Influence of market fluctuations on the computational design of a chemical plant

This thesis is divided into five chapters. Chapter 1 introduces Luyben’s Conceptual design approach (based on Economic Potential levels, on CAPEXs and OPEXs) and its possible improvements. This method for economic plant evaluation will be adopted to study a styrene plant, which will be described in detail with regard to chemical substances, kinetics, and pieces of equipment involved. Chapter 2 explains the four degrees of freedom of the plant. With respect to Luyben (2011), also a splitting factor of the “LP Steam” flowrate will be considered. For each degree of freedom the dependence of different plant’s design variables will be found. After this prelim- inary part, economic study on the plant will follow a Conceptual Design evaluation, based on the choice of the optimal configurations. Chapter 3 is focused on the choice of the best algorithm to optimize the styrene plant. Different options will be compared, in particular customized grid methods and optimizers already included in MATLAB®. Another decisive matter is the choice of the best way of col- lecting data: the decision awards the link between UniSim® Design Suite and MATLAB®, in order to have easily controllable data, rather than using these two softwares separately. Chapter 4 passes from traditional Conceptual Design (CD) to Dynamic Conceptual Design (DCD) and to Predictive Conceptual Design (PCD). The differences among them will be underlined and econometric models on plant raw materials and commodities will be im- plemented. PCD will lead to the modeling and calculation of different scenarios for the possible future prices. The optimization of the different degrees of freedom will be studied for DCD and PCD. The final chapter, Chapter 5, summarizes the conclusions drawn from Conceptual Design, Dynamic Conceptual Design and Predictive Conceptual Design on the styrene plant. In addition to this, some further improvements to the plant and to the thesis work will be suggested.