To further enhance a recovery rate of methane finally recovered from biogas.
Biogas is pressurized and supplied to a first stage separation membrane module 1 via a supply tube 4 and a first compressor 5, a transmitted gas transmitted through the first stage separation membrane module 1 and containing carbon dioxide much is compressed by a second compressor 9 and cooled by a cooler 10 to liquefy and recover carbon dioxide in the transmitted gas, and residual transmitted gas is recycled again to the first stage separation membrane module 1 via a first recycle tube 7 and the supply tube 4. A non-transmitted gas which is not transmitted through the first stage separation membrane module 1 and contains methane much is supplied to a second stage separation membrane module 2 by residual pressure via a non-transmitted gas tube 8, a transmitted gas transmitted through the second stage separation membrane module 2 and containing carbon dioxide much is recycled to the first stage separation membrane module 1 via a second recycle tube 11 and the supply tube 4 and a non-transmitted gas which is not transmitted through the second stage separation membrane module 2 and contains methane much is recovered by a recover tube 12 as a methane concentrated gas.
MIZUNO SHIHO
MORIOKI MASAKATSU
UMEDA YOSHITO
| JP2007254572A | 2007-10-04 | |||
| JP2001294873A | 2001-10-23 | |||
| JPH113723A | 1999-01-06 | |||
| JPH09124514A | 1997-05-13 | |||
| JP2001000949A | 2001-01-09 |
| WO2010021053A1 | 2010-02-25 |