The structure and the equations that represent a trayed distillation column are explored using bond graphs. Bond graphs model the power flow in a system, an inherently instructive way to view such a complex system. The power of bond graphs is evident by providing a clear, graphical representation of a distillation column that systematically organizes the equations and possible approximations.
The model of a distillation column is explored in general and then using a specific model used by Steven Gallun. Results reveal several ways of eliminating the algebraic loops and producing a dynamic model. The bond graph model can be expanded by introducing other elements including chemical reactions and thermal interaction with other columns.