In this work, we develop two generic mixed-integer linear programming
formulations for scheduling of multipurpose batch plants using the
unit-specific event-based modelling approach. While related
non-recycling production and consumption tasks are allowed to take place
at the same event points but in different real time in the first model,
they are not allowed in the second model. We also introduce the concept
of indirect and direct material transfer, which allows to conditionally
align the operational sequence of related production and consumption
tasks. Processing units are able to hold materials previously produced
over multiple event points. The computational results demonstrate that
the proposed models do not require a task to span over multiple event
points to generate the optimal solution. As a result, the proposed
models are able to generate the same or better solutions with up to one
order of magnitude less computational time compared to the existing
models.