Modelling dynamic feeding in cyclic separation

Modelling of cyclic separations is extended to account for a non-instantaneous liquid feeding period succeeding the liquid flow period in established models. The inclusion of variable holdup infers inter-tray variations and time-variant behaviour. For a linear case of ammonia stripping, we employ solution methods involving state-transition matrices derived using a Peano–Baker series expansion to retain linear solution methods for determining the pseudo-steady-states. The expanded model is then utilised to evaluate the impact of prolonged feeding relative to prolonged liquid flow periods on separation performance for established simultaneous and sequential draining strategies. Accounting for the non-instantaneous behaviour showed improved agreement with experimental results and illuminated that prolonged feeding can significantly reduce the overall column separation performance.