Polyethylene (PE) and polypropylene (PP)
In co-operation with our customers, we have implemented nonlinear model predictive control on several polyolefin plants with great success. These include multiple reactor systems producing bimodal polymers. The benefits of implementing MPC on polyolefin plants are stabilizing the solids concentration and production rate, leading to a production rate increase of 3-10% and increased catalyst productivity. Furthermore, benefits include faster and smoother grade transitions, leading to safer operation, less off-spec material, and more consistent product quality.
We have developed first principle state space models of several reactor types, such as slurry loop PE and PP reactors, fluidised bed gas phase reactors, liquid pool tank reactors, horizontally stirred bed reactor and autoclave LDPE reactor. We have worked on several catalyst systems, such as Ziegler-Natta, chromium, metalocene and initiators for free radical polymerization. The models describe dynamic component balances including the energy conservation, reaction kinetics, and calculation of measurements. Part of the models are also dynamic state variables describing product quality parameters such as MFR (MI), polymer density, production split, co-monomer content, and intrinsic viscosity.
