Modelling simulation and optimisation of multi-component batch distillation.

In this thesis rigorous models for simulating the operation of multi-component batch distillation with a hypothetical start-up procedure are derived and solved by a novel analytical derivative technique. The conventional backward derivative technique which usually solves the model only from the steady-state total reflux condition is also extended to include the solution from the hypothetical start-up condition. Both techniques are shown to give identical results. Simulation and optimisation of a ternary system with slop recycle are analysed by using one of the above rigorous models and solution techniques. Nine modes of operation for handling the recycle slops are developed and a basic mode of operation for evaluating the economic efficiency is defined as the reference. The objective function chosen for the analysis is the profit per cycle time rather than the total product per cycle time. The results of analysis show that the right choice of mode of operation is more significant than the right choice of the constant reflux ratio of the operation. An explicit short-cut model for estimating the instantaneous overhead composition of multi-component batch distillation is successfully derived. The performance of the short-cut model is acceptably accurate and offers some advantages of speed over other published models. The short-cut model is shown to be very powerful for solving the problem of optimal reflux profile