AN UNDERWOOD-LIKE MODEL FOR A FINITE MASS EXCHANGER

A mathematical model is presented for a multicomponent, two-stream, co untercurrent mass exchanger with a finite number of stages. The model relates the outlet compositions to the inlet compositions and the flow rate ratio of the two streams going through the exchanger, as well as the number of stages in the exchanger. An iterative solution procedur e employing this model is proposed for the mass exchanger design probl em. The model requires solution of a polynomial equation whose roots m ay be complex. Bounds to the real roots of the polynomial have also be en established. Two examples illustrating how the method is employed a re presented. The second example demonstrates that the iterative proce dure converges even in the complex domain, and that complex roots exis t for a real column.