A mixed integer nonlinear programming formulation for optimal design of a catalytic distillation column based on a generic nonequilibrium model

The objective of this contribution is to propose a mixed integer nonlinear programming (MINLP) formulation for optimal design of a catalytic distillation column based on a generic nonequilibrium (NEQ) model. The use of this NEQ model presents two main advantages: (i) the computation of tray efficiencies is entirely avoided and (ii) the geometrical parameters of the column's hardware can be optimized. The minimization of the total annualized cost is submitted to three sets of constraints: the model equations, the product specification, and the tray hydraulic equations. The solution strategy for the optimization uses a combination of simulated annealing and sequential quadratic programming. Catalytic distillation of ethyl tert-butyl ether (ETBE) is considered as an illustrative example. The results of the optimization are discussed. Pre- and postoptimal sensitivity analysis is also performed.