Separation method

A process for producing a carbon dioxide-enriched gas from a feed synthesis gas comprising at least one condensable component, and especially hydrogen, the process comprising the following steps:

• a) introduction into a unit for separation by pressure swing adsorption of a de-saturated synthesis gas obtained from the feed synthesis gas;
• b) separation by the pressure swing adsorption separation unit of the de-saturated synthesis gas into a first fraction and a carbon dioxide-enriched residual gas;
• c) compression of the residual gas with at least two compression stages and cooling of the compressed residual gas at at least one intermediate compression stage;
• characterized in that the process further comprises:
• a desaturation step during which at least a portion of the condensable component contained in the feed synthesis gas is condensed, upstream of said pressure swing adsorption separation unit, by cooling to a temperature of less than 10° C., especially less than or equal to 5° C., and separated, producing said de-saturated synthesis gas and at least one condensate;
• the feed synthesis gas undergoing heat exchange with the de-saturated synthesis gas so as to heat said de-saturated synthesis gas upstream of the pressure swing adsorption separation unit.

An installation for production of a carbon dioxide-enriched gas from a feed synthesis gas comprising at least one condensable component and especially hydrogen, the installation comprising:

• a pressure swing adsorption separation unit configured to separate a de-saturated synthesis gas, obtained from the feed synthesis gas, into a first fraction and a carbon dioxide-enriched residual gas;
• a compression device arranged downstream of the pressure swing adsorption separation unit, the compression device comprising at least two stages for compressing the residual gas and at least one intermediate exchanger for cooling the compressed residual gas at an intermediate compression stage;
• characterized in that the installation comprises:
• upstream of the pressure swing adsorption separation unit, a condensation by cooling and separation device configured to condense and separate at least a portion of the condensable component contained in the feed synthesis gas and produce the de-saturated synthesis gas and at least one condensate;
• an economizer exchanger arranged to bring about heat exchange between the feed synthesis gas and the de-saturated synthesis gas.