the end of the drying process the drying process using the so called multiple transverse stirring there is admitted in the zone of completion of the drying process a first air flow the additional or major air flow being admitted in a zone where the product has lost most of its moisture content the first air flow being heated at 8 to a high temperature the additional air flow being heated to a mean temperature and the entire air flow being subjected to heat inputs 8 at a mean temperature derived from at least one heat pump the invention reduces the heat input required for such a process application_number US 59062184 A description the plant such as basically illustrated in fig3 includes an elongated enclosure 1 having arranged therein a conveyor which is here represented by the upper run of a conveyor belt 2 having disposed thereon as a bed 3 the product to be dried the conveyor belt and the bed being air permeable the conveyor could be of any other type such as the scoop or rack type pneumatic type fluidized bed type etc depending on the nature and form of the material to be dried the product is fed into the enclosure through an inlet e and removed therefrom through an outlet s it may flow either continuously or stepwise provided that it remains within the enclosure during the time required for the thermal exchanges the enclosure is sub divided into four zones i to iv the nature of which will be explained hereinafter it includes two air inlets 4 and 5 the first being in register with zone iv and the second lying between zones i and ii and an air outlet 6 in zone i adjacent to the inlet e of the.