DECOMPOSITION OF THERMALLY UNSTABLE SUBSTANCES IN FILM EVAPORATORS.

IT IS WIDELY KNOWN THAT FILM EVAPORATORS ARE CONSIDERED TO PERMIT REALLY GENTLE EVAPORATION OF HEAT-SENSITIVE SUBSTANCES. NEVERTHELESS, DECOMPOSITION OF SUCH SUBSTANCES STILL OCCURS TO AN EXTENT DEPENDING UPON THE DESIGN AND OPERATION OF THE EVAPORATOR. IN THE FOLLOWING A DISTINCTON IS MADE BETWEENEVAPORATORS WITH FILMS NOT GENERATED MECHANICALLY, NAMELY THE LONG TUBE EVAPORATOR (LTE) OR CLIMBING FILM EVAPORATOR, THE FALLING FILM EVAPORATOR (FFE) AND THE MULTIPLE PHASE HELICAL TUBE (MPT) OR HELICAL COIL EVAPORATOR, AND EVAPORATORS WITH MECHANICALLY GENERATED FILMS, E. G. THIN OR WIPED FILM EVAPORATORS (TFE). A THEORY OF THE DECOMPOSITION OF THERMALLYUNSTABLE SUBSTANCES IN THESE EVAPORATORS IS BRIEFLY OUTLINED AND COMPARED WITH MEASUREMENTS.