
438 Appendix C: Unit Operations in a Re-Refinery
deposits can arise from the additives that are present in the lube oils and can be dif-
cult to handle in a distillation column: this led to the interest in and application of
wiped lm evaporators in many cases.
C.1.5.2 Wiped-Film Evaporators
The wiped lm evaporator is not as versatile as the distillation column in that it
results in an overow and an underow product stream, but it has a number of advan-
tages that can be important for recycled oil treatment. The feed enters the top of the
cylindrical vessel shown in Figure C.4 and ows down the walls. A jacket around
this cylindrical vesse