The device comprises at least one column 1 that is filled with a number of beds An, whereby each bed Ai is separated from the next bed Ai+1 by a fluid distributor plate Pi. Each plate is divided into a number of sectors P10, and P11, and each sector comprises at least two fluid distribution chambers CHi and CHj. Each chamber of the plate is connected to a transfer line LTi and LTj to the outside. Transfer line LTi, which is associated with chambers CHi of a distributor plate, is connected to transfer line LTj, which is associated with chambers CHj of the same plate, via a bypass line Li,j. The latter comprises means 14, 15, 16, and 17 for controlling and adjusting the flow rate of fluid that circulates there, such that each distribution chamber CHi is flushed by a fluid that is obtained from chamber CHj and that has approximately the same composition as that of the fluid that circulates through distributor plate Pi at each of the chambers.