A continuous time MILP model for short term scheduling of batch plants with pre-ordering constraints

This is a paper on an alternate model when pre-ordering constraints are imposed in short term scheduling of batch plants described by Pinto and Grossmann (1995). The idea is to include the assumption of pre-ordering of orders to units in the underlying representation for the model, as opposed to including pre-ordering as a separate set of constraints. The resulting model is not only conceptually simple, but also results in shorter solution times.