Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture
Patent
1996-06-04
1998-09-01
Tran, Hien
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
4232405, 4232453, 422109, 422110, 422168, 422173, 422174, 422178, 422212, 422171, C01B 33113, B01D 5334
Patent
active
058007920
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an exhaust gas treatment unit for subjecting an exhaust gas discharged from a semiconductor manufacturing installation or the like to a treatment for removing harmful substances, and more particularly, to an exhaust gas treatment unit for removing harmful gases such as monosilane (SiH.sub.4), phosphine (PH.sub.3), hydrogen nitride (NH.sub.3) and nitrogen fluoride (NF.sub.3) contained in an exhaust gas by thermally oxidative decomposition.
DESCRIPTION OF THE RELATED ART
In the manufacture of semiconductors, an exhaust gas is generated which contains noxious gases such as SiH.sub.4, PH.sub.3, NH.sub.3 and NF.sub.3. In accordance with the law (High Pressure Gas Control Law), manufacturers are obligated to install an exhaust gas treatment unit in order to treat the discharged exhaust gas and to discharge the exhaust gas only after the noxious gases have been removed or made harmless. The law sets Threshold Limit Values (TLV) for noxious gases which are the maximum allowable amounts of these gases which may be present in discharged exhaust gases. Known types of exhaust gas treatment units for removal of these gases include a chemical reaction type treatment unit for removing noxious gases by an oxidative or neutralization reaction using a neutralizing agent such as metal oxides or caustic soda (sodium hydroxide). Other known types of exhaust gas treatment units include wet scrubber type units or combustion type units which burn the exhaust gas using a gas burner.
In conventional exhaust gas treatment units, such as those mentioned above, there are various problems. In a chemical reaction type treatment unit high expense and substantial labor are required for exchanging the chemical agents or metal oxides used in the treatment. In the case of a wet scrubber type treatment unit, large amounts of washing water and an absorbing liquid are required. In addition, a waste water treatment installation is necessary to treat the washing water.
In the case of a combustion type treatment unit, a combustion improver such as hydrogen or methane and a large amount of air or oxygen are necessary for combustion. A water cooling installation is also necessary for cooling the exhaust gas because the exhaust gas exit temperature in a is combustion type treatment unit is high. Furthermore, there is a problem with combustion treatment in that deposits such as reaction products are easily deposited on the inside of a combustion reactor which must be periodically removed.
OBJECTS AND SUMMARY
It is therefore an object of the present invention to produce an exhaust gas treatment unit in which the aforementioned problems are addressed.
In order to achieve the aforementioned object according to the present invention, an exhaust gas treatment unit for removing noxious gases contained in an exhaust gas by thermal decomposition includes a heating drum into which the exhaust gas and oxygen are introduced, a heating source disposed on the outer periphery of the heating drum so as to heat the inside of the heating drum, a temperature detection means for detecting the temperature of the inside of the heating drum in the vicinity of its outlet, a control means for controlling the heating source in accordance with a detected value from the temperature detection means so that the temperature of the inside of the heating drum in the vicinity of its outlet is maintained within a predetermined temperature range, and an air-cooled type cooling device connected to the outlet of the heating drum. In addition, the predetermined temperature range within the heating drum is preferably 350.degree. C..about.500.degree. C.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
The invention will be described in greater detail with reference to the accompanying drawings, wherein:
FIG. 1 is a schematic view of one embodiment of the exhaust gas treatment unit according to the present invention; and
FIG. 2 is a graph of experimental results obtained by using the exhaust gas treatment unit according to the present
REFERENCES:
patent: 2141873 (1938-12-01), Modine
patent: 2258790 (1941-10-01), Murphy
patent: 3052105 (1962-09-01), Bowman et al.
patent: 4420313 (1983-12-01), Hada et al.
patent: 5538702 (1996-07-01), Smith et al.
Ibaraki Yoshihiro
Ina Hidekazu
Kawanaka Hideji
Teisan Kabushiki Kaisha
Tran Hien
LandOfFree
Exhaust gas treatment unit and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Exhaust gas treatment unit and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Exhaust gas treatment unit and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-267136