the condenser 8 the dry air is sucked in again by the blower 3 the receptacle 7 illustrated in fig2 in cross section and in fig3 in a plan view showing the surface of the insert 13 serves as a holding frame for the odor filter 13 for such a purpose the holding frame 7 receives a sheet like dish shaped frame 11 the bottom of which as a crossed rib structure 18 has large orifices for the passage of the process air a foldable holder 12 is interlocked in the frame 11 the holder 12 may be of a high grade steel wire mount its meshes have a width comparable to that of the orifices of the crossed rib structure 18 as a result although the holder 12 covers substantially the entire bottom of the frame 11 nevertheless in the folded down state its orifices are congruent with the orifices in the frame 11 an odor filter 13 in the form of a piece of nonwoven or textile material is retained illustrated only partially in fig3 between the frame 11 and the holder 12 to produce the odor binding property the nonwoven like or textile like odor filter 13 is treated or covered with a substance for example activated charcoal that.