Process and installation for separation of a gas mixture containing methane by distillation
AssigneeTechnip-Coflexip
InventorHenri Paradowski
Life of this patent
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Abstract
A process and apparatus for separation of a gas mixture. A process and an installation for cryogenic separation of the constituents of a natural gas under pressure in a first phase separator in which the constituents of each phase are separated in a distillation column. Part of the gaseous fraction from the top of the column is recycled into the highest stage of the column. The process also includes branching of part of a first top fraction from the first phase separator. The process also includes separation of a first bottom fraction from the first separator, in a second separator.
Claims12
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.
An apparatus for separation of a mixture cooled under pressure containing methane and C2 and higher hydrocarbons, into a methane-rich light fraction and a heavy fraction rich in C2 and higher hydrocarbons, comprising:
- in a first stage including a distillation column in which the mixture cooled under pressure is present, means for separating the mixture, in a first flask, into a relatively more volatile first top fraction and a relatively less volatile first bottom fraction, the first bottom fraction being introduced into a middle part of the distillation column in which, in a lower part of the column, the final heavy fraction rich in C2 and higher hydrocarbons are collected as the second bottom fraction, a turbine reducing pressure of the first top fraction for introducing, after the pressure reduction, the first top fraction into an upper part of the distillation column, for collecting a second methane-rich top fraction in the upper part of the distillation column, a compressor and cooler for compressing and cooling the second top fraction to produce the light fraction, and for taking a first sample fraction from the light fraction;
- means, in a second stage, for introducing the first sample fraction, after cooling and liquefaction, into the upper part of the distillation column;
- and
- in a third stage, means for subjecting the first bottom fraction to heating, passage into a second flask, and separation into a relatively more volatile third top fraction and a relatively less volatile third bottom fraction, wherein the third bottom fraction is introduced into the middle part of the distillation column, and the third top fraction is introduced into the upper part of the distillation column, after cooling and liquefaction.
Dependencies are inferred from the claim text.