Unsteady-state models of gas absorption columns

The unsteady-state equations for a plate gas absorption column are formulated. The equations take into account imperfect plate efficiencies and liquid flow changes. Transfer-function and state-variable models of the column are derived. Experimental frequency responses are obtained on a 4-in. i.d., six-plate laboratory absorption column operating with the system air–ammonia–water and are compared with the theoretical responses. The unsteady-state equations for a packed gas absorption column are also formulated, taking into account variations of mass transfer coefficient and interfacial area and liquid flow changes. A transfer-function model of the column is derived. [Continues.]