An effective formulation for short-term scheduling of multipurpose batch plants

This paper presents a mixed-integer linear programming (MILP) mathematic model for short-term scheduling of multipurpose batch plants based on the representation of State Task Network (STN) for processes. When the model is built, the assignment of tasks and units is handled through one set of binary variables and the continuous-time representation is used. The model involves less binary variables, continuous variables and constraints than any other existing model. In order to improve the computational efficiency further, some effective techniques are developed to cut down the size of the proposed model based on the characteristics of batch plants and the model. Examples reveal the effectiveness of the model and improvement techniques.