Integrated Product-Process Design Approach for Polyethylene Production

Because polymer is a mixture composed of many repeat units, the properties of polymer with same repeat unit vary in different molecular weight distribution (MWD). MWD, in a sense, could be regarded as the formulation of polymer, producing tailored polyethylene (PE) with specified quality targets contains not only process design, but also formulated product design. Product design and process design problems were always solved separately in previous work, which led to a suboptimal solution. In this work, an integrated method for ethylene polymerization in solution with Ziegler-Natta catalyst is proposed to obtain optimal feed conditions and volume of reactor when polymer properties such as glass transition temperature and melt index are specified. In the proposed framework, MWD is found to be the key variable in the interplay between product design and process design. This optimization model is solved through nonlinear programming by maximizing profit which considers product revenue, material and reactor cost, and an illustrative example is presented to demonstrate the validity and advantages of the proposed approach.