Patent ID: 6578379
Filing Date: 2003-06-17
Classification: F25J

Abstract:
A process for separation of a mixture cooled under pressure, containing methane and C2 and higher hydrocarbons, into a methane-rich light fraction and a final heavy fraction rich in C2 and higher hydrocarbons, the process comprising:in a first stage, cooling the mixture under pressure, separating the mixture, in a first flask, into a relatively more volatile first top fraction and a relatively less volatile first bottom fraction, introducing the first bottom fraction into a middle part of a distillation column, collecting in the lower part of the distillation column, the heavy fraction rich in C2 and higher hydrocarbons as a second bottom fraction, introducing, after pressure reduction in a turbine, the first top fraction, in an upper part of the distillation column, collecting, in an upper part of the distillation column, a second methane-rich top fraction, compressing and cooling the second top fraction to produce the light fraction, and taking a first sample fraction from the light fraction; in a second stage, cooling and liquefying the first sample fraction, and introducing the cooled and liquefied first sample fraction into the upper part of the distillation column; and in a third stage, subjecting the first bottom fraction to a number of sub-stages including heating, passage into a second flask, and separation into a relatively more volatile third top fraction, and a relatively less volatile third bottom fraction, introducing the third bottom fraction into the middle part of the distillation column, cooling and liquefying a third top fraction, and introducing the cooled and liquefied third top fraction, after cooling and liquefaction, into the upper part of the distillation column.