Improving the tactical and operational decision making procedures in chemical supply chains

Nowadays, market trends have made companies modify the way of doing business. The current context of globalization, economic crisis, political conditions and competence among enterprises involves the continuous challenge for achieving their Key Performance Indicators. The successful achievement of these indicators depends on the Supply Chain (SC) efficiency. Thus, companies work towards the optimization of their overall SC in response to the competition from other companies as well as to take advantage of the flexibility in the restriction on world trade. This is done by the exploration of any resource flow (including raw materials and intermediates and final products, or energy), as well as any echelon of the Supply Chain network (such as suppliers, production plants, distribution centres and final markets). In this point, the Supply Chain Management addresses the process of planning, implementing and controlling the SC operations in an efficient way, throughout the management of material, information and financial flows across a network of entities within a SC. This includes the coordination and collaboration of processes and activities involved in this network. However, the complexity of considering the overall SC as well as the presence of uncertainty (demand, prices, process parameters) introduce more complexity in the coordination of all the activities or processes which take place through the SC. The aim of this thesis is to enhance the decision making process of industrial processes, by the development of new mathematical models to better coordinate all available information and to improve the synchronization production and demand, considering different time scales. Hence, this thesis presents a general overview of production process requirements within a SC and a review of the current state of the art, which has allowed to identify the open issues in the area in the context of Process Systems Engineering. Moreover, the first part of the thesis also presents an analysis of existing approaches, methods and tools used through this thesis. The second part of this work deals with the integrated management of production and demand constraints. This part first explores how the profitability of the SC can be improved by considering simultaneously production side and demand side management under deterministic conditions. Thus, discrete and hybrid time formulations have been presented to study the performance of the time representation. Furthermore, the discrete time formulation has been extended to deal with the external and internal uncertainty, through the implementation of a reactive approach. This part is also addresses the coordinated management of production and demand as well as the use of external and internal resources. Therefore, a new generalized mathematical formulation which integrates all resources involved in the production process within a supply chain is presented. The third part of this thesis is focused on the integrated SC optimization. Particularly, this part concerns the integration of hierarchical decision levels, by the exploitation of mathematical models that assess the consequences of considering simultaneously scheduling and planning decisions when designing a SC network. The Synthesis State Task Network concept is introduced to extend its typical representation of a process to incorporate information associated to the synthesis problem by the implementation of synthesis blocks. Finally, an integrated information management system based on an ontological framework is presented. The aim of this information platform is to coordinate all available information for decision making. This integrated platform will allow monitoring the real-time evolution of industrial processes within a supply chain. Moreover, this system may be used as an Operator Training System. Finally, the last part of this thesis provides the final conclusions and further work to be developed.