flashback prevention tank has a lower inlet connected to the electrolyzer for introducing fuel gas and an upper outlet connected to a fuel injection nozzle of the high temperature combustor. The composite gas treatment system according to claim 5, wherein