Method For Separating A Mixture Of Carbon Monoxide, Methane, Hydrogen And Optionally Nitrogen by Cryogenic Distillation

A method for separating a mixture comprising at least carbon monoxide, hydrogen and methane in which the mixture is separated by a first separation means, at least one liquid fraction from the bottom of the separation means is sent to a stripping column, at least one portion of the liquid fraction from the stripping column is sent to a CO/CH4 separation column in order to produce a liquid stream enriched in methane and a gas stream enriched in carbon monoxide, the method being kept cold at least partially by a carbon monoxide cycle, said cycle at least partially providing at least one source of heat transfer selected from the group consisting of the condensation at the top of the CO/CH4 separation column, the reboiling at the bottom of the stripping column, reboiling at the bottom of the CO/CH4 separation column, and the cooling of the mixture intended for the first separation means.

The method of claim 39, in which the mixture to be separated in the methane scrubbing column is cooled by heat exchange with a stream of carbon monoxide of the cycle with a pressure of at least about 2 bar.

An installation for separating a mixture comprising at least carbon monoxide, hydrogen and methane comprising a first separation, a stripping column, a CO/CH4 separation column, a line for sending the mixture to the first separation means, a line for sending at least one liquid fraction from the first separation means to the stripping column, a line for sending at least one portion of the liquid fraction from the stripping column to the CO/CH4 separation column in order to produce a liquid stream enriched in methane and a gas stream enriched in carbon monoxide, and a line for withdrawing the gas stream enriched in carbon monoxide from the CO/CH4 separation column, the installation being kept cold at least partially by a cycle of carbon monoxide, said cycle at least partially providing at least one source of heat transfer selected from the group consisting of the condensation at the top of the CO/CH4 separation column, the reboiling at the bottom of the stripping column, reboiling at the bottom of the CO/CH4 separation column, and the cooling of the mixture intended for the first separation means.

The installation of Icaim 46, in which the mixture further comprises nitrogen and comprising a denitrogenation column and a line for sending the gas stream enriched in carbon monoxide to the denitrogenation column in order to produce a carbon-monoxide-rich liquid stream and a nitrogen-rich gas stream, said carbon monoxide cycle at least partially providing the cooling of an overhead condenser of the denitrogenation column.