Process for starting up a carbon capture process

A process for starting up a carbon capture process wherein in the carbon capture process under normal operation:

• i) a gaseous mixture containing CO2, at least one component heavier than CO2 and at least one component lighter than CO2 is compressed, dried, cooled in a heat exchanger, separated in a washing column to form a feed stream containing proportionally less of the at least one component heavier than CO2 than the gaseous mixture, the feed stream containing proportionally less of the at least one component heavier than CO2 than the gaseous mixture being separated by a least one partial condensation step forming a liquid enriched in CO2 with respect to the feed stream and a gas enriched in the at least one component lighter than CO2 with respect to the feed stream;
• ii) the gas enriched in the at least one component lighter than CO2 is warmed in the heat exchanger and then expanded in a turbine, emerging from the turbine at a first temperature and is sent to the atmosphere or to a cooling tower;
• wherein during start-up, a gas expanded in the turbine is produced at a second temperature differing from the first temperature by at least 1° C. but lower than 0° C., the expanded gas being then warmed in the heat exchanger or sent to the distillation column of the carbon capture process to cool down the distillation column.