Computational precedence ordering in modular cascade systems

Situations where a non-redundant tear with respect to stream loops is impossible are frequently encountered in process simulation and give rise to difficulties in convergence of stream variables and overall heat and mass balances. Previous work has been directed at tearing the network at certain points rendering it acyclic and then precedence ordering the process units for computation. Such an approach is based on the structure of the directed graph alone and does not take into account in good measure the energy and mass flow patterns while precedence ordering. The idea in the present work has been to emphasise the stream loop as a major information recycle stream. Methods and criteria for precedence ordering simple and cyclic cascades have been established and shown to be better than the conventional cut set approach.