Natural gas fractionation involving a dephlegmator.

摘要

A process for the fractionation of a gas, e.g. natural gas, comprises the steps of, cooling the gas E1, E5, separating the gas 5 into first gas 6 and liquid 7 phases, sending at least a part of the first gas phase to an expansion stage X1 to obtain a mixed phase, warming the mixed phase P1 in a dephlegmator D1 where it cools a second gas phase P2, separating B1 the mixed phase into the second gas phase P2 and a second liquid phase 14 and fractionating the second gas phase by rectification in the dephlegmator to provide a rectified gas. The liquid phases may be separated 9 to provide a third gas phase 10 which may be combined with the second gas phase for rectification in the dephlegmator. This separation may be carried out in a stabiliser column 9 or a second dephlegmator (40, Fig. 3). The rectified gas may be passed back P3 through the dephlegmator to provide additional cooling.