Enterprise-wide Optimization for the Process Industry

Enterprise-wide optimization (EWO) aims to integrate and coordinate a company's entire value chain—including R&D, procurement, manufacturing, and distribution—to minimize costs, reduce inventories, and maximize overall profitability. For the process industry in particular, this means that EWO approaches need to combine accurate representations of the chemical manufacturing processes with models of the relevant business processes and market mechanisms.

Planning and scheduling constitute two important levels of decision-making in EWO. At the planning level, we are concerned with long-term strategic and tactical decisions including capital investments for capacity expansion, product portfolio management, purchasing or supply contracts, and long-term inventory positioning. Scheduling, on the other hand, considers short-term operational decisions including the sequencing of production processes, assignment of resources to tasks, and detailed production amounts. Process planning and scheduling are becoming increasingly complex as we consider additional operational aspects, e.g. maintenance and order promising (both of which are subject to strong uncertainty). Moreover, the integration of long- and short-term decisions remains a major challenge, especially in the context of renewables-based processes that need to deal with fluctuating availability of renewable resources, such as solar and wind, that exhibit seasonal and diurnal patterns. In our work, we develop optimization models (mostly mixed-integer programs) and algorithms to help make these decisions efficiently and reliably.

Supply chains enable the distribution of products and ultimately value creation. Supply chains in the process industries are highly complex as they typically involve multiple interdependent products, cover large geographical distances, and use various means of transportation. In addition, logistics decisions are often highly constrained by the production processes such that plant operations also have to be taken into account when designing or operating such supply chains.

The process industries have been experiencing major transformations in recent years, including the trend from product- toward service-oriented businesses, the increase in higher-value specialty products with more dynamic markets, shorter product life cycles, and the need to create a sustainable circular economy. For companies, adapting to these changes while remaining competitive requires effective supply chain optimization. In our work, we focus on the following aspects of supply chain engineering: integrated production and distribution, supply chain flexibility and reliability, and strategic network design and expansion planning.

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