Elevating the flexibility and operability of dividing-wall distillation columns via feed thermal condition adjustment

Because of the complicated interplay between the prefractionator and main distillation column involved,the black-hole problem might occur and prohibit the assignment of four specifications to dividing-wall distillation columns(DWDCs)(e.g., the three main product compositions plus an impurity ratio in the intermediate product), which lowers terribly process flexibility and operability. In this paper, a feed thermal condition adjustment strategy, achieved by the installation of a pre-heater in feed pipeline, is employed to eliminate the black-hole problem and serve to enhance process flexibility and operability. Through the strong influence to the overall mass and energy balance of the DWDC, the feed thermal condition adjustment can alter the interlinking flows between the thermally coupled prefractionator and main distillation column and work effectively to coordinate their relationship. A DWDC separating a benzene, toluene, and o-xylene mixture is chosen to ascertain the feasibility of the philosophy proposed. The static and dynamic studies demonstrate that the feed thermal condition adjustment is an effective way to refine process design and can completely eliminate the black-hole problem and elevate consequently process flexibility and operability.

Many-lined Sun Skinks(Mabuya multifasciata) Shift Their Thermal Preferences Downwards When Fasted

We maintained adult many-lined sun skinks(Mabuya multifasciata; 12 females and 12 males) collected from Hainan(southern China) in September 2006 in two outdoor enclosures to examine the effect of feeding condition on selected body temperature(Tsel).Skinks shifted their thermal preferences when fasted.Temporal variation in Tsel was not found within each sex feeding condition combination,and neither in fed nor in fasted skinks did the mean values for Tsel differ between sexes.Body temperatures selected by fed skinks fell within the range from 30.2 to 33.9 C,and those selected by fasted skinks within the range from 25.1 to 31.8 C.Body temperatures(31.8 0.3 C) selected by fed skinks were on average 4.0 C higher than those(27.8 0.4 C) selected by fasted skinks.Fasted skinks had no difficulty in attaining higher body temperatures,but they voluntarily shift their thermal preferences downwards to save energy.This finding suggests an adaptive mechanism adopted by many-lined sun skinks to enhance their fitness during the periods when food availability is low.