Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


A dynamic pressure model of multicomponent distillation is developed in the frequency domain. The model consists of a set of linearized overall and component balances, enthalpy balance, pressure relationship, hydraulic equation and equilibrium relationships for each tray, the condenser and the reboiler of a general column. A numerical method consisting of total scaled pivoting Gaussian elimination with the method of residues is worked out for solving the model in the frequency domain to obtain all of the desired transfer functions. The resulting transfer functions are presented as Bode plots. The measure of interaction between the various control loops can then be calculated as a function of frequency based on the transfer functions between the chosen manipulated and controlled variables. As a result, this analysis can be useful in defining the control problem and predicting interaction difficulties. The computer program developed in this research can be used to study the effect of different model simplifying assumptions. The models being studied are pressure model, enthalpy model and equimolar overflow model. Also, a generalized steady state program and a mechanical design program were developed to make the frequency domain distillation column more realistic and generally appliable to a variety of columns at a variety of operating conditions.