Analysis of commonly used scheduling models for multistage biopharmaceutical processes

Abstract

AbstractSeveral works have been reported in the literature over the past two decades to schedule a multiproduct facility in the biopharmaceutical industry. The present work attempts to analyze a few commonly used scheduling models, based on different time representations, for midterm planning or long‐term scheduling of multistage, multiproduct biopharmaceutical facilities for multiperiod demand. Several model inconsistencies/limitations in the published literature and in the reported Gantt charts, such as (i) real‐time storage violation, (ii) early product delivery, (iii) inadequate mapping of upstream and downstream tasks, (iv) no initial setup time, and (v) incomplete sequencing/modelling of storage tasks, thus (iv) overestimating the reported objective values in their results, are identified. Accordingly, one of the unit‐specific‐event‐based literature models is improved in this work to address these limitations. An improved model is proposed with enhanced/new features such as modified material balances, proper sequencing of storage based on storage bypassing allowed for intermediates and bypassing not allowed for products, modified shelf‐life constraints, initial setup time constraints, and updated bounds on storage, giving better results compared to the published literature models.