A macroscopic model for countercurrent gas‐liquid flow in packed columns

A macroscopic model based on the volume‐averaged equations of motion is presented for countercurrent gas‐liquid flow in a packed bed. The model yields a column‐limited flooding point as the loss of existence of uniform states. It correctly predicts the existence of two uniform states below the flooding point. The lower branch corresponds to the trends commonly observed experimentally. It is shown that the upper branch is made unattainable by the gas distributor/support plate at the bottom of the column. The occurrence of premature flooding induced by the support plate is also explained. It is suggested that the occurrence of spontaneous liquid segregation, necessitating frequent liquid redistribution in columns with large dumped packings and porosities, is a consequence of the loss of stability of the uniform state in the lower branch.