Sinusoidal and pulse response of a plate distillation column by reflux upset

Abstract

A study was made to evaluate pulses 0 s a forcing function on a 24-plate distillation column.Pulses of two shapes, rectangular and displaced cosines, and of different widths were used as inputs to the reflux return line from the condenser to the column. The effect of the disturbance was a change in the liquid return rate which correspond to the shape and size of the pulse. The output responses of the system were temperatures measured a t different times and a t different plates in the column.Bode diagrams were platted from the experimentally determined data. From these plots, it was determined that the system could be approximated by linear first-order equations. The time constants for the linear system were determined both by direct sinusoidal forcing and by pulse forcing. Pulse data were considered acceptable when the values of the time constant and the phase angle determined by the pulse compared favorably with those determined by steady state sinusoidal forcing.The application of pulse inputs to determine the dyiiamic response of a chemical process system is a known technique in the chemical and petroleum industries. From a theoretical standpoint, the technique makes it possible to define the frequency response over the entire frequency range for a system with the use of a single pulse. This has been demonstrated by Dreifke (1 ) , and Clements and Schnelle ( 2 ) through the analytical analysis of various mathematical models which they subjected to different pulses readily determined. From such studies one can see