The invention concerns a process for fractionating hydrocarbon feeds employing at least one fractionation zone provided with separation contact means, and at least two switchable bottom zones which can be connected to the bottom of the fractionation zone in a manner such that at least a first of the bottom zones operates with said fractionation zone, in alternation, for a period at most equal to a plugging period, in a manner such that when at least the first of the bottom zones becomes plugged or before it becomes plugged, it is disconnected from the fractionation zone in order to be cleaned while the feed fractionation process continues with at least one other of the bottom zones.