Patent ID: 8828350
Filing Date: 2014-09-09
Classification: C01B

Abstract:
1. A system for recovering a re-usable grade of sulphur hexafluoride from a potentially contaminated gas present in a sulphur hexafluoride gas source, said system comprising: at least one extraction vessel including a gas inlet and a gas outlet, said gas inlet being adapted to be connected to said sulphur hexafluoride gas source; a first cryogenic means for reducing the temperature of said at least one extraction vessel to a temperature below phase transition of sulphur hexafluoride gas, wherein at said cryogenically reduced temperature the pressure in said at least one extraction vessel is less than the sulphur hexafluoride gas source pressure thereby causing said potentially contaminated gas to enter said at least one vessel via said gas inlet, the sulphur hexafluoride included in said potentially contaminated gas turning into liquid and/or solid form in said at least one extraction vessel; evacuation means for evacuating any non-condensed contaminant gas from said at least one extraction vessel via said gas outlet while said at least one extraction vessel is at said cryogenically reduced temperature; means for raising the temperature of said at least one extraction vessel from said cryogenically reduced temperature to substantially a dewpoint temperature after evacuating said non-condensed gas, wherein at said dewpoint temperature a re-usable grade of sulphur hexafluoride gas is present in said at least one extraction vessel and any condensable contaminants are in liquid and/or solid form, and wherein raising the temperature substantially to the dewpoint temperature raises the pressure in the at least one extraction vessel; at least one recovery vessel including a gas inlet being adapted to be connected to said gas outlet of said at least one extraction vessel; and a second cryogenic means for reducing the temperature of said at least one recovery vessel to a temperature below phase transition of sulphur hexafluoride, wherein at said cryogenically reduced temperature the pressure in said at least one recovery vessel is less than the pressure in said at least one extraction vessel when substantially at said dewpoint temperature, wherein connecting the gas inlet of said at least one recovery vessel to the gas outlet of said at least one extraction vessel allows said re-usable grade of sulphur hexafluoride to enter said at least one recovery vessel, wherein the system is capable of flowing gas from the at least one extraction vessel to the at least one recovery vessel, the flow of gas being outside of the sulphur hexafluoride gas source, wherein the second cryogenic means is in addition to the first cryogenic means.