Process for liquefaction of and nitrogen extraction from natural gas, apparatus for implementation of the process, and gases obtained by the process
AssigneeTechnip
InventorHenri Paradowski
Life of this patent
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Abstract
A process for liquefaction of and nitrogen extraction from natural gas, an installation for implementation of the process, and gases obtained by this process. In the process, a first top fraction is cooled and liquefied, separated into a second top fraction which is relatively volatile and which provides gaseous nitrogen, and into a second bottom fraction which is withdrawn. The first bottom fraction is cooled in order to provide liquefied natural gas essentially free nitrogen.
Claims11
A process for liquefaction of and nitrogen extraction from natural gas under pressure containing methane, C2, and higher hydrocarbons and nitrogen in order to obtain liquefied natural gas essentially free of nitrogen, and gaseous nitrogen essentially free of hydrocarbons, the process including
- a first step in which natural gas is cooled, has its pressure reduced, and is liquefied in order to provide pressure-reduced liquefied natural gas flow and the pressure-reduced liquefied natural gas is separated, in a first fractionation column containing a number of stages, into a first top fraction that is more volatile and that is nitrogen enriched, relative to a bottom fraction, and collected in a last stage of the first fractionation column;
- and
- a second step in which the first top fraction is cooled and liquefied in order to provide a first cooled and liquefied fraction, that is separated into a second top fraction that is more volatile and nitrogen enriched relative to a second bottom fraction, the second bottom fraction is introduced into a last stage of the first fractionation column, the second top fraction is heated in order to produce gaseous nitrogen, and, the first bottom fraction is cooled in order to produce liquefied natural gas essentially free of nitrogen.
An apparatus for liquefaction of and nitrogen extraction from natural gas under pressure containing methane, C2, and higher hydrocarbons and nitrogen, for obtaining liquefied natural gas essentially free of nitrogen, and gaseous nitrogen essentially free of hydrocarbons, the apparatus including
- means for carrying out a first step in which natural gas is cooled, has its pressure reduced, and is liquefied in order to provide pressure-reduced liquefied natural gas flow,
- a first fractionation column containing a number of stages and in which the pressure-reduced liquefied natural gas is separated into a first top fraction that is more volatile and that is nitrogen enriched, relative to a first bottom fraction, and is collected in a last stage of the first fractionation column,
- means for carrying out a second step in which the first top fraction is cooled and liquefied in order to provide a first cooled and liquefied fraction, the first cooled and liquefied fraction is separated into a second top fraction that is more volatile and very nitrogen enriched relative to a second bottom fraction, the second bottom fraction is introduced into a last stage of the first fractionation column, the second top fraction is heated in order to produce gaseous nitrogen, and the first bottom fraction is cooled in order to produce liquefied natural gas essentially free of nitrogen.
Dependencies are inferred from the claim text.