Simulation and experimental study of intermediate heat exchange in a sieve tray distillation column

Publisher Summary This chapter combines a simulation study with an experimental study in the investigation of intermediate heat exchange as a method to change the distribution of the driving forces in the column. It was applied to a pilot plant sieve tray distillation column for a binary separation of ethanol from n-propanol. Intermediate heat exchange has been accomplished experimentally both in the stripping section and in the rectifying section. Optimal side-stream return in intermediate heat exchange is discussed in the chapter. When comparing experimental results from the pilot plant column to simulation results, the inclusion of tray efficiency is of interest. For this purpose, a calculation routine was developed in MATHCAD based on a correlation by Chan and Fair. The resulting data was then transferred to the PRO II simulation program. The results show that intermediate heat exchange can be used to improve the recovery and the separation capacity and to decrease the entropy production if the points of side-stream withdrawal and side-stream return are chosen properly. It is important that the heat-exchanged liquid stream returned as vapor enters at a position in the column where the vapor phase has the same composition. Even if the composition coincides, the actual position for an added vapor stream is important for the flow profiles in the column.