Method and apparatus for treating perfluorocompounds

Abstract

In a PFC decomposing apparatus according to the present invention, PFC contained in a discharged gas is decomposed in catalyst cartridge 3 packed with a catalyst containing 80% Al 2 O 3 and 20% NiO. The discharged gas containing acid gases as a decomposition gas is cooled in cooling chamber 6 and led to discharged gas washing column 13, where the acid gases are removed. Mists of acid gases (SO 3 mists or NOx mists) entrained in the discharged gas are separed in cyclone 16. Compressed air at about 0.1 Mpa is fed to ejector 24 through air feed pipe 56. The interior of ejector 24 is brought into a negative pressure state by the compressed air to such the discharged gas from cyclone 16 and ejector. Ejector 24 can reduce a frequency of maintenance inspection, as compared with a blower.

What is claimed is:  
     
         1 . A method for treating perfluorocompounds, which comprises a step of decomposing perfluorcompounds contained in a gas and a step of sucking a discharged gas containing acid gases resulting from the decomposition of the perfluorocompounds by a jet stream of an injected gas, thereby ejecting the sucked gas.  
     
     
         2 . A method for treating perfluorocompounds, which comprises a step of decomposing perfluorocompounds contained in a gas, a step of bringing the discharged gas containing acid gases resulting from the decomposition of the perfluorocompounds into contact with one of water and an aqueous alkaline solution, thereby removing the acid gases from the discharged gas, a step of separating mists contained in the discharged gas after the contact with one of the water and the aqueous alkaline solution, and a step of sucking the discharged gas separated from the mists by a jet stream of an injected gas, thereby ejecting the sucked gas.  
     
     
         3 . A method according to  claim 1 , wherein the perfluorocompounds are catalytically decomposed.  
     
     
         4 . A method according to  claim 1 , wherein the step of sucking the discharged gas by a jet stream of the injected gas, thereby ejecting the sucked gas is carried out by an ejector.  
     
     
         5 . A method for treating a discharged gas from a semiconductor production plant, which comprises a step of decomposing perfluorocompounds contained in a discharged gas from a semiconductor production plant and a step of sucking the discharged gas containing acid gases resulting from the decomposition of the perfluorocompounds by a jet stream of an injected gas, thereby ejecting the sucked discharged gas.  
     
     
         6 . A method for treating a discharged gas from a semiconductor production plant, which comprises a step of decomposing perfluorocompounds contained in a discharged gas from a semiconductor production plant, a step of bringing the discharged gas containing acid gases resulting from the decomposition of the perfluorocompounds into contact with one of water and an aqueous alkaline solution, thereby removing the acid gases from the discharged gas, a step of separating mists contained in the discharged gas after the contact with one of the water and the aqueous alkaline solution, and a step of sucking the discharged gas separated from the mists by a jet stream of an injected gas, thereby ejecting the sucked discharged gas.  
     
     
         7 . A method according to  claim 5 , wherein the perfluorocompounds are catalytically decomposed.  
     
     
         8 . A method according to  claim 5 , wherein the discharged gas is sucked by the jet stream of the injected gas and ejected by an ejector.  
     
     
         9 . An apparatus for treating perfluorocompounds, which comprises a perfluorocompounds decomposing apparatus for decomposing perfluorocompound contained in a gas fed thereto, and a gas suction apparatus for sucking the discharged gas containing acid gases resulting from the decomposition of the perfluorocomopunds by a jet stream of an injected gas, thereby ejecting the gas.  
     
     
         10 . An apparatus for treating perfluorocompounds, which comprises a perfluorocompounds decomposing apparatus for decomposing perfluorocompounds contained in a gas fed thereto, an acid gas removing apparatus for removing acid gases resulting from the decomposition of the perfluorocompounds from the discharged gas, and a gas suction apparatus for sucking the discharged gas in the acid gas removing apparatus by a jet stream of an injecting gas, thereby ejecting the gas.  
     
     
         11 . An apparatus according to  claim 10 , wherein the acid gas removing apparatus is carried out by bringing the discharged gas containing the acid gases into contact with one of water and an aqueous alkaline solution, thereby removing the acid gases from the gas, and a mist separation apparatus for separating mists from the gas discharged from the acid gas removing apparatus by suction by the gas suction apparatus is further provided.  
     
     
         12 . An apparatus according to  claim 11 , wherein tank for receiving one of the water and the aqueous alkaline solution from the acid gas removing apparatus and a discharging piping leading the mists separated in the mist separating apparatus to the tank are further provided below the acid gas removing apparatus and the mist separating apparatus.  
     
     
         13 . An apparatus according to  claim 9 , wherein the perfluorocompound decomposing apparatus is packed with a catalyst acting to decompose the perfluorocompounds.  
     
     
         14 . An apparatus according to  claim 13 , wherein the catalyst contains an Al oxide and further one oxides of metals selected from Zn, Ni, Ti, F, Sn, CO, Zr, Ce, Si and Pt.  
     
     
         15 . An apparatus according to  claim 9 , wherein the gas suction apparatus is an ejector.  
     
     
         16 . An apparatus according to  claim 15 , wherein a means of stopping feeding of driving gas to the ejector, when the pressure of the driving gas to the ejector exceeds a set pressure is further provided.