| 摘要 |
PROBLEM TO BE SOLVED: To enable SF6 to be efficiently separated/recovered and thereby reduce the emission amount of the SF6 into an atmosphere by supplying a mixed gas made up of an electrically insulating gas containing a specific amount of the SF6 to a gas separating membrane to establish their mutual contact and recovering a gas containing the SF6 of a specific purity from the impermeable side of the membrane. SOLUTION: When SF6 is efficiently recovered by separation, a mixed gas consisting of the SF6 and another gas is supplied from the mixed gas supply aperture 3 of a gas separation device 1 and is fluidized to an impermeable gas discharge aperture 4 side through the inside of a hollow fiber 2. The gas permeating through a separation membrane is discharged from a permeable gas discharge aperture 5, while the gas not permeating through the separation membrane is discharged from an impermeable gas discharge aperture 4 and thus the SF6 whose permeation velocity is low is recovered by separation. In this case, the concentration of the SF6 in the mixed gas is set to be 6-60 vol.% and the SF6 amount to be discharged from the membrane permeation side is set to be 3 vol.% or less of the mixed gas before separation. Besides, the mixed gas is treated so that the purity of the SF6 in the SF6-rich gas to be recovered to the membrane impermeation side is equivalent to 80 vol.% or more.
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