The invention relates to an equipment for fractionating a solution by a sequential SMB process, which equipment comprises a feed column and one or several other columns, which include a chromatographic separation resin bed. The equipment of the invention is characterized in that the feed column consists of or comprises a compartment where the resin bed is shallower than that of one or more of the other columns of the equipment. The invention also relates to a method for fractionating a solution into two or more fractions with the equipment of the invention.