A method for revamping a CO2 removal section for removing carbon dioxide from a hydrogen-containing synthesis gas, wherein: said CO2 removal section comprises an absorption section wherein carbon dioxide is removed from the synthesis gas by absorption in an absorbing solution, obtaining a CO2-rich solution, and a stripper for regeneration of the CO2-rich solution, comprising an upper zone where said solution coming from the absorber is flashed producing a first gaseous stream containing CO2 and a partially regenerated semi-lean solution, and a lower zone acting as a stripping zone where the semi-lean solution is stripped producing a second gaseous stream containing CO2 and a lean regenerated solution, said second gaseous stream having a hydrogen content which is lower than the hydrogen content of said first gaseous stream, the method of revamping comprising the provision of sealing means arranged to isolate said second gaseous stream from said first gaseous stream and to export said first stream and second stream separately from the stripper, and wherein said sealing means include partitioning means (17, 30) arranged to partition the upper zone into a flashing zone (21, 32) and a chamber (22, 33), the CO2-rich solution is fed to said flashing zone wherein the flashing takes place, the first gaseous stream is collected and the semi-lean solution is generated; said flashing zone (21, 32) communicates with said chamber via at least one aperture (23, 31) arranged to feed the semi-lean solution from the flashing zone to the chamber; said chamber (22, 33) is in communication with the stripping zone so that the second gaseous stream is collected into said chamber and the semi-lean solution flows from the chamber (22, 33) to said stripping zone; the method of revamping being characterized in that said partitioning means include a gas collector located in the upper zone, said flashing zone being delimited inside the gas collector and said chamber being defined outside the gas collector in the upper zone, said gas collector having a bottom opening which represents said at least one aperture for communication between the flashing zone and the chamber. said CO2 removal section comprises an absorption section wherein carbon dioxide is removed from the synthesis gas by absorption in an absorbing solution, obtaining a CO2-rich solution, and a stripper for regeneration of the CO2-rich solution, comprising an upper zone where said solution coming from the absorber is flashed producing a first gaseous stream containing CO2 and a partially regenerated semi-lean solution, and a lower zone acting as a stripping zone where the semi-lean solution is stripped producing a second gaseous stream containing CO2 and a lean regenerated solution, said second gaseous stream having a hydrogen content which is lower than the hydrogen content of said first gaseous stream, the method of revamping comprising the provision of sealing means arranged to isolate said second gaseous stream from said first gaseous stream and to export said first stream and second stream separately from the stripper, and wherein said sealing means include partitioning means (17, 30) arranged to partition the upper zone into a flashing zone (21, 32) and a chamber (22, 33), the CO2-rich solution is fed to said flashing zone wherein the flashing takes place, the first gaseous stream is collected and the semi-lean solution is generated; said flashing zone (21, 32) communicates with said chamber via at least one aperture (23, 31) arranged to feed the semi-lean solution from the flashing zone to the chamber; said chamber (22, 33) is in communication with the stripping zone so that the second gaseous stream is collected into said chamber and the semi-lean solution flows from the chamber (22, 33) to said stripping zone; the method of revamping being characterized in that said partitioning means include a gas collector located in the upper zone, said flashing zone being delimited inside the gas collector and said chamber being defined outside the gas collector in the upper zone, said gas collector having a bottom opening which represents said at least one aperture for communication between the flashing zone and the chamber.