| 摘要 |
A process for separation of particularly propane, methane or ethane from natural gas includes providing a distillation tower arrangement (30) for separating the heavier components discharged at the bottom (36) from lighter gas discharged at the top with at least two separate towers (21, 32) at different pressures such that the heavier product from the higher pressure tower (31) is expanded and fed to the lower pressure tower (32). A feed gas (10) containing the components under a first pressure is separated into a first proportion (23) and a second proportion (22), where neither proportion is zero. The first proportion (23) is fed to the tower. The second proportion (22) is compressed (45) to a pressure higher than the first pressure, heat is extracted (46) from the compressed second proportion (22) to effect condensation thereof, the compressed condensed second proportion is sub-cooled, expanded (52) to the first pressure and supplied after expansion to the distillation tower arrangement (30) so as to cause cooling of the materials in the distillation tower arrangement (30). The method is particularly advantageous in a low pressure supply system in which the lighter gas discharged at the top of the tower arrangement is supplied at a pressure less than 100 psi and more preferably less than 75 psi.
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