An Extended Formulation for the Flexible Short-Term Scheduling of Multiproduct Semicontinuous Plants

Chemical plants are moving toward more-flexible environments, to adapt faster to market changes. For the sake of this flexibility, batch and continuous units might be integrated and operated along the same processing route in a semicontinuous mode, featured by production campaigns of finite duration. Constant production rates for the entire operation have been usually considered. Thus, production adjustments were achieved through storage resources, production line stops, and multiple product campaigns. The objective of this work is to improve the production schedules by developing a new concept for flexible manufacturing, which allows one to program production rate profiles within each semicontinuous operation campaign. Hence, the extended formulation presented allows to address the tradeoff between the opportunities that may arise when adjusting processing rates and the storage needs and opportunities. Finally, several case studies show that the proposed adjustment of the processing rates leads to less storage utilization and more-efficient production performance.